UNIVERSIDADE FEDERAL DE PELOTAS Faculdade de Odontologia
Programa de Pós-Graduação em Odontologia
Dissertação
Restauração de lesões cervicais não cariosas: fatores relacionados a sua sobrevivência e impactos periodontais
Morgana Favetti
Morgana Favetti
Restauração de lesões cervicais não cariosas: fatores relacionados a sua sobrevivência e impactos periodontais
Dissertação, apresentada ao Programa de Pós-Graduação em Odontologia da Faculdade de Odontologia da Universidade Federal de Pelotas, como requisito parcial à obtenção do título de Mestre em Odontologia, área de concentração em Dentística.
Orientador: Prof. Dr. Maximiliano Sérgio Cenci
Co-orientador: Prof. Dr. Thiago Marchi Martins
Co-orientadora: Profa. Dra. Anelise Fernandes Montagner
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relacionados a sua sobrevivência e impactos periodontais / Morgana Favetti ; Maximiliano Sergio Cenci, orientador ; Thiago Marchi Martins, Anelise Fernandes Montagner, coorientadores. — Pelotas, 2017.
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FavDissertação (Mestrado) — Programa de Pós-Graduação
em Dentística, Faculdade de Odontologia, Universidade Federal de Pelotas, 2017.
Fav1. Ensaio clinico controlado randomizado. 2. Lesões
cervicais não cariosas. 3. Restauração dental permanente. 4. Recessão gengival. 5. Sistema adesivo. I. Cenci,
Maximiliano Sergio, orient. II. Martins, Thiago Marchi, coorient. III. Montagner, Anelise Fernandes, coorient. IV. Título.
Morgana Favetti
Restauração de lesões cervicais não cariosas: fatores relacionados a sua sobrevivência e impactos periodontais
Dissertação aprovada, como requisito parcial, para obtenção do grau de Mestre em Odontologia, Programa de Pós-Graduação em Odontologia, Faculdade de Odontologia de Pelotas, Universidade Federal de Pelotas.
Data da defesa: 21/02/2017
Banca examinadora:
Prof. Dr. Maximiliano Sérgio Cenci
Doutor em Odontologia, área de concentração em Cariologia pela Universidade Estadual de Campinas.
Prof. Dr. Mauro Elias Mesko
Doutor em Odontologia, área de concentração em Dentística Restauradora, pela Universidade Federal de Pelotas.
Prof. Dra. Patrícia Daniela Melchiors Angst
Doutora em Clínica Odontológica, área de concentração em Periodontia pela Universidade Federal do Rio Grande do Sul.
Prof. Dr. Fábio Herrmann Coelho de Souza (suplente)
Doutor em Odontologia, área de concentração em Dentística pela Universidade Federal de Pelotas.
Prof. Dra. Gabriela Romanini Basso (suplente)
Doutora em Odontologia, área de concentração em Materiais Odontológicos pela Universidade Federal de Pelotas.
Agradecimentos
À Universidade Federal de Pelotas e à Faculdade de Odontologia, por todo acolhimento e aprendizado desde a Graduação;
Ao Programa de Pós-Graduação em Odontologia, aos seus professores, e seu coordenador Prof. Dr. Rafael Ratto Moraes, exemplos de competência a serem seguidos;
Ao meu Orientador Prof. Dr. Maximiliano Sergio Cenci, pela oportunidade que por ele me foi concedida de fazer parte do PPGO-UFPel através de sua orientação atenta e competente, sempre incentivando meu crescimento acadêmico e pessoal.
Ao meu Co-Orientador Prof. Dr. Thiago Marchi Martins, um grande exemplo de docente e ser humano, pelos importantes conhecimentos transmitidos.
À minha Co-Orientadora Prof. Dra. Anelise Fernandes Montagner, pelo carinho e atenção, sempre disposta a ajudar e contribuir com o que fosse preciso.
Ao Prof. Dr. Alexandre Severo Masotti, que através de sua colaboração e disponibilidade no processo de avaliação dos pacientes, permitiu que este trabalho pudesse ser executado com maestria.
À Prof. Dra. Silvia Terra Fontes, que gentilmente compartilhou conosco os pacientes e sua tese de doutorado, para que pudéssemos dar continuidade à coleta de dados e acompanhamento destes pacientes.
Àos meus colegas e amigos de Graduação e agora, de Pós-Graduação Aryane, Andressa Spohr, Andressa Gastmann e Victório. Gratidão, por fazerem parte dessa jornada, pelo apoio e pela amizade. Foi um grande prazer compartilhar esse período da minha vida com vocês;
A todas os pacientes, participantes do estudo, pois sem eles este trabalho não estaria acontecendo;
Aos meus pais, Ivete e Reini, que serão sempre um exemplo de força, confiança, dedicação e amor. Por estarem sempre presentes e me fornecerem o suporte necessário. Se eu cheguei até aqui, foi porque vocês estavam sempre
à frente abrindo meus caminhos e apoiando minha trajetória rumo ao cumprimento de meus objetivos e sonhos;
Ao meu namorado e melhor amigo Lucas, obrigado pela compreensão, companheirismo e apoio. Teu carinho e tua companhia foram essenciais para tornar meus dias mais leves;
À todos que diretamente ou indiretamente participaram e contribuíram com minha formação, o meu sincero muito obrigada!
Notas Preliminares
A presente dissertação foi redigida segundo o Manual de Normas para Dissertações, Teses e Trabalhos Científicos da Universidade Federal de Pelotas de 2013, adotando o Nível de Descrição 3 – estrutura em Capítulos não convencionais, descrita no Apêndice do referido manual. <http://sisbi.ufpel.edu.br/?p=documentos&i=7> Acesso em: 21/11/2016.
O projeto de pesquisa contido nesta dissertação é apresentado em sua forma final após qualificação realizada em 3 de Setembro de 2015 e aprovado pela Banca Examinadora composta pelos Professores Doutores Fábio Garcia Lima, Natália Marcumini Pola e Mauro Elias Mesko (Suplente).
Resumo
FAVETTI, Morgana. Restauração de lesões cervicais não cariosas: fatores relacionados a sua sobrevivência e impactos periodontais. 2017. 112p. Dissertação Mestrado em Odontologia – Programa de Pós Graduação em Odontologia. Universidade Federal de Pelotas, Pelotas, 2017.
O presente estudo teve como objetivo avaliar os aspectos de sobrevida de restaurações diante das intervenções propostas por dois ensaios clínicos randomizados com tempos de acompanhamento diferentes, um com 36 meses e outro com 60 meses. Adicionalmente, objetivou-se avaliar a condição periodontal de pacientes que receberam restaurações em lesões cervicais não cariosas (LCNC) nestes estudos. O estudo com 36 meses de acompanhamento (Número de pacientes - Np = 42; Número de restaurações -Nr= 182), foi realizado com 3 diferentes grupos, nos quais aplicavam-se diferentes soluções (controle - solução placebo, experimental 1 - solução de clorexidina 2%, e experimetal 2 - solução de hipoclorito de sódio 10%) durante 60 segundos após o condicionamento ácido e antes da aplicação do adesivo e da restauração das LCNC. Sendo assim, este primeiro estudo deu origem à 2 estudos (estudo 1 e 2), respectivamente sobre os efeitos do pré-tratamento com CHX 2% e NaOCl 10% na retenção de restaurações em LCNCs. O estudo com 60 meses de acompanhamento (Np = 36; Nr = 172) deu origem ao estudo 3, sendo que este foi desenvolvido para avaliar o efeito de diferentes formas de isolamento do campo operatório (isolamento absoluto - com dique de borracha e grampo, ou isolamento relativo - com fio retrator, afastador labial, e ambos com sugador de saliva) para a realização de restaurações de LCNC. Um avaliador experiente, treinado e calibrado em cada um dos dois grandes estudos, avaliou as restaurações após 6, 12, 24, 36 ou 60 meses utilizando os critérios da FDI. Para a avaliação periodontal, um mesmo avaliador, padrão ouro, para ambos os estudos, avaliou os casos seguindo critérios pré-estabelecidos. Outro pesquisador comparou as informações obtidas com as já existentes nas fichas clínicas dos pacientes com as que foram obtidas no exame clínico e na aplicação do questionário realizados nos últimos recalls de cada estudo, de 3 ou 5 anos. A união dos dados periodontais oriundos das duas amostras, deu origem à um quarto estudo, que representa a associação entre os aspectos relacionados às restaurações (nível da margem e tipo de isolamento) e os tecidos periodontais adjacentes. Os resultados demostraram que a utilização de diferentes soluções, como clorexidina 2% ou hipoclorito de sódio 10%, durante o processo restaurador, bem como o tipo de isolamento realizado durante a execução do tratamento restaurador, não influenciaram a taxa de sobrevida das restaurações de LCNC ao longo do tempo. Ainda, do ponto de vista periodontal, o tipo de isolamento e a presença das restaurações não demonstraram gerar dano aos critérios periodontais avaliados após acompanhamento de 36 ou 60 meses. Houve relevante associação de determinadas características das lesões e dos pacientes com as taxas de falhas das restaurações.
Palavras-chave: Sistema adesivo, ensaio clínico controlado randomizado, restauração dentária permanente, lesões cervicais não cariosas, recessão genvival.
Abstract
FAVETTI, Morgana. Restoration of non-carious cervical lesions: factors related to their survival and periodontal impacts. 2017. 112p. Dissertation (Master degree in Dentistry). Graduate Program in Dentistry. Federal University of Pelotas, Pelotas, 2017.
The present study had as objective to evaluate the survival aspects of restorations before the interventions proposed by two randomized clinical trials with different times of follow-up, one with 36 months and another with 60 months. Additionally, the aim of this study was to evaluate the periodontal condition of patients who received non-carious cervical lesion restorations (NCCL) in these studies. The study with 36 months of follow-up (Number of patients - Np = 42; Number of restorations -Nr = 182) was performed with 3 different groups, in which different solutions were applied (control - placebo solution, experimental 1 - solution of Chlorhexidine 2%, and experimental 2 - 10% sodium hypochlorite solution) for 60 seconds after acid etching and before application of the adhesive and restoration of NCCL. Thus, this first study gave rise to two studies (study 1 and 2), respectively, on the effects of pretreatment with CHX 2% and NaOCl 10% on the retention of NCCL restorations. The study with 60 months of follow - up (Np = 36; Nr = 172) gave rise to study 3, which was designed to evaluate the effect of different forms of isolation of the operative field (absolute isolation - with rubber dam and clamp, Or relative insulation - with retractor wire, lip retractor, and both with saliva succion) for performing NCCL restorations. An experienced, trained and calibrated evaluator in each of the two large studies evaluated the restorations after 6, 12, 24, 36 or 60 months using the FDI criteria. For the periodontal evaluation, the same gold standard evaluator for both studies evaluated the cases according to pre-established criteria. Another researcher compared the information obtained with the already existing ones in the clinical records of the patients with those obtained in the clinical examination and in the application of the questionnaire carried out in the last recalls of each study, of 3 or 5 years. The union of the periodontal data from the two samples gave rise to a fourth study, which represents the association between aspects related to restorations (margin level and type of isolation) and adjacent periodontal tissues. The results demonstrated that the use of different solutions, such as 2% chlorhexidine or 10% sodium hypochlorite, during the restorative process, as well as the type of isolation performed during the restorative treatment, did not influence the survival rate of NCCL over time. Also, from the periodontal point of view, the type of insulation and the presence of the restorations did not show damage to the periodontal criteria evaluated after 36 or 60 months follow up. There was a relevant association between certain characteristics of the lesions and the patients with the failure rates of the restorations.
Key-words: adhesive system, randomized controlled trial, dental restoration permanent, noncarious cervical lesions, gingival recession.
LISTA DE ABREVIATURAS E SIGLAS
et al. e outros
FO Faculdade de Odontologia
IPV Índice de Placa Visível
ISG Índice de Sangramento Gengival
UFPel Universidade Federal de Pelotas
LCNC NG
Lesões Cervicais não cariosas Nível Gengival
mm Milímetro
PS Profundidade de Sondagem
CRX Clorexidina
NaOCl Hipoclorito de Sódio
Sumário
Resumo... 7
Abstract... 8
1 Introdução ... 11
2 Capítulo 1: Effectiveness of pre-treatment with chlorhexidine in restoration retention: a 36-month follow-up randomized clinical trial………. 15
3 Capítulo 2: Effect of sodium hypochlorite pre-treatment on the retention of restorations for non-carious cervical lesions: a 3-year randomized controlled trial……….… 30
4 Capítulo 3: Retention of non-carious cervical restorations placed under rubber dam or cotton rolls isolation: 60 months follow-up of a randomized controlled clinical trial ……….. 5 Capítulo 4: Effects of cervical restorations on the periodontal tissues………...………... 50 69 6 Considerações finais... 88 Referências ... 89 Apêndices ... 94 Anexos ... 110
1 Introdução
Restaurações de lesões cervicais não cariosas (LCNC) são tratamentos desafiadores, tanto pela longevidade, quanto pelo íntimo contato que possuem com os tecidos periodontais. A procura por este tipo de tratamento ocorre principalmente por questões estéticas e de sensibilidade dentinária. Esse mecanismo de dor, que impulsiona o paciente a procurar ajuda do cirurgião dentista, é melhor explicado pela teoria hidrodinâmica, sendo que tanto o início quanto a progressão da sensibidade dentinária são influenciados pelas características dos dentes, do periodonto, do ambiente oral e de influências externas (WEST et al., 2013).
