Periodontal response to a tricalcium silicate material or resin composite placed in close contact to the supracrestal tissue attachment: a histomorphometric comparative study.

OBJECTIVE: Subgingival dental restorations and periodontal health have been studied for many years; however, there is a low histological evidence on the behavior of new materials in the supracrestal tissue attachment. The aim of this study is to analyze the periodontal response when a tricalcium silicate material (TSM) or composite margin restorations is placed to 0.5 mm and 1.5 mm from the bone crest with a histomorphometric analysis in dogs. METHODS: Nine mongrel dogs were used in this study: four dogs (8 canine teeth) for TSM group, 4 dogs (8 canine teeth) for composite group, and 1 dog (2 canine teeth) with cavities without restorations. Cavity preparation of 2×2×1 mm was created on the buccal aspect of the canines at 0.5 and 1.5 mm of the crestal bone. Cavities were restored with composite and TSM or were left unrestored as control. After 12 weeks of healing, the dogs were euthanized and blocks containing the tooth and soft tissues were processed. RESULTS: In all the specimens, the junction epithelium was stablished apical to the tooth preparations. A shorter distance to the bone (0.5 cavity) implies greater apical periodontal migration regardless of the material used. In the TSM groups, the connective tissue height and the distance between bone level and apical margin preparation were greater than those in the composite groups, while the epithelium height was less. However, there were no statistically significant differences comparing TSM and composite groups at either 0.5 mm or 1.5 mm (p > 0.05). CONCLUSION: Histologic analysis did not show periodontal reattachment to TSM or composite. In both cases, bone crest migrates apically. For that reason, it is recommended to perform composite restorations at the subgingival level whenever the distance to the bone crest is at least 2 mm. CLINICAL RELEVANCE: Both composite and TSM do not achieve reinsertion of the connective tissue in the biological width.

Long-term clinical evaluation of Dyract compomer in the restoration of non-caries cervical lesions: A 20-year retrospective study.

OBJECTIVE: The restoration of non-caries cervical lesions has long been a challenge. Until recently, compomers were the restorative materials of choice. The aim of this in-vivo study was to evaluate the long-term clinical performance of Dyract restorations in non-caries cervical lesions. METHOD AND MATERIALS: Forty-two patients with Dyract restorations of non-caries cervical lesions performed in 1995 by the same operator were included in this in-vivo retrospective study. After 20 years, restorations were evaluated by two calibrated examiners following the USPHS criteria modified by Ryge. RESULTS: After 20 years, 38 of the 54 restorations included in this study remain in service (70.4%). Debonding was the cause of all failures. Marginal adaptation and marginal discoloration were the categories with poor values. CONCLUSION: Dyract restorations can be considered a treatment option for non-caries cervical lesions, because they show good long-term clinical performance for 20 years. CLINICAL RELEVANCE: Dyract restorations continue to be an option to restore non-caries cervical lesions, due their good long-term clinical performance and the ease of the clinical procedure. The survival rate of these Dyract restorations was high after 20 years (70.4%). However, the limitations of marginal discoloration, marginal adaptation, and color match should be considered.

Retrospective evaluation of posterior composite resin sandwich restorations with Herculite XRV: 18-year findings.

OBJECTIVE: The aim of this retrospective study was to evaluate the long-term clinical outcomes of posterior composite resin sandwich restorations, and secondarily to assess the influence of potential factors on survival and causes of failure. METHOD AND MATERIALS: Two hundred and four posterior Herculite XRV restorations due to primary caries performed between 1991 and 1997 were included. The restorations were assessed after 18 years, by two calibrated examiners, according to USPHS criteria. The survival of the restorations was estimated by the Kaplan-Meier estimator. Cox regression was applied to evaluate the influence of the cavity size, location of the tooth, caries risk, and gender on survival rate. The predictive power of the analyzed variables on survival rate was studied with multiple linear regression analysis. RESULTS: After 10 years the survival rate was 92.6%, and 82.4% at the end of the study. Thirty-six (17.6%) restorations failed during the evaluation period, 21 (10.3%) of them after more than 10 years. The most common failure was secondary caries (69.4% of the failures). There were statistically significant differences in survival rate depending on caries risk (P = .000), but not between Class I and II (P = .106), and the type and localization of the tooth (P = .115). CONCLUSION: Posterior Herculite XRV restorations due to primary caries have high long-term survival rates. Generally, failures occur by secondary caries and are more common in molars. The patient's caries risk is the variable that best predicts the survival of posterior restorations.

Mechanical properties related to the microstructure of seven different fiber reinforced composite posts.

PURPOSE: The aim of this in vitro study was to evaluate the mechanical properties (bending strength and hardness) of seven different fiber reinforced composite posts, in relation to their microstructural characteristics. MATERIALS AND METHODS: Two hundred eighty posts were divided into seven groups of 40, one group for each type of post analyzed. Within each group, 15 posts were subjected to three-point bending strength test, 15 to a microhardess meter for the Knoop hardness, and 10 to Scanning Electron Microscope in order to determine the diameter of the fibers and the percentage of fibers embedded in the matrix. To compare the flexural strength in relation to the type of fiber, matrix, and the hardness of the posts, a Kruskal-Wallis H test was used. The Jonckheere-Terpstra test was used to determine if the volume percent of fibers in the post influenced the bending strength. RESULTS: The flexural strength and the hardness depended on the type of fibers that formed the post. The lower flexural strength of a post could be due to deficient bonding between the fiber and the resin matrix. CONCLUSION: According to the results, other factors, besides the microstructural characteristics, may also influence the mechanical properties of the post. The feature that has more influence on the mechanical properties of the posts is the type of fiber.