Occlusal Region Research Articles

Analysis of correlation between optical and microtomography measurements of cementation space in CAD-CAM ceramic crowns

Statement of problemIdentical computer-aided design (CAD) parameters may be used to mill a variety of ceramic materials for computer-aided design and computer-aided manufacture (CAD-CAM) crowns. Whether milled crown spacing matches the designed parameters when more than a single evaluation method is applied is unknown. PurposeThe purpose of this in vitro study was to correlate the stereomicroscope and the microcomputer tomography (μCT) 2-dimensional analysis of the cementation space with the replica technique in assessing 3 different ceramic materials. Material and methodsThe specimens were milled in lithium disilicate, resin nanoceramic, and zirconia (n=30). The cement space was measured at the marginal, axial, and occlusal regions. One hundred twenty measurements of each material were used to correlate the methodologies. Data were statistically evaluated with 2-way repeated measures ANOVA and the Tukey test (α=.05). The Pearson correlation coefficient was used for each region for both methodologies (μCT and optical microscopy) separately. ResultsFor the μCT analysis, no differences were observed (P>.05) among the materials, but the axial region showed a positive correlation with the marginal (r=0.957) and occlusal regions (r=0.349); the same was observed between the occlusal and marginal regions (r=0.338). However, for stereomicroscope evaluation, resin nanoceramic and zirconia present similar cementation space (P=960), both being different from lithium disilicate (P<.05). The marginal region presented a positive correlation with axial (r=0.149) and occlusal regions (r=0.344), but the axial region showed negative correlation with the occlusal surface (r=−0.205). ConclusionsThe measurements of the scanned replicas were accurate when thinner sections were under measurement. Although the same space parameters were set in the CAD software program, definitive internal dimensions varied among the milled crowns.

Maxillary molar enamel thickness of Plio-Pleistocene hominins

Enamel thickness remains an important morphological character in hominin systematics and is regularly incorporated into dietary reconstructions in hominin species. We expand upon a previous study of enamel thickness in mandibular molars by examining a large maxillary molar sample of Plio-Pleistocene hominins (n = 62) and a comparative sample of extant nonhuman apes (n = 48) and modern humans (n = 29). 2D mesial planes of section were generated through microtomography, and standard dental tissue variables were measured to calculate average enamel thickness (AET) and relative enamel thickness (RET). AET was also examined across the lingual, occlusal, and buccal regions of the crown. This study confirms previous findings of increasing enamel thickness throughout the Plio-Pleistocene, being thinnest in Australopithecus anamensis and peaking in Australopithecus boisei, with early Homo specimens, exhibiting intermediate enamel thickness. Agreeing with previous findings, 2D plane of section enamel thickness is found to be a poor taxonomic discriminator, with no statistically significant differences observed between fossil hominins. For fossil hominins, modern humans, and Pongo, the occlusal region of enamel was the thickest, and the lingual enamel thickness was greater than buccal. Pan and Gorilla present the opposite pattern with enamel being thinnest occlusally. Comparison at each molar position between the maxilla and mandible revealed very few significant differences in fossil hominins but some evidence of significantly thicker maxillary enamel (AET) in modern humans and thinner maxillary enamel in Pan (RET).

Surgically Assisted Rapid Palatal Expansion to Correct Maxillary Transverse Deficiency.

Background:Transverse maxillomandibular discrepancies are widespread. Treatment is comprised of orthodontic expansion in patients younger than 15 years or by surgically assisted rapid palatal expansion (SARPE) in skeletally mature patients where the possibility of successful orthodontic maxillary expansion decreases as sutures close and resistance to mechanical forces increases.Aim:To present our experience of treating transverse maxillary deficiency using a unique L-shaped osteotomy and to demonstrate stable results.Patients and Methods:32 patients aged between 19 and 54 years exhibiting transverse maxillary deficiency. L-shaped osteotomy was performed laterally from the pterygoid plate posteriorly to above the roots of the second incisive anteriorly continuing with a vertical osteotomy between the lateral incisive and canine teeth toward the horizontal osteotomy. In 18 patients with dysgnathia, bimaxillary surgery was performed one year following the SARPE procedure.Results:Mean transverse maxillary expansion of 6.2mm at the canine incisal and 6.4mm at the first molar occlusal regions were obtained. One year postoperatively results were relatively stable, 5.8mm and 6.2mm respectively. The SARPE procedure resulted in overcoming the maxillary buttress resistance, expansion of the anterior dental arch and bilateral distraction creating bone on both sides of the premaxilla contributing to better alignment of the anterior teeth and superior stability.Conclusions:We conclude that SARPE is an effective and stable method for addressing severe maxillary transverse discrepancy in adults while the unique osteotomy performed allowed for maintaining proper position of the premaxilla and maxillary midline and allowing for division of the newly created bone bilaterally thus resulting in a more stable outcome.

Quantitative tooth mobility evaluation based on intraoral scanner measurements.