O aparecimento de LCNC é tido como um evento multifatorial, onde diversas características do meio influenciam. A perda de esmalte e dentina pode ser devido a qualquer combinação dos processos de desgaste dos dentes, como abrasão, erosão ou abfração. A interação entre erosão e abrasão parece ser o maior responsável pelo desgaste na margem cervical e abertura de túbulos dentinários (PIKDÖKEN et al., 2011; TOMASIK, 2006).
Além da prevenção e controle dos fatores que estejam causando danos, existem opções de tratamentos que serão indicadas para cada caso de sensibilidade em LCNC. Há opções não invasivas, e relativamente rentáveis, que visam obstruir parcial ou completamente os túbulos dentinários abertos. Dentre as abordagens nāo invasivas, pode-se citar a aplicação de uma camada adesiva, dessensibilizadores ou verniz fluoretado, sendo que o paciente ainda pode fazer uso doméstico de dentifricios dessensibilizantes contendo nitrato de potássio, arginina ou nanoparticulas de hidroxiapatita (JENA; SHASHIREKHA, 2015; PETERSSON, 2013; SHARIF; IRAM; BRUNTON, 2013). Ainda, a aplicação de lasers também tem mostrado eficácia no combate à hipersensibilidade dentinária (SGOLASTRA et al., 2013).
Quando opta-se pelo tratamento restaurador, existem diferentes possibilidades de materiais a serem utilizados, como ionômero de vidro, ionômero de vidro modificado por resina e resina composta. No caso das resinas
compostas, estas requerem o uso de sistemas adesivos, os quais demonstram efetividade quando bem selecionados e aplicados (PEUMANS et al., 2014).
Porém, ao longo do tempo, falhas adesivas podem ocorrer, principalmente quando da adesão em dentina, a qual oferece um substrato mais delicado para o procedimento adesivo. A ação de metaloproteinases (MMPs) vem sendo reportada como um dos causadores destas falhas, já que após realizado o condicionamento ácido da dentina, estas enzimas presentes naturalmente na estrutura do complexo dentinho pulpar, podem ser ativadas devido à queda do pH. O sistema adesivo que deveria penetrar em toda a dentina descalcificada, nem sempre consegue atingir toda a superfície, e assim, algumas fibras de colágeno acabam ficando despotegidas e suscetíveis à açāo das MMPs (GÖSTEMEYER; SCHWENDICKE, 2016).
Na tentativa de reduzir estas falhas, pode-se indicar o uso de substâncias para aplicação durante o procedimento adesivo. A exemplo disso, nosso ensaio clinico controlado randomizado, utilizou substâncias com o intuito de inibir as MMPs, com a utilização de clorexidina 2%, e promover a remoção de fibras colágenas da dentina, com o uso de hipoclorito de sódio 10%, após aplicação de ácido fosfórico 37% e antes da aplicação do adesivo. Tais medidas tem o intuito de diminuir a degradação da camada adesiva ao longo do tempo, e assim, aumentar a longevidade adesiva das restaurações.
Porém, o sucesso das restaurações adesivas não dependem somente do material utilizado, dependem muito dos aspectos operacionais da técnica restauradora (DEMARCO et al., 2012). Fato este que vai desde o isolamento eficaz do campo operatório, até o cumprimento dos passos exigidos pelo fabricante do produto.
O tipo de isolamento do campo operatório (absoluto ou relativo) não é consenso entre os cirurgiões dentistas, devido à isto, comparar as diferentes técnicas é interessante. Isolamento dito absoluto com dique de borracha, grampo e sugador de saliva, ou isolamento relativo, com rodetes de algodão, fio retrator, afastador labial e igualmente, sugador de saliva, são técnicas disponíveis para se obter um ambiente seco e limpo, livre de contaminações por sangue ou saliva (ADA COUNCIL ON SCIENTIFIC AFFAIRS, 2003).
Mesmo quando as condições ideais para a execução da restauração são atingidas, há outro fator que exige cuidado, a gengiva que estará em intimo
contato com esta restauração, principalmente no caso de restaurações de LCNC. Deve-se procurar obter um acompanhamento efetivo do paciente, garantindo seu estado de saúde. É importante adequada instrução de higiene oral, para que o paciente consiga manter a saúde dos tecidos periodontais adjacentes à restauração, e que, através de uma escovação correta e atraumática, não cause aumento das lesões cervicais não cariosas antes existentes, nem originem novas recessões gengivais.
Duas grandes investigações foram conduzidas, e contemplam os estudos aqui apresentados. A primeira delas deu origem à 2 estudos (Capítulo 1 e 2), respectivamente sobre os efeitos do pré-tratamento com CHX 2% e NaOCl 10%, na retenção das restaurações de LCNCs, dados aqui reportados após 36 meses de acompanhamento, e a segunda (Capítulo 3), refere-se ao impacto do tipo de isolamento do campo operatório na taxa de falha das restaurações, também em LCNCs, após 60 meses. Ademais, após a união dos dados oriundos das 2 grandes amostras, um quarto estudo (Capítulo 4), apresenta aqui a associação entre os aspectos relacionados às restaurações (nível da margem e tipo de isolamento) e os tecidos periodontais adjacentes.
Os estudos tiveram acompanhamento de 6 meses, 12 meses, 24 meses, 36 meses e em um deles, de até 60 meses. No último acompanhamento feito em ambos, devido ao fato de se dar uma atenção especial aos critérios que envolvem a saúde periodontal adjacente às restaurações, aliou-se ao exame periodontal a aplicação de um breve questionário sobre hábitos possivelmente nocivos dos pacientes, como ranger ou apertar os dentes à noite ou durante o dia, se recebeu instruções de escovação e dieta quando fez as restaurações, se cumpriu com as recomendações caso tenha recebido, qual o tipo de escova e o tempo que ela costuma durar até a troca, qual o tipo de dentifrício utilizado, se é muito abrasivo ou não, e por fim se havia sensibilidade antes e após as restaurações terem sido feitas. Deste modo conseguimos obter uma ideia da possível etiologia destas lesões. No entanto, sabe-se que LCNC são de origem multifatorial (PEREZ et al., 2012), e devido à isso, devem ser tratadas com uma visão holística do paciente e seus hábitos, para que o tratamento possa ser realmente efetivo e não só paliativo.
A hipótese deste estudo, foi de que não haveria diferença significativa na utilização dos diferentes métodos restauradores ou de isolamento, tanto na
sobrevida das restaurações quanto na saúde gengival dos pacientes, após acompanhamento de 3 e 5 anos, respectivamente.
Sendo assim, o objetivo geral do presente estudo foi identificar a relação entre restaurações em LCNC e sua sobrevida, bem como os impactos periodontais em dois estudos clínicos randomizados com diferentes tempos de acompanhamento.
Dentre os objetivos específicos executados, estão:
- Avaliar a efetividade do pré-tratamento da superfície dentinária com solução de clorexidina 2% ou com hipoclorito de sódio 10%, na retenção das restaurações de LCNC, com até 36 meses de acompanhamento.
- Verificar os efeitos do tipo de isolamento dental durante o tratamento restaurador na sobrevivência de restaurações em LCNC, com até 60 meses de acompanhamento.
- Identificar a resposta periodontal dos tecidos adjacentes às restaurações de LCNC realizadas durante a execução de ambos os estudos acima, bem como, a manutenção ou as modificações das características periodontais ao longo do tempo.
Capítulo 1
Effectiveness of pre-treatment with chlorhexidine in restoration retention: a 36-month follow-up randomized clinical trial
Abstract
Objectives: This study aimed to evaluate the effect of the pre-treatment with 2% chlorhexidine as coadjutant in restoration retention of noncarious cervical lesions (NCCL) after 36 months of follow-up.
Methods: A randomized controlled split-mouth and triple-blind (operators, patients and evaluator) trial was carried out. Patients (n=42) with at least two non-carious cervical lesions were included. The teeth with NCCL were randomly assigned to two treatment groups: application of 2% CHX (experimental group) or a placebo solution (control group) for 60 s after acid etching and before the adhesive application. A trained and calibrated examiner evaluated the restorations at baseline (1 week) and at each recall (6, 12, 24 and 36 months) using the FDI criteria. A total of 225 restorations were evaluated after 36-month follow-up. Data were subjected to survival analysis using the Kaplan-Meier method, and the log-rank test was used to evaluate the existence of differences between the survival curves (α=0.05).
Results: The restorations survival rate after 36 months of follow-up was 76.1%.
There was no difference in the retention and failure rates between the experimental and the control group (p=0.968). There was an increased failure trend when restorations were located subgingival compared to those at the gingival level or supragingival.
Conclusion: The pre-treatment with 2% chlorhexidine digluconate did not promote further restoration retention of noncarious cervical lesions.
Clinical Significance: Determine of the application of 2% chlorhexidine as reducing MMP activity, improve the clinical performance of restorations over time as they have high index of failure.
Keywords: chlorhexidine, MMP inhibitor, adhesive system, randomized controlled trial, dental restoration, noncarious cervical lesions.
Introduction
The adhesion to dentin has been reported as a challenge to restorative dentistry [1], especially in high stressful situations such as the restoration of noncarious cervical lesions (NCCL), in which the retention of the restorative material relies only on its adhesion to the non-retentive cavity. Despite all advances, the micromechanical union between adhesive system and dentin substrate still presents limitations that could jeopardize the longevity of adhesive restorations in long term[2].
The loss of bond strength of resin to dentin occurs mainly by the degradation of the hybrid layer, and has been a problem which directly influences the longevity of the restoration. After etching, the adhesive system, should penetrate the entire decalcified dentin, as it does not always occur, collagen fibers are unprotected and susceptible to attack of metalloproteinases [3].
These enzymes are latently within the dentine and can be reactivated at the time of etching with phosphoric acid for the mineral dissolution. Still, they can be reactivated during the process of dental caries formation, or by the monomers present in the acid etch systems. It has been suggested that the suspension of the degrading activity of MMPs by protease inhibitors may modify the dentin surface after acid etching [4,5], and this could increase the long-term stability of resin-dentin interface.
The chlorhexidine digluconate (CRX) is an effective and non-specific MMP inhibitor evidenced both in vivo and in vitro studies [6,7]. Many in vitro studies have shown the chlorhexidine ability to prevent or at least retard the degradation of the collagen fibrils of hybrid layer, which could extend the durability of the adhesive bond between the tooth and restoration [8]. These results were recently summarized in systematic reviews [9,10]
There are only few clinical trials [11–13] evaluating the applicability of chlorhexidine in the longevity of restorations. Those studies showed no influence of the application for chlorhexidine prior to the dentin adhesion on the clinical durability of adhesive restorations. A recent systematic review concluded that
there is insufficient evidence to recommend or refute degradation inhibitory cavity pre-treatment prior adhesively placing resin-based restorations [14]. However, that conclusion was based mainly in studies presenting high risk of bias and with shorter follow-ups. Only one study presented low risk of bias [13]. These results may change if teeth are followed-up for longer.
Thus, the objective of this study was to evaluate the effect of the pre-treatment with 2% chlorhexidine as coadjuvant in restoration retention of noncarious cervical lesions, followed-up 36-month. The tested hypotheses were that the reduction of MMP activity by chlorhexidine provides better clinical performance of the restorations over time.
Materials and methods Ethical Aspects
This study was approved by the Local Ethics Committee (protocol 210/2011). It was registered in clinicaltrials.gov (NCT01947192), and followed the CONSORT guidelines [15]. Prior to the participation in the study, all participants signed a written informed consent.
Study Design
This study is a 36-month follow up of a prospective randomized clinical trial, designed as split-mouth and triple-blind (operators, patients and evaluator) [13]. The teeth with noncarious cervical lesions (NCCL) were randomly divided into 2 treatment groups: test group (application of CHX 2%) or control group (application of placebo solution), both applied after etching and before the adhesive system. Ten operators (undergraduate students from the last year of the School of Dentistry, Federal University of Pelotas) placed the restorations in 2011 and 2012 supervised by two researches (AFM and MSC).
Operators’ Training
The operators were previously trained according theoretical and practical aspects to ensure the standardization of clinical procedures and minimize variations inherent to different operators. During the theoretical phase, lectures were given and pre-clinical activities were conducted. During the practical phase, each operator performed the adhesive and restorative procedures in volunteers (10% sample) not included in this study.
Sample Size
Taking into account a 92.3% retention percentage after 36 months to NCCLs placed with the adhesive system Adper Single Bond 2 [16], the calculation of the size of the sample was based on a 20% difference in retention rates between
groups at a significance level of 5%, with a power of 80%, resulting in a sample of 35 patients in a split-mouth design. Considering the dropout rate throughout the trial period, the need for 40 patients was considered.
Patient’s recruitment
Subjects were recruited by the examination of patients under treatment at the School of Dentistry and by advertisements posters set in college. All those who needed dental treatment of NCCL and fulfilled the inclusion and exclusion criteria (Table 1) were invited to participate. Dental treatments were carried out in a dental clinic specially organized for the treatment of NCCL at the School of Dentistry, Federal University of Pelotas, to obtain the sample size required. All dental needs of the subjects enrolled in this study, except for prosthetic rehabilitation and orthodontic treatment, were provided.
NCCL screening
The selection of the NCCL was performed using a mouth mirror, an explorer and periodontal millimetre probe by two researches. Reasons for treatment were cervical tooth sensitivity, aesthetic complaints and/or prevention of further tooth damage. The depth of NCCL was measured by placing the probe in its deepest part, while the height was calculated by the distance between the most coronal to the most apical point of the cavity margins. The degrees of dentinal sclerosis were identified using a rating scale of 1 up to 4 [17]. The sensitivity test was measured by compressed air for 3s at a distance of 2-3 cm, while the adjacent teeth were protected with the fingers. Tooth vitality was tested using an Endo-frost cold spray on the tooth. No attempt was made to determine the aetiology of cervical lesions.
The teeth to be restored had a normal occlusal relationship with natural dentition and at least one adjacent tooth contact, were vital and had a positive response to cold. Cavosurface angleere not bevelled and no retentive grooves were placed. Study Groups
All volunteers who met the eligibility criteria were randomly divided into test or control groups, where the CHX 2% (test) or a placebo solution (control) were applied to the dentin after acid etching procedure.
Randomization and Blinding Procedures
Randomization was performed using a computer program (Microsoft Excel, 2010) by a person not directly involved in the study. A random table was used to allocate NCCLs in each study group by random numbers, for a person not directly involved in the clinical part of the study. The treatment was allocated regarding the tooth dental group (incisors, canines and premolars), where the first tooth
restored was raffled for treatment, while the next tooth from the same tooth-group was automatically assigned to the other treatment, according to the split-mouth design. Thus, after being randomly assigned, each patient received the same number of restorations of both groups, following the split-mouth design. Each operator performed the same number of restorations for both groups.
Individual opaque sealed envelopes were used to conceal the randomization sequence, which was coded as Treatment A or Treatment B. This condition enabled blinding of operators and patients because the clinical procedure was the same for both groups.
Clinical Procedures
The clinical protocol (the same for test and control groups) was printed and posted in each dental unit so the operator was able to easily review the. There was no making bevel or any cavity preparation before restorative procedures. Prophylaxis was done and the tooth shade was selected using a shade guide (VitaPan Classic, Vita Zahnfabrik, Bad Sackingen, Germany) before bonding procedures. Where necessary, local anesthesia was taken. All procedures were carried out using relative isolation method with labial retractors, cotton rolls, saliva aspirator and gingival retraction cord (Cord # 000 Ultrapak, Ultradent, South Jordan, UT, USA) into the gingival sulcus. The etching was performed with the 35% phosphoric acid (Adper Scotchbond Etchant, 3M ESPE) for 20 s in enamel and 15 s in dentin, followed by rinsing with air/water spray for 30 s and removal of excess moisture from cavity using absorbent paper. Afterwards, (1) for the test group CHX 2% was applied (manipulated solution; Intended Use Pharmacy, Pelotas, Brazil) under scrubbing action for 60 s using a disposable applicator and the solution excess was removed. For the control group (2), a placebo solution (solution similar to that used for test group, but without CHX) was applied on the cavity at the same way as for test group. The application of a two-step etch-and-rinse adhesive system (Single Bond 2 3M ESPE, St. Paul, MN, USA) was performed according the manufacture’s instructions and light-cured for 10 s using LED light-curing unit (Radii-Call; SDI, Bayswater, VI, Australia), intensity of 800 mW/cm2. The NCCLs were restored with a direct restorative nanocomposite resin
(Filtek Z350, 3M ESPE, Irvine, CA, USA) applied in at least two increments (no more than 2 mm thick), using a selected instrument (Hu-Friedy , Chicago, IL, USA). Each increment was light cured for 20 s.
Final contouring and polishing of the restorations were performed using a fine diamond burs and ultra-thin (KG Sorensen, Barueri, SP, Brazil) under refrigeration and low speed, floppy disks (Sof-Lex Pop-On, 3M ESPE), polishing paste (Diamond Excel, Dental Products FGM, Joinville, Brazil) and rubber tips (Enhance; Dentsply Caulk, Milford, dE, USA).
Clinical Assessment
Criteria approved by the FDI World Dental Federation were used for clinical evaluation of restorations [18]. The primary clinical outcome was the retention of the restoration, considering as failure, complete loss of restoration. Secondary outcomes included the criteria as follows: 1) marginal adaptation, 2) marginal staining, 3) the color of the surface, 4) post-operative sensitivity, 5) surface brightness, 6) translucency and color, 7) fracture, 8) anatomical shape and 9) preserving the vitality and integrity of teeth. Each criterion was expressed in five scores, three for acceptable and two for non-acceptable (repair or replacement). The evaluations were conducted by an experienced examiner previously trained and calibrated examiner. The examiner was blind to the intervention and was not involved in allocations or in restorative procedures. A Web-based tool (www.ecalib.info) and clinical setting evaluation were used for training and calibration of the examiner. The clinical intra-examiner calibration was carried out with 30 NCCL restorations, which were re-examined 15 days later. A pre-evaluation intra-agreement of at least 90% was obtained.
Recalls
Telephone contact was made with the patients to recall them for the periodic assessment of the restorations. Those who were not touched by phone call; letter was sent to the home address identified in the records. At each recall, the examiner evaluated the restorations blindly. Revaluations were made for periods of 6 months, 12 months, and 24 months after 36 months. Considering that some patients took more time to attend to the recalls the time of follow up extended for more than 36 months for some cases.
Statistical Analysis
Data were subjected to survival analysis using the Kaplan-Meier method. The log-rank test was used to evaluate the existence of differences between the survival curves. Crude Cox regression models with shared frailty were used to verify the association between treatment and the risk of failure over time, estimating the Hazard Ratios (HR) and 95% confidence intervals. Statistical analysis was carried in October using Stata 11.0 Statistic Program (Stata Corp LP, College Station, TX, USA).
Results
During the enrolment, from September 2011 to August 2012, 61 subjects were assessed for eligibility. Forty-two patients (20 men and 22 women, mean age 49.7 years old) were enrolled in the study. After 36-month follow up, 29 patients returned for re-evaluations. Details of the recruitment procedures, exclusion
characteristics of the patients, and the number of participants through each stage of the trial are disclosed in the flow diagram (Figure 1).
A total of 105 restorations were evaluated at 36-month follow up. The restorations survival rate after 36 months of follow-up was 76.1%. The annual failure rate of restorations was 8.4% at 3 years of follow up, and 5.5% at 2 years follow-up. Figure 2 shows the Kaplan-Meier survival curves for both groups. It is possible to observe that there is no difference between experimental and control groups (p=0.968). The same result was found in cox regression model with shared frailty (Table 2). As is seen in Table 2, there is a tendency to failure increased when restorations are located subgingival compared those to the level and supragingival. On the data obtained, it can be inferred that the use of chlorhexidine has not affected the risk for failure of restorations during the follow-up.
Discussion
The findings of this study showed that there was no difference in the retention and failure rates between the experimental and the control groups, up to 36 months follow-up. Although the chlorhexidine group presented a higher trend for failure risk in restorations survival, there was no difference compared to the control group. The hypothesis that the reduction and / or inhibition of MMPs by chlorhexidine top clinical performance of restorations promotes' survival over time was not confirmed.
Previous clinical trials studies [12,13] also showed no difference in survival of non-carious cervical lesions using chlorhexidine as a coadjutant in the adhesive procedure. Thus, so far, the increasing of an extra step of adhesive procedure (the application of chlorhexidine solution) has not presented any advantage. At present, there is only a single other trial that reported more than 24-month follow up, and this study also concluded that etching with chlorhexidine digluconate does not increase the durability of noncarious cervical restorations in 36-month [11]. Maybe, even longer follow-ups are needed to show an evidence of the MMP inhibition by chlorhexidine.
The laboratorial evidence does not convincingly support those findings showed in clinical studies. Chlorhexidine has being used as a coadjuvant for dentin adhesion and had showing a satisfactory effect on decreasing the resin-dentin bond degradation long time [9], in in vitro and ex vivo studies, mainly in the first months of function in the oral cavity [19]. Preserving the long-term integrity of the resin-dentin hybrid layer in dental restoration by MMP inhibition is relevant, as it could increase the longevity of restorations. However, the available clinical data on effect of pre-treatment with chlorhexidine do not support such treatment for reducing risk of retention loss or restoration failure [3]. Moreover, further outcomes like safety (pulp irritation, allergy) should be assessed regarding
chlorhexidine application. So far, there is no indication that pre-treatment is harmful.
Concerns still last regarding the use of chlorhexidine, studies exploring the relationship between the concentration of chlorhexidine and bond strength values have been performed and showed that the association between these aspects does not occur linearly [10]. Chlorhexidine when applied to the dentin surface at concentration equal to 0.1%, or greater, can Improve the bond strength values long-term in vitro, by reducing the degradation mediated by endogenous enzymes [20]. In a recent systematic review of this association, it was shown that in most studies, pre-treatment with CHX presented smaller reduction in bond strength than the control groups [21].
Nevertheless, it is important to note a relevant limitation of the clinical trials as the patients accompaniments for long periods of time, since it can occurs the loss of these patients, and consequently the loss of their data. Specially regarding the subjects of this present study, the no return happens either by loss of contact with them. Many patients changed the phone numbers or change the address. This hinders the return and reduces the number of collected data.
In general, failure of restorations of NCCL might not have been solely related to MMP inhibition treatment. Other factors such as caries risk or cavity size/shape could influence restoration survival [22].The depth, height and cavity shape (configuration) definitely play a role for failure-prognostic variables, as deeper and wider lesions has presented more retention failure than the others [13]. However, the effect of cavity configuration or location in relation to the marginal gingiva were not significant factors in the present study. The treatment of NCCLs has a multifactorial character and presents clinical difficulties for restorative procedures. Other parameters not only associated with restorative factors must be observed, such as patient characteristics, diagnosis of harmful oral habits and etiological factor removal [23]. In order to improve survival rate of restorations, factors related to the patient and operator are of primary importance [24]. Therefore, treat the cause first can increase our restorations success rates. Different approaches should be made to each specific situation. Considering the effect of these patient individual characteristics on the survival of restorations, we have carried out the present study with a split-mouth design to reduce the impact of these variations on the research question.
Within the period of 36-month, noncarious cervical restorations placed with both treatments performed equally with a survival rate of 76.1%, with acceptable clinical performance. The application of CHX as a MMP inhibitor used as a pre-treatment in dentin adhesion did not influence the retention of NCCL restorations after 36-month of follow-up.
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Figures and Tables
Figure 1. Flowchart showing the enrolment of the study participants. Np: number of patients; Nr: number of restorations.
Figure 2. Kaplan-Meier survival curves of the control and experimental groups over the years (p = 0.968; Log Rank test).
Table 1 . Inclusion and exclusion Criteria used in this research
Inclusion criteria:
• Patients with at least 2 NCCLs in incisors, canines or pre molars; • Patients with more than 20 teeth present in the mouth;
• Patients above 18 years of age;
• Patients able to understand the free and informed consent (IC);
• NCCLs with at least 1mm deep on the buccal teeth and may extend with a small part for interproximal region;
• Individuals with good periodontal health. Exclusion criteria:
• Patients smokers; • Patients with bruxism;
• Patients with severe systemic diseases; • Patients undergoing orthodontic treatment; • Teeth with NCCL but without antagonists;
• Teeth wear facets with greater than 50% at the incisal and / or occlusal faces; • Presence of decay or restoration in the area to be treated;
• Visible plaque index (VPI) and gingival bleeding index (GBI) greater than 20%; • Probing depth and clinical attachment loss greater than 4 mm, with probing bleeding;
Table 2. Unadjusted (u) and Hazard Ratios (HR:95%CI) for failure of the restorations according to clinical variables. Cox Regression Analysis.
Variables HRu (95% CI) P-value
Treatment Control CHX 1.00 1.07 (0.58;1.96) 0.826 Shape of cavity U-Shaped V-Shaped 1.00 1.17 (0.56;2.44) 0.682 Dentin sclerosis Absent Present 1.00 1.57 (0.77;3.20) 0.217 Gingival Margin Supragingival At gingival margin Subgingival 1.00 1.98 (0.79;4.94) 2.42 (0.63;9.29) 0.295
Capítulo 2
Effect of sodium hypochlorite pre-treatment on the retention of restorations for non-carious cervical lesions: a 3-year randomized controlled trial
Abstract
Objective: This study aimed to evaluate the failure rates of composite restorations of non-carious cervical lesions (NCCL) performed with or without the pre-treatment with 10% sodium hypochlorite (NaOCl) on etched dentin.
Materials and methods: A randomized controlled split-mouth and double blind clinical trial was carried out. Patients (n=30) with at least two NCCL were included and 100 NCCL were restored. Each patient received at least one pair of composite restorations (Filtek Z350/3M ESPE), bonded either with 2 techniques: control (acid etching + placebo solution for 60 seconds + Adper Single Bond 2/3M ESPE) or experimental (acid etching + 10% NaOCl for 60 seconds + Adper Single Bond 2). A calibrated examiner evaluated the restorations (baseline, 6-, 12-, 24- and 36-month) using the FDI criteria. The primary outcome was retention of the restoration. The data were submitted to the chi-square for the frequency of failures according to the characteristics of the patients and the lesions. Survival data were analyzed with the Kaplan-Meier method, log-rank test and Cox regression (p<0.05).
Results: The average lifetime of the restorations in this study was 2.86 years. The annual failure rate was 9% for the control group and 17.8% for the experiential group. According to the Cox regression, the group that used NaClO failed 40% more than the control group, but there was no statistically significant difference compared to control (p = 0.075). A greater failure rate was observed in patients with the presence of fewer teeth in the mouth (p=0.320), in teeth at the lower arch (p=0.039), and mainly, in premolars (p=0.013).
Conclusion: The pre-treatment with 10% sodium hypochlorite as an adjuvant in dentin adhesion did not improve the retention rate of NCCL restorations .
