Is composite repair suitable for anterior restorations? A long-term practice-based clinical study.

OBJECTIVES: This study investigated the impact in survival, when repair is seen as failure or not, in anterior composite restorations with a retrospective 15-year follow-up study. MATERIALS AND METHODS: Data was collected from patients' files of a private dental practice, including patients with direct composite restorations placed in anterior teeth (class III, class IV, or veneer) between January 1994 and December 2009. Data were analyzed considering or not repair as failure. Statistical analysis was performed with log rank test, Kaplan-Meier, and Cox regression (p < .05). RESULTS: One hundred forty-four patients' files were included, with 634 restorations. At 15 years, Class III / IV restorations showed 69% survival and 2.4% annual failure rate (AFR) when repair was not considered as failure, and 64% and 2.9% AFR, respectively, when repair was seen as failure. For direct veneers, at 5 and 10 years of follow-up, survival dropped from 85% to 74% and from 52% to 38% respectively, when repair was considered as failure. In general, restorations placed in the upper jaw showed increased risk for failure compared to the lower jaw (p < .01), and restorations in central incisors presented a higher risk for failure compared to canines (p < .01). CONCLUSION: Composite repair seems a suitable alternative for class III, class IV, and veneer restorations since it was able to increase the survival of restorations performed in anterior teeth. CLINICAL RELEVANCE: Composite repair for anterior restorations is a suitable restorative treatment option and presents benefits over replacement, including the preservation of sound tooth structures, reduced clinical chair time, and patient anxiety.

Influence of the Inoculum Source on the Cariogenicity of in vitro Microcosm Biofilms.

This study investigated the cariogenic potential of biofilms originating from different types of inoculum (saliva and dental plaque) from caries-active and caries-free individuals. Ten volunteers were selected from each caries condition for the paired collection of saliva and dental plaque. Microcosm biofilms were grown in triplicate from each inoculum on enamel specimens in 24-well plates under cariogenic challenge. After 10 days, the biofilms were collected for analysis of outcome variables: percentage of surface hardness change (%SHC) and microbiological composition of biofilms. Statistical analysis was performed using the t test, the linear multivariate analysis model and Pearson's correlation coefficients (α = 0.05). A comparative analysis between microbiological baseline data showed higher counts of mutans streptococci in plaque samples within caries-active individuals; a comparative analysis of colony-forming unit (CFU) counts between individuals with different caries status showed higher counts of acid-tolerant microorganisms and mutans streptococci in dental plaque and of acid-tolerant microorganisms in saliva. After 10 days of biofilm growth, the CFU values for total microorganisms, lactobacilli, mutans streptococci and acid-tolerant bacteria, as well as for SHC, were not statistically significant, considering the type of inoculum and caries condition (p > 0.05). A positive correlation was found for %SHC and CFU counts of acid-tolerant bacteria (r = 0.406) and lactobacilli (r = 0.379). Under the limits of this study, the cariogenic potential of biofilms, formed under identical conditions in vitro, is similar, regardless of baseline differences between the source and type of inoculum.

Secondary Caries Development in in situ Gaps next to Composite and Amalgam.

This in situ study investigated the secondary caries development in dentin in gaps next to composite and amalgam. For 21 days, 14 volunteers wore a modified occlusal splint containing human dentin samples with an average gap of 215 µm (SD=55 µm) restored with three different materials: Filtek Supreme composite, Clearfil AP-X composite and Tytin amalgam. Eight times a day, the splint with samples was dipped in a 20% sucrose solution for 10 min. Before and after caries development, specimens were imaged with transversal wavelength independent microradiography, and lesion depth (LD) and mineral loss (ML) were calculated. The LD and ML of the three restoration materials were compared within patients using paired t tests (α=5%). In total 38 composite samples (Filtek n=19 and AP-X n=19) and 19 amalgam samples could be used for data analysis. AP-X composite presented the highest mean values of LD and ML of the three restorative materials. Amalgam showed statistically significantly less ML (Δ=452 µm×vol%) than the combined composite materials (p=0.036). When comparing amalgam to the separate composite materials, only AP-X composite showed higher ML (Δ=515 µm×vol%) than amalgam (p=0.034). Analysis of LD showed the same trends, but these were not statistically significant. In conclusion, amalgam showed reduced secondary caries progression in dentin in gaps compared to composite materials tested in this in situ model.

A biofilm cariogenic challenge model for dentin demineralization and dentin bonding analysis.

OBJECTIVES: This study was designed to adapt a previously developed in vitro microcosm biofilm model to create carries-affected dentin (CAD) and establish conditions for using the model in bonding studies. MATERIALS AND METHODS: Biofilms were originated from human saliva and grown on dentin discs for 0 (sound dentin), 3, 5, 7, 14, or 21 days under intermittent cariogenic condition (n = 10). At each time point, composite cylinders were bonded to the dentin using self-etch adhesive (Clearfil SE Bond). The response variables were integrated mineral loss (ΔS), lesion depth (LD), shear bond strength (SBS), and failure mode. Data were statistically analyzed (α = 0.05). Bonded interfaces were analyzed by scanning electron microscopy (SEM), and dentin surfaces characterized by infrared spectroscopy (Fourier transform infrared spectroscopy, FTIR). RESULTS: Lower ΔS was found for sound dentin than for CAD in all experimental groups, except for the group under cariogenic challenge for 3 days. The SBS to CAD was significantly lower than control for all cariogenic challenge times. Adhesive failures were predominant in all groups. ΔS and LD had a significant negative correlation with SBS. A significant exponential decay in SBS was associated with increased ΔS values. CAD had lower mineral and amide I content and an irregular hybridization interface compared to sound dentin. CONCLUSIONS: The microcosm biofilm model was able to artificially induce CAD, which imposed challenge to the bonding of the polymeric adhesive material. CLINICAL RELEVANCE: Presence of CAD might interfere with the bonding of polymeric materials. The microcosm biofilm model proposed could be useful for preclinical dentin bonding studies.