Tooth mobility assessment is subjective and current techniques require the translation of a continuous variable to a categorical variable based on the perception of the examiner. The aim of this study was to evaluate the reliability of a novel technique to assess tooth mobility. Three experienced periodontists were asked to push tooth #16 into a buccal position to in a typodont model with different mobility (M1-M2). Tooth position was obtained using an intraoral scanner and files were compared in metrology software. Mobility was calculated at three reference points at the cervical (C), middle (M), and occlusal (O) regions of the buccal surface of the tooth to determine the linear deviation in the three axes (x, y, and z). Reliability was determined by intraclass-correlation coefficient, differences between M1 and M2 determined by t test, and the analysis of variance (ANOVA) was used to compare the data at the C-M-O regions. Excellent reliability was assessed by Cronbach alpha >0.9 on the x-y-z axes for both mobility tested, except for M1-C X (0.85), M1-M Y (0.89), and M2-M Z (0.89). The correlation between the examiners demonstrated excellent (˃0.90) or good (0.75˃ x ˂0.90) consistency, except for M1-C Y (0.73; examiner 1 to 2) and M1-M X (0.69; examiners 1 to 3). Significant changes were detected in all axes at the three reference points comparing M1 and M2, and a similar proportional change was observed between O-M-C reference points for M1 and M2. A novel technique to assess tooth mobility based on intraoral scanner measurements provided reliable data in an in vitro experiment.

The effect of 1.5 T and 3 T magnetic resonance imaging on microleakage of amalgam restorations.

The aim of this article is to compare the effects of 1.5 T and 3 T MRI on microleakage of amalgam restorations. A total of 90 extracted molar teeth were used in this study. Amalgam was used to restore standard Class V preparations (5 × 3 × 2 mm). Following the restoration, the teeth were divided into three groups according to magnetic resonance imaging (MRI) protocol (Group I: Control, Group II: 1.5 T MRI, and Group III: 3 T MRI). A total of 6,000 thermal cycles at 5°C-55°C were applied on all samples. Microleakage values were measured in millimeters using the ImageJ program. Microleakage values were higher in the gingival region compared to the occlusal region in all groups and the differences were statistically significant (p < .05). Microleakage values were not statistically different among the groups in the occlusal region (p > .05), while there were statistically significant differences among the groups with respect to microleakage values in the gingival region (p < .01). The highest mean microleakage amount in the gingival region was measured in Group III (1.192 ± 0.941 mm). This was followed by Group II (0.519 ± 0.813 mm) and Group I (0.347 ± 0.726 mm), respectively. Within the limitations of this in vitro study, we observed that higher microleakage values in amalgam restored teeth in which were exposed to MRI procedure. We also found that the teeth exposed to the stronger magnetic field showed higher microleakage amount.

A Comparison Study of Marginal and Internal Fit Assessment Methods for Fixed Dental Prostheses.

Numerous studies have previously evaluated the marginal and internal fit of fixed prostheses; however, few reports have performed an objective comparison of the various methods used for their assessment. The purpose of this study was to compare five marginal and internal fit assessment methods for fixed prostheses. A specially designed sample was used to measure the marginal and internal fit of the prosthesis according to the cross-sectional method (CSM), silicone replica technique (SRT), triple scan method (TSM), micro-computed tomography (MCT), and optical coherence tomography (OCT). The five methods showed significant differences in the four regions that were assessed (p < 0.001). The marginal, axial, angle, and occlusal regions showed low mean values: CSM (23.2 µm), TSM (56.3 µm), MCT (84.3 µm), and MCT (102.6 µm), respectively. The marginal fit for each method was in the range of 23.2–83.4 µm and internal fit (axial, angle, and occlusal) ranged from 44.8–95.9 µm, 84.3–128.6 µm, and 102.6–140.5 µm, respectively. The marginal and internal fit showed significant differences depending on the method. Even if the assessment values of the marginal and internal fit are found to be in the allowable clinical range, the differences in the values according to the method should be considered.

Comparative Study of the Trueness of the Inner Surface of Crowns Fabricated from Three Types of Lithium Disilicate Blocks

This study set out to compare the three-dimensional (3D) trueness of crowns produced from three types of lithium disilicate blocks. The working model was digitized, and single crowns (maxillary left second molar) were designed using computer-aided design (CAD) software. To produce a crown design model (CDM), a crown design file was extracted from the CAD software. In addition, using the CDM file and a milling machine (N = 20), three types of lithium disilicate blocks (e.max CAD, HASS Rosetta, and VITA Suprinity) were processed. To produce a crown scan model (CSM), the inner surface of each fabricated crown was digitized using a touch-probe scanner. In addition, using 3D inspection software, the CDM was partitioned (into marginal, axis, angular, and occlusal regions), the CDM and CSM were overlapped, and a 3D analysis was conducted. A Kruskal–Wallis test (α = 0.05) was conducted with all-segmented teeth with the root mean square (RMS), and they were analyzed using the Mann–Whitney U-test and the Bonferroni correction method as a post hoc test. There was a significant difference in the trueness of the crowns according to the type of lithium disilicate block (p &lt; 0.001). The overall RMS value was at a maximum for e.max (42.9 ± 4.4 µm), followed by HASS (30.1 ± 9.0 µm) and then VITA (27.3 ± 7.9 µm). However, there was no significant difference between HASS and VITA (p = 0.541). There were significant differences in all regions inside the crown (p &lt; 0.001). There was a significantly high trueness in the angular region inside the crown (p &lt; 0.001). A correction could thus be applied in the CAD process, considering the differences in the trueness by the type of lithium disilicate block. In addition, to attain a crown with an excellent fit, it is necessary to provide a larger setting space for the angular region during the CAD process.

Una perspectiva de la microfiltración marginal en restauraciones de resina compuesta de clase II usando diferentes tipos y técnicas: un estudio in-vitro.

The study aimed to introduce a perspective of the essential reason behind why marginal microleakage develops regardless of the composite type, the technique, or the bonding system applied, especially in gingival floor of class II cavities. Materials and Methods: