Survival, reasons for failure and clinical characteristics of anterior/posterior composites: 8-year findings

Abstract This retrospective study aimed to compare the annual failure rate (AFR), reasons for failure and factors influencing survival of posterior and anterior composite restorations placed by undergraduate students. Composite restorations placed by undergraduate students were evaluated. The restorations should be in occlusion, with at least one adjacent tooth; and patients should have been present for check-up, with at least 1 annual recall. The investigation was performed in two separate analysis: 1) dental electronic records of 100 patients (n=333 restorations) were selected to assess factors influencing survival; 2) clinical evaluation of 30 patients by examining restorations (n=123) to assess clinical characteristics and failure type distribution. Data were subjected to Kaplan-Meier method, Log-rank test, Cox regression and Fisher's Exact test (p<0.05). After 8-year period, the AFR was 2.62%. There was difference between anterior and posterior restorations (p=0.005), with anterior showing a higher AFR. The patient caries-risk (p<0.001) and the number of surfaces restored (p=0.010) affected restoration survival. The superficial brightness (p=0.029), fracture (p=0.025) and retention (p=0.011) were clinical criteria with differences between anterior and posterior restorations. Income (p<0.001), caries activity (p<0.001), caries risk (p<0.001) and oclusal risk (p<0.001) also influenced on the restorations survival. After 8-year, the AFR of restorations placed by undergraduate students was acceptable and affected by patient risk factors and the position of the tooth in the arch: anterior restorations failed more than posterior.

Resumo Este estudo retrospectivo comparou a taxa de falha anual (TFA), razões para falha e fatores influenciadores da sobrevida de restaurações posteriores e anteriores de resina composta realizadas por estudantes de graduação. As restaurações deveriam estar em oclusão, com pelo menos um dente adjacente, e os pacientes deveriam ter comparecido a pelo menos 1 consulta anual de retorno. A investigação foi realizada em 2 analises separadas: 1) dados odontológicos de prontuário eletrônico de pacientes (n=333 restaurações) foram selecionados para avaliar os fatores influenciadores na sobrevida; 2) avaliação de 30 pacientes por exame clinico das restaurações (n=123) para verificar as características clinicas e a distribuição do tipo de falha. Os dados foram submetidos a Kaplan-Meier método, Log-rank teste, regressão de Cox e Teste Exato de Fisher (p<0,05). Após o período de 8 anos, a TFA foi 2,62%. Houve diferença entre restaurações anteriores e posteriores (p=0,005), sendo que anteriores mostraram maior TFA. Os fatores de risco à carie (p<0,001) e o número de superfícies restauradas (p=0,010) influenciaram a sobrevida de restaurações. Brilho superficial (p=0,029), fratura (p=0,025) e retenção (p=0,011) foram critérios clínicos com diferenças entre restaurações anteriores e posteriores. Renda (p<0,001), atividade de cárie (p<0,001), risco à cárie (p<0,001) e risco oclusal (p<0,001) também influenciaram a sobrevida. Após 8 anos, a TFA das restaurações realizadas por estudantes de graduação foram clinicamente aceitáveis e afetadas pelos fatores de risco associados ao pacientes e a posição do dente na arcada; restaurações anteriores falham mais do que posteriores.

Surface roughness of orthodontic band cements with different compositions

OBJECTIVES: The present study evaluated comparatively the surface roughness of four orthodontic band cements after storage in various solutions. MATERIAL AND METHODS: Eight standardized cylinders were made from 4 materials: zinc phosphate cement (ZP), compomer (C), resin-modified glass ionomer cement (RMGIC) and resin cement (RC). Specimens were stored for 24 h in deionized water and immersed in saline (pH 7.0) or 0.1 M lactic acid solution (pH 4.0) for 15 days. Surface roughness readings were taken with a profilometer (Surfcorder SE1200) before and after the storage period. Data were analyzed by two-way ANOVA and Tukey's test (comparison among cements and storage solutions) or paired t-test (comparison before and after the storage period) at 5 percent significance level. RESULTS: The values for average surface roughness were statistically different (p<0.001) among cements at both baseline and after storage. The roughness values of cements in a decreasing order were ZP>RMGIC>C>R (p<0.001). After 15 days, immersion in lactic acid solution resulted in the highest surface roughness for all cements (p<0.05), except for the RC group (p>0.05). Compared to the current threshold (0.2 µm) related to biofilm accumulation, both RC and C remained below the threshold, even after acidic challenge by immersion in lactic acid solution. CONCLUSIONS: Storage time and immersion in lactic acid solution increased the surface roughness of the majority of the tested cements. RC presented the smoothest surface and it was not influenced by storage conditions.