Predictors of procedural errors in class II resin composite restorations using bitewing radiographs

Objective

To identify the potential factors that induce procedural errors during posterior proximal resin composite restorations placed by dental students.

Materials and Methods

This retrospective study evaluated 803 bitewing radiographs of posterior proximal resin composite restorations placed by dental students at Imam Abdulrahman bin Faisal University. Atypical radiographic signs of failure were screened, and different patient-, operator-, and clinical-related factors were recorded. Chi-square test was used to examine the relationship between procedural errors and recorded factors. Stepwise adjusted logistic regression model was performed to identify predictors of procedural errors.

Results

The most observed errors were internal gaps at the bonding interface and internal voids. Molars had 0.39 the risk of internal voids (odds ratio [OR] = 0.39; confidence interval [CI] = 0.25-0.60; P = <0.0001), 0.41 the risk of sharp angle (OR = 0.41; CI = 0.24-0.68; P = <0.001), and 0.57 the risk of open contact (OR = 0.57; CI = 0.34-0.97; P = 0.04) compared to premolars. Those who were >40 years of age had 1.79 the risk of overhang compared to younger patients (OR = 1.79; CI = 1.04-3.11; P = <0.04). First molars and premolars had 0.64 the risk of overhang compared to second molars and premolars (OR = 0.64; CI = 0.41-1.00; P = 0.04). Junior students had 1.97 the risk of internal gap compared to their senior counterparts (OR = 1.97; CI = 1.20-3.21; P = 0.008). Mesial restorations had 0.38 the risk of external gap compared to mesio-occluso-distal (MOD) restorations (OR = 0.38; CI = 0.19-0.78; P = 0.003). Restorations with a margin coronal to the cemento-enamel junction (CEJ) had 0.44 the risk of external gap compared to those restorations with a margin apical to the CEJ (OR = 0.44; CI = 0.29-0.66; P = <0.0001).

Conclusion

Our findings suggested a higher incidence of procedural errors in restoring premolars and MOD cavity preparations. Therefore, it is crucial to enhance the comprehensiveness of laboratory training and expose students to diverse clinical scenarios and various techniques.

Is surface roughness of direct resin composite restorations material and polisher-dependent? A systematic review

STATEMENT OF PROBLEM

Direct resin composite bonding offers a highly esthetic, minimally invasive option for the treatment of anterior teeth however the challenge to improve their longevity remains. Direct resin composite restorations are limited by the risk of staining which may be influenced by the final surface roughness (Ra) of composite achieved.

PURPOSE

The purpose of this review is to investigate, using a systematic approach, whether the final surface roughness of anterior composite restorations is affected by the interaction between resin composite and polishing systems.

MATERIALS AND METHODS

The review was conducted by 3 independent reviewers and included articles published up to January 21, 2021. Three electronic databases were searched: Medline, Embase, and Web of Science. Studies assessing a quantitative effect of polishing methods on the Ra of direct composite resin materials published after the year 2000 and restricted to the English language were included.

RESULTS

The database search for the effect of polishing systems on composite materials retrieved 125 eligible studies. Twelve duplicate records were removed. The resulting records were screened using title and abstract leading to 38 reports which were sought for retrieval. Application of eligibility criteria led to 11 studies included in the review. Hand searching of these studies yielded no additional papers.

CONCLUSIONS

There is insufficient evidence to determine whether combination of composite and polisher influences final Ra. More research is required to determine if there is an optimum combination of polisher and composite.

CLINICAL IMPLICATIONS

Polishing should be completed following planned finishing procedures. The approximation to the final surface and which finishing burs to use, if any, should be considered when planning a restoration. Durafill VS predictably achieves an acceptable Ra by different polishers.

Anterior Matrix Systems for Composite Restorations: A Review

In the field of restorative dentistry, composite resins have emerged as the most utilized materials. They revolutionized the cosmetic approach to anterior tooth treatment since their introduction to dental practice. In cases where one or more of the tooth's walls are absent, matrices are employed to assist in the creation of the proper anatomic contour and proximal contacts without the occurrence of gingival overhangs. Matrices come in a variety of designs suitable for various therapeutic conditions. Depending on the level of tooth destruction, they might range from a simple metal or plastic strip to a circumferential ring of metal surrounding the entire crown. Although the handling characteristics of modern composites have significantly improved, dentists still encounter challenges with the development of good interproximal contact and proper anatomical contour. The utilization of an anterior matrix system can be paramount in achieving these objectives.

Viscosity modulation of resin composites versus hand application on internal adaptation of restorations

OBJECTIVE

To compare the effect of the injection of viscosity modulated resin composites versus hand application without modulation, on the internal adaptation of different material to the gingival wall of class II preparations.

MATERIALS AND METHODS

Class II cavities were created on mesial and distal surfaces of 60 extracted human molars, resulting on 120 tooth preparations (n = 120). The preparations were restored with four resin composites: VIS-VisCalor (Voco); GRA-GrandioSO (Voco); FIL-Filtek One Bulk Fill (3 M/ESPE); and SON-SonicFill (Kerr). Each composite was applied by two different techniques: by hand (H) or assisted (A). For the hand technique, the material was placed into the preparation using a spatula. For the assisted technique, the resin composite was heated up to 65 °C (for VIS, GRA, and FIL) or sonicated (for SON) and injected into the preparation. After the restorative procedures, the teeth were completely demineralized to allow the restoration removal. The total area of the gingival wall and the area occupied by interfacial defects of adaptation (TDA) were measured by optical microscopy and digital software. The percentage of the area occupied by the defects (%TDA) in relation to the total area was calculated. The data were analyzed by two-way ANOVA and Tukey tests.

RESULTS

Significant differences were observed for the application technique (p = 0.0403) and for the materials (p = 0.0184), as well for the interaction between them (p = 0.0452). The mean (standard deviation) of %TDA and results of Tukey test for the interaction were as follows: SON/H - 1.04(0.75)a; VIS/A - 2.01(0.92)a; VIS/H - 3.62(0.99)b; GRA/A - 6.23(3.32)b; FIL/H - 7.45(3.31)bc; GRA/H - 9.21(4.53)c; SON/A - 11.26(4.04)a; FIL/A - 17.89(5.08)d.

CONCLUSION

The injection of heated resin composites improves the adaptation to the walls in relation to the hand technique for VisCalor and GrandioSO but worsens for Filtek One. Sonic vibration increases the number of interfacial defects for SonicFill.

CLINICAL RELEVANCE

The physical modulation of the resin composite viscosity can improve or worsen the material adaptation to the walls of class II restoration. It had a positive impact for VisCalor and GrandioSO but a negative for Filtek One and SonicFill.

Hardness Development in Resin Composite Core Materials

PURPOSE

To investigate the hardness characteristics of 13 contemporary resin core materials.

MATERIALS AND METHODS

Specimens (n = 12) were fabricated using stainless steel molds with top surfaces of dual-cure products photopolymerized while additional groups were allowed to self-cure. Twelve Knoop hardness indentations 500 microns apart were obtained of photopolymerized top and bottom sample surfaces as well as the self-cured sample surface with the mean recorded as the representative sample hardness. Testing was completed at 10 minutes, 1 hour, and 24 hours. In addition, hardness values were compared to that obtained from polished coronal dentin samples. Mean data between groups were analyzed with Kruskal-Wallis/Dunn's, within groups with repeated measures ANOVA/Tukey's.

RESULTS

Hardness results were material dependent. All but two products demonstrated a 0.8 bottom/top Knoop hardness ratio at 10 minutes. Product's self-cure cure reaction did not attain hardness similarity with any photopolymerized top surfaces and while some materials were found to have similar dentin hardness to resin top surface ratio similarity, only one product had hardness equal to or greater than that of dentin during any time period.

CONCLUSIONS

Under this study's conditions, hardness development was material dependent and all but two products demonstrated adequate hardness-derived degree of cure assessment at 10 minutes after preparation. Self-cured samples demonstrated hardness increase; however, no self-cured material achieved hardness similarity to photopolymerized top surfaces. None of the materials achieved hardness similarity to dentin and only one product demonstrated hardness greater than that of dentin.

Microtomographic Analysis of Resin Composite Core Material Porosity

PURPOSE

To nondestructively evaluate the porosity of ten contemporary resin composite core materials using microtomographic (microCT) analysis.