Chapter 9.4: Operative Treatment and Monitoring of Coronal Caries in Daily Practice.

After the caries lesion reaches a certain extent of tooth structure loss, a restoration is often needed to repair the defect. Operative interventions in cariology aim to aid biofilm removal and lesion arrest by cavity sealing, avoid pulpal damage, and restore form, function, and esthetics. There are no clear evidence-based parameters to determine the most appropriate treatment option for each clinical situation. Despite of this, direct composite resins have been the preferable restorative treatment. Scientific literature shows that composites and adhesive strategies play a minor role in treatment success. Patient-related risk factors (mainly those associated with lifestyle and health choices), in addition to the dentist's decision-making process, play a significant role in longevity of the restorations, which tend to fail for the same reasons that lead to the need for restoration (dental caries, tooth/restoration fracture, and esthetics). Therefore, monitoring old restorations in clinical service, even if those present clear signs of degradation, is possible and reasonable within the concept of minimal intervention in dentistry. Unnecessary reinterventions are harmful and costly to health systems, and the clinician's efforts must be directed to eliminating or reducing the etiological factors that can cause the restoration to fail. Thus, patient risk factors assessment is a crucial point in monitoring restorations. Clinician should - whenever possible - postpone operative reinterventions, monitoring the etiological factors that may compromise the restoration's longevity. Also, when operative reintervention is necessary, refurbishment, polishing, and repair should be prioritized over replacement.

18-year survival of posterior composite resin restorations with and without glass ionomer cement as base.

OBJECTIVE: Advantages and disadvantages of using intermediate layers underneath resin-composite restorations have been presented under different perspectives. Yet, few long-term clinical studies evaluated the effect of glass-ionomer bases on restoration survival. The present study investigated the influence of glass-ionomer-cement base in survival of posterior composite restorations, compared to restorations without base. METHODS: Original datasets of one dental practice were used to retrieve data retrospectively. The presence or absence of an intermediate layer of glass-ionomer-cement was the main factor under analysis, considering survival, annual failure rate and types of failure as outcomes. Other investigated factors were: patient gender, jaw, tooth, number of restored surfaces and composite. Statistical analysis was performed using Fisher's exact test, Kaplan-Meier method and multivariate Cox-regression. RESULTS: In total 632 restorations in 97 patients were investigated. Annual failure rates percentages up to 18-years were 1.9% and 2.1% for restorations with and without base, respectively. In restorations with glass-ionomer-cement base, fracture was the predominant reason for failure, corresponding to 57.8% of total failures. Failure type distribution was different (p=0.007) comparing restorations with and without base, but no effect in the overall survival of restorations was found (p=0.313). SIGNIFICANCE: The presence of a glass-ionomer-cement base did not affect the survival of resin-composite restorations in the investigated sample. Acceptable annual failure rates after 18-years can be achieved with both techniques, leading to the perspective that an intermediate layer, placed during an interim treatment, may be maintained without clinical detriment, but no improvement in survival should be expected based on such measure.

The influence of different restorative materials on secondary caries development in situ.

OBJECTIVES: The effect of direct restorative materials on caries lesion formation was investigated with an 8-week in situ study with split-mouth design, testing the hypothesis that no difference in mineral loss next to a restoration would be found between different composite-based-materials and amalgam. METHODS: Six groups (n=18) of restored dentine samples were prepared using amalgam, a microhybrid, a nanohybrid and a silorane composite. The composites were adhesively bonded with systems with or without an antibacterial monomer (Clearfil-SE-Protect, Clearfil-SE-bond, respectively), except for the silorane group (Silorane-System-Adhesive). Non-restored dentine samples were used as control (primary caries). Samples were inserted into slots, in lower prosthesis especially made for the experiment. Subjects were instructed to dip the lower prosthesis in a sucrose solution 4 times per day. At baseline and 8 weeks, samples were radiographed extra-orally and the integrated mineral loss was calculated. Data were statistically analyzed using multiple linear regression with a multilevel model (p=0.05). RESULTS: Nine subjects were selected, and only outer lesions were observed. The hypothesis was partially rejected, as the microhybrid composite bonded with the antibacterial system and the nanohybrid composite presented statistically significant lower mineral loss compared to amalgam. Also, no significant differences were seen for these groups compared to control. CONCLUSION: Within the limits of this study, the restorative material may influence outer lesion progression. Amalgam was not found to be related to lower secondary caries progression in dentine compared to composite-based materials after 8 weeks in situ. CLINICAL SIGNIFICANCE: Although patient factors play a major role in caries progression, the restorative material may affect outer secondary lesion progression.