Clinical Significance: The use of 10% hypochlorite to remove collagen fibers from the dentin does not have any benefit for the retention of NCCL restorations in a 36 months follow-up.
Keywords: randomized controlled trial, dental restoration, noncarious cervical lesions, sodium hypochlorite.
1. Introduction
An effective and stable composite-dentin adhesion is fundamental for the long-term durability of composite restorations, especially when little or no marginal enamel is available for bonding [1]. In challenging situations, as the restorative treatment of non-carious cervical lesions (NCCLs), the lost of restoration’s retention is a common reported problem [2]. Clinical studies of NCCLs restored with composite and without mechanical retentions constitute a worthy model for evaluating the clinical performance of adhesive restorations, since the retention of those restorations depends on the adhesive procedure [3]. Moreover, the prognosis of cervical restorations may be affected by several factors, not only the adhesive procedure is defying, but also the clinical characteristics of the cervical lesion and aspects related to the patient could play a role in the retention rate of restorations [2].
It is known that phosphorical conditionated dentin is still a challenge, since there are demineralized areas where the adhesive monomer does not have a good infiltration, which leaves exposed collagen not impregnated by adhesive [4,5]. These collagen fibrils can undergo hydrolysis, which directly interferes with the degradation of the adhesive interface long-term. Based on this aspect and taking into account the difficulties related to the presence of collagen in hybridization, the attempt to remove dentin collagen by means of sodium hypochlorite (NaOCl) application after phosphoric acid etching was considered. NaOCl, a nonspecific proteolytic agent, has the ability to dissolve collagen proportional to the time of application and to the concentration of active chlorine and superoxide radicals [6,7]. At 10% NaOCl concentration applied after dentin acid etching and before adhesive application, it promotes deproteinization of the dentin surface. Further, the application of sodium hypochlorite aims to promote the exposure and amplification of the dentin tubules, making the dentin reacts similar to the enamel, which is a favorable surface for adhesion [8,9].
Some in vitro studies have demonstrated that collagen removal techniques after dentin conditioning increase the dentin bond strength when compared to the conventional etching – without collagen removal [10,11]. However, another in
vitro studies have shown that pre-treatment with sodium hypochlorite for dentin
deproteinization did not demonstrate any superior adhesive efficiency when compared to the conventional adhesive technique long-term [8,12]. Because positive (and sometimes controversial) results have been reported in laboratory studies, the effectiveness of the collagen removal technique needs to be clinically further evaluated.
Clinical studies evaluating the performance of the deproteinization technique are scarce [13,14]. A previous pilot study concluded that the preliminary evaluation of the sodium hypochlorite treatment in the restoration of non-carious cervical lesions is encouraging [13]. Although no significant differences were noted between the conventional (acid etch only) and deproteinization (acid etch + collagen removal) techniques; additional, it was suggested that the type of adhesive system might negatively affect the collagen
removal technique [14]. A similar trend has also been noted in laboratory studies [8,15] although conflicting results have been reported.
By foregoing, there is still uncertainty as how this type of dentin pre-treatment could clinically collaborate with the survival of the restorations. Thus, the aim of this study was to evaluate the failure rates of composite restorations of NCCL performed with or without the pre-treatment with 10% NaOCl on etched dentin. The hypothesis of the present study was that the application of deproteinization solution after acid etching does not influence the failure rate of the restorations after a follow-up of 3 years.
2. Materials and methods 2.1. Ethical considerations
The present research was approved (protocol 210/2011) by the Ethics Committee (CEP) of the School of Dentistry of the Federal University of Pelotas (FO-UFPel). It was registered in clinicaltrials.gov and was reported according to the guidelines of the Consolidated Standards of Reporting of Trials (CONSORT) [16]. Prior to participating the study, all selected patients signed a free and informed consent form.
2.2. Study Design
This study was a 3-year follow-up of a randomized clinical trial. The control group used a placebo (water) solution, and the experimental group used 10% sodium hypochlorite, both applied after dentin acid etching with 37% phosphoric acid and before the adhesive system. It is a split-mouth and double blind (patients and evaluator) study. It was not possible to blind the operators because of the characteristic smell of sodium hypochlorite. The NCCL restorations were placed, between 2011 up to 2012, by 10 operators (undergraduate students from the last year of the Dental School) supervised by two researches (AFM and MSC).
2.3. Operators' Training
Theoretical and practical training of the operators was performed in order to minimize variations among operators. The undergraduate students received a manual containing materials’ instructions and the protocol of clinical procedures. In addition, there were pre-clinical demonstratives training. For training, the operators restored a number of teeth corresponding to 10% of the total NCCL sample size in patients, following the same instructions received for clinical execution, although those restorations/patients were not included on the sample of the study.
2.4. Sample Size
Taking into account a 87% retention percentage after 36 months to NCCLs placed with deproteinization technique [14] the calculation of the sample size was based on a 20% difference in retention rates between groups at a significance level of 5%, with a power of 80%,considering a sample loss during the follow up, the sample size resulted in 30 patients in a split-mouth design.
2.5. Recruitment and selection of patients
The disclosure of the study was done through posters and pamphlets, and patients who were interested in participating were clinically evaluated.
The inclusion criteria of the study were: a) patients with at least 2 NCCLs in incisors, canines or pre molars, b) patients with more than 20 teeth present in the mouth, c) patients above 18 years of age, d) patients able to understand the free and informed consent and e) individuals with good periodontal health.
The exclusion criteria were as follows: a) smokers, b) patients with bruxism, c) patients with severe systemic diseases, d) patients undergoing orthodontic treatment, e) teeth with NCCL but without antagonists, f) teeth with wear facets covering more than 50% at the incisal and / or occlusal surfaces, g) presence of decay or restoration in the area to be treated, h) visible plaque index (VPI) and gingival bleeding index (GBI) greater than 20%, probing depth and clinical attachment loss greater than 4 mm, with probing bleeding, i) lack of interest in return for follow-up or refusal to participate.
Patients who fulfilled the criteria received an informative letter about the purpose of the study, as well as a free and informed consent form to be signed, proving their voluntary interest in participate in the study. A detailed initial clinical examination, including several criteria regarding the classification of NCCLs, was met among the selected patients.The criteria for evaluation of NCCLs included the following parameters: cervical lesion shape ("U" or "V"), length and height of the lesion, relation of the cervical wall of the lesion with the gingival margin (supragingival, gingival or subgingival margin), presence of wear facets, presence and degree of dentin sclerosis when present, dentin sensitivity and pulp vitality.
2.6. Randomization Blinding Procedures
Randomization was performed using a computer program (Microsoft Excel, 2010), by a person (TPC) not directly involved in the study. A random table was used to allocate the NCCLs in each study group. The treatment (control and experimental) was allocated regarding the tooth-group (incisors, canines and premolars), where the first tooth restored was raffled to one treatment, while the next tooth from the same tooth-group was automatically assigned to the other treatment, according to the split-mouth design. Thus, after being randomly
assigned, each patient received the same number of restorations of both groups. Each operator performed the same number of restorations for both groups.
Individual opaque sealed envelopes were used to conceal the randomization sequence, which was coded as Treatment A or Treatment B. The same clinical sequence and identical bottles were used for both groups. However, due to the characteristic odor of sodium hypochlorite, the operators could identify the treatment solutions.
2.7. Clinical Protocol
Before the adhesive procedures, the prophylaxis of the tooth was performed with rubber cup and paste based on pumice and water. No cavity preparation or cavo-surface margin beveling was performed. Before the isolation of the teeth, the color of the restoration was selected, following a color scale (Vitapan Classical, Vita Zahnfabrik, Bad Sackingen, Germany). When necessary, local anesthesia was taken.
After those preliminary steps, relative isolation of the operative field was performed, using labial retractor, gingival retraction cord # 0000 (Ultrapak Cord, Ultradent, South Jordam, UT, USA), cotton rollers and saliva aspirator. After isolation, 37% phosphoric acid gel was applied to the surface for 15 sec, followed by washing with air / water spray for 30 sec and drying with absorbent paper. Then, for the experimental group, a manipulated solution of 10% sodium hypochlorite (Uso Indicado Pharmacy, Pelotas, RS, Brazil) was applied with a disposable pharmaceutical syringe, remaining 60 sec in contact with the dentin surface. Subsequently, a thorough washing with air / water spray was performed for 30 sec to remove as much residual NaOCl as possible. For the control group, the same sequence was followed, however, using a placebo solution (similar to the solution used for the experimental group but without NaOCl).
For both groups, the application of a two-step etch-and-rinse adhesive system (Adper Single Bond, 3M ESPE, St. Paul, MN, USA) and restorative technique using a nano-particulate composite resin (Filtek Z350, 3M ESPE, St. Paul, MN, USA) were performed as recommended by the manufacture’s instructions. Each increment was cured for 20 sec with a LED light-curing unit (Radii-Call; SDI, Bayswater, VI, Australia), intensity of 800 mW/cm2.
All restorations were finished with # 12 scalpel blade, fine and ultra-fine grained diamond burs (KG Sorensen, Barueri, SP, Brazil) under water-cooling in order to remove excess material and / or improve the contour shape of the restorations. Polishing was done with silicone tips, flexible discs of sandpaper (Sof-Lex Pop-On, 3M ESPE, St. Paul, MN, USA), felt disks and polishing paste.
2.8. Clinical Assessment
A previously trained, calibrated and blinded examiner (MSC) who worked as examiner in other clinical trials carried out the clinical evaluations at baseline (1 week) and follow-up periods (6-, 12-, 24- and 36-month). A web-based training and calibration tool (www.ecalib.info) and clinical setting evaluation were used for training and calibration of the examiner. The clinical intra-examiner calibration was carried out with 30 Class V restorations, which were re-examined 15 days later. A pre-evaluation intra-agreement of at least 90% was obtained.
The examiner used the criteria approved by the FDI World Dental Federation [18] for the clinical evaluation of the restorations. The primary clinical outcome was the retention of the restoration, considering failure the complete loss of restoration. Secondary endpoints included: marginal staining, the color of the surface, post-operative sensitivity, surface brightness, translucency and color, fracture, anatomical shape and preserving the vitality and integrity of teeth. Each criterion was expressed in five scores, three for acceptable and two for non-acceptable (repair or replacement).
2.9. Recalls
Patients were asked for re-evaluations in the 6-month, 12-month, 24-month, and 36-month periods. Contact was made by telephone call (provided by the patient during the last visit). In cases where there was no contact success, letters were sent to the residential address informed in the clinical record. Furthermore, in cases where the letters did not return, home visits were made by the researchers and evaluators involved in the recalls (MSC and MF). In these follow-ups, the restorations were evaluated according to FDI criteria and photographic records were recorded.
2.10. Statistical Analysis
Statistical analysis was carried using Software Stata 14.2 (Stata Corp LP, College Station, TX, USA). Descriptive analysis of interest variables was carried-out. Differences between frequencies were assessed by Exact Fisher test. Survival analysis was performed using Kaplan-Meier method. The log-rank test was used to evaluate the existence of differences between the survival curves. Unadjusted Cox regression models with shared frailty were used to verify the association between treatment and the risk of failure over time, estimating the Hazard Ratios (HR) and 95% confidence intervals. Annual failure rates were calculated as described by Opdam et al., 2010 [19]. All analyses considered an α=5%.
3. Results
During enrolment from September 2011 to August 2012, 62 patients were assessed for eligibility, of whom 32 did not fulfilled the inclusion criteria or did not want to participate. Thus, 30 patients (17 men and 13 women), mean age of 49-year old (71.9% of the sample was between 41-60 49-years), with 100 restorations in total, were enrolled in this study. Details of the recruitment procedures, exclusion characteristics of the patients, lost and the number of participants through each recall of the trial are disclosed in the flowchart (Figure 1).
The average lifetime of the restorations in this study was 2.86 years. At 36-month, the annual failure rate was 9% for the control group and 17.8% for the experimental group.
In Table 1 it is possible to observe some characteristics of the subjects evaluated at the last recall (36-month). Most patients had less than 24 teeth in the mouth and 63.3% of the patients reported the consumption of acid foods and / or sour drinks, causing erosion. In addition, the presence of lesions in patients with lower income and intermediate educational level was observed in our patients on a larger scale (Table 1).
In Table 2 it is possible to observe the characteristics of the non-carious cervical lesions. Regarding the characteristics of the restored lesions, it is possible to emphasize that the most prevalent were "V" shaped cervical lesions, with an average depth of less than 1mm and an average height of 1 to 3mm. The most restored type of teeth were premolars (Table 2).
The Kaplan-Meier survival curves are presented in Figure 2. When observed the failures and their distribution among the characteristics of the patients and of the NCC lesions, there was a significant difference when comparing the upper and lower jaw, with lower jaw showing more failures than maxillary (p = 0.039). There was also a significant difference in failure rates considering the tooth type, with premolars tooth-group presenting more failures (p = 0.013). However, the type of dentin treatment (control and experimental) did not influence on failure rates (p = 0.077) as well as the number of teeth in month (p = 0.320 ). The data found in the Cox regression confirm these results regarding their association significance (Table 5). Regarding the type of treatment, the group that used NaOCl solution failed 40% more compared to the control group, but the association was not significant (p = 0.075), this may be due to insufficient sample size. The other evaluated criteria followed the same trend of Kaplan-Meier survival curves.
When the data were submitted to the chi-square test (Table 3), in order to measure the quantity and the percentage of the data according to the presence or not of failure, it is observed that there was no significant difference in the failure rates between the experimental and the control group (P = 0.054). Table 3 presents the variables influence on restoration’s retention. None studied variable affected the restoration’s retention (all p > 0.05).