MATERIAL AND METHODS

Resin composite core material samples (n = 12) including dual-cure, visible light cure only, and a self-cure material were fabricated using a standardized mold following manufacturer's recommendations. After storage in phosphate buffered saline for one week, specimens were analyzed using a microCT unit at 5.3-µm resolution over a rotational range of 360°. Image 3D recombination and analysis was accomplished using microCT software. Evaluated parameters included material volume investigated, closed pore number and volume, as well as closed pore percentage. Parameter mean values were evaluated with Kruskal-Wallis/Dunn at a 95% confidence level (α = 0.05).

RESULTS

Mean percent total porosity with standard deviation identified significant differences in decreasing order as Ti-Core: 2.2 (0.4) > Ti-Core Auto E: 1.3 (0.3) = Ti-Core Flow Plus: 1.1 (0.02) > Clearfil Photo Core: 0.94 (0.5) = Clearfil DC Core Plus: 0.6 (0.18) = MultiCore Flow: 0.58 (0.1) > Fluorocore 2+: 0.14 (0.2) = Build-It FR: 0.068 (0.02) = Gradia Core: 0.03 (0.02) = Rebilda DC: 0.02 (0.01). A pilot microCT evaluation evaluating a mixing tip revealed incomplete mixture between the two resins with porosity introduced from turbulence as the materials are forced through the tip during preparation.

CONCLUSIONS

A wide range of porosity was identified between the ten materials evaluated. These preliminary results warrant more investigation evaluating additional resin composite core materials, the preparation capabilities of automix tips, and porosity presence in the unmixed materials.

Characterization and Comparative Analysis of Voids in Class II Composite Resin Restorations by Optical Coherence Tomography

PURPOSE

This study aimed to characterize and analyze the number of voids and the percentage of void volume within and between the layers of class II composite restorations made using the bulk fill technique or the incremental technique by optical coherence tomography (OCT).

METHODS AND MATERIALS

Class II cavities (4×4×2 mm) were prepared in 48 human third molars (n=24 restorations per group, two class II cavities per tooth). Teeth were divided into four groups and restored as follows: group 1 (FOB), bulk filled in a single increment using Filtek One Bulk Fill (3M Oral Care); group 2 (FXT), incrementally filled using four oblique layers of Filtek Z350 XT (3M Oral Care); group 3 (FBF+FXT), bulk filled in a single increment using Filtek Bulk Fill Flowable Restorative (3M Oral Care) covered with two oblique layers of Filtek Z350 XT (3M Oral Care), and group 4 (FF+FXT), incrementally filled using Filtek Z350 XT Flow (3M Oral Care) covered with two oblique layers of Filtek Z350 XT (3M Oral Care). After the restorative procedure, specimens were immersed into distilled water and stored in a hot-air oven at 37°C. Forty-eight hours later, thermal cycling was conducted (5000 cycles, 5°C to 55°C). Afterward, OCT was used to detect the existence of voids and to calculate the number of voids and percentage of voids volume within each restoration. Data were submitted to chi-square and Kruskal-Wallis tests (α=0.05). Comparisons were made using the Dunn method.

RESULTS

Voids were detected in all groups, ranging from 0.000002 (FBF+FXT and FF+FXT) to 0.32 mm³ (FBF+FXT). FF + FXT presented voids in all of the restorations and had a significantly higher number of voids per restoration when compared to the other groups (p<0.05), but restorations with the presence of voids were significantly higher only when compared to FXT (p<0.05). FBF + FXT presented a significantly higher percentage of voids volume than that of FXT (p<0.05). When comparing restorations made using high-viscosity resin-based composites (FOB and FXT), no significant differences regarding number of voids or percentage of voids volume were detected (p≥0.05).

CONCLUSIONS

The use of flowable resin-based composites can result in an increased number of voids and percentage of voids volume in restorations, and this appears to be more related to voids present inside the syringe of the material than to the use of incremental or bulk fill restorative techniques.

Effects of adhesive used as modeling liquid on the stability of the color and opacity of composites

OBJECTIVE

This study evaluated the effects of adhesive type used as modeling liquid on the stability of the color and opacity of composites submitted to thermal cycling in staining solutions followed by a bleaching procedure.

METHODS

Thirty cylinder-shaped composite specimens (10 mm diameter × 1.5 mm thickness) were built using or not using (control) an adhesive (Adper Universal or Scotchbond Multipurpose) as the modeling liquid. After polishing procedures, the color and opacity were measured, and the specimens were submitted to 200 thermal cycles with 10 s of dwell time in baths of grape juice at 5°C, water at 37°C, and coffee at 55°C. Changes in opacity and color caused by the staining solutions were measured. Then, the specimens were bleached with 35% hydrogen peroxide for 45 minutes followed by color/opacity measurements. Data were analyzed by ANOVA and Tukey's test (α = 0.05).

RESULTS

The use of modeling liquids did not affect the initial color and opacity of composite. Reduced changes to color (E₀₀  = 3.44) and opacity (+2.67%) were observed for specimens modeled using Adper Universal. Bleaching procedures reduced the color (E₀₀  = 1.9-3.8) and opacity (-2.3 to 3.1%) alterations caused by staining solutions but were unable to restore the values observed at baseline.

CONCLUSION

The use of universal adhesive as modeling liquid significantly reduced the color and opacity changes caused by staining solutions, and the bleaching procedure partially re-established the opacity and color of the composites.

CLINICAL SIGNIFICANCE

This study evaluates whether using adhesive systems for modeling a composite affects the color and opacity changes caused by staining solutions followed by a bleaching procedure. The findings suggest that the use of a universal adhesive as modeling liquid can reduce the alterations in optical properties caused by staining solutions, and the application of high-concentrated hydrogen peroxide over the composite reduce the color changes without fully recover the initial color.

Use of dental adhesives as modeler liquid of resin composites

OBJECTIVES

Resin adhesives (RA) have been applied between resin composite (RC) increments, but there is no consensus on the impact of this technique on the properties of the final restoration. This study evaluated the effect of the presence of RA between RC layers on physical properties, translucency and long-term color stability of the restorative material.

METHODS

Scotchbond™ Multi-Purpose (bond, 3M ESPE) and Adper™ Single Bond 2 (3M ESPE) were used as RA, and Filtek™ Z350 (3M ESPE) as RC. Specimens containing RA were prepared by applying 3 layers of the adhesive between 4 increments of RC; adhesive-free specimens were also used (control). Tests of water sorption and solubility, mechanical performance (microtensile cohesive strength, flexural strength, and flexural modulus, after immediate and long-term water storage), and translucency and color stability (after immediate and 1, 7, 90, and 180 days of water or wine storage) were performed. Scanning electron microscopy (SEM) images were also taken from the fractured specimens (flexural strength test). Data were analyzed using ANOVA and Tukey test (p<0.05).

RESULTS

Scotchbond (SBMP) showed lower water sorption and solubility than the control (p<0.001), and an overall similar (p≥0.198, immediate tests) or higher (p≤0.019, long-term tests) mechanical performance. SBMP exhibited a rougher cross-sectional surface compared to the other groups. Translucency remained unaltered after 180 days of storage (p≥0.313), except for single bond that had increased translucency with wine storage (p<0.045). After 180 days, all groups changed color (p≤0.002), although more intensively when immersed in wine.

SIGNIFICANCE

The presence of RA within RC increments increased the physical stability of the material, being this effect more evident by using the hydrophobic unfilled adhesive resin (SBMP). This study is the first to show positive results from the use of resin adhesives as modeler liquid of resin composite, which is common in clinical practice.

Conservative Approach for the Esthetic Management of Multiple Interdental Spaces: A Systematic Approach

PURPOSE

To describe a conservative approach using resin-based composites following a buccolingual layering technique with a customized silicon index for the management of multiple diastemas.

CLINICAL CONSIDERATIONS

This clinical article describes the case of a patient with their anterior teeth esthetically compromised by multiple diastemas, incisal wear, and dull/low-value cervical composite resin restorations that were managed with nanofilled composite resin using the "buccolingual technique" with a customized silicon index made from a wax-up to build up the restorations. The first layer of composite placed lingually that represents the enamel replacement was placed directly on the silicon index so that it provides in one single step the lingual profile and the position of the incisal edge of the restoration. Then, dentine and effect composite resin can be applied in a precise three-dimensional configuration.

CONCLUSIONS

To solve esthetic dental problems, as anterior diastemas, in a very conservative and even reversible way, the use of direct resin composites for layering is an excellent choice, but should be performed based on simple and reproducible techniques, as the buccolingual technique.

CLINICAL SIGNIFICANCE

The clinical technique described in this paper shows the advantages of a conservative approach to correct diastemas on maxillary anterior teeth. The application of these techniques can not only help achieve optimal esthetics, but also avoid the removal of extensive dental hard tissue and achieve a predictable final result, especially in esthetically demanding cases.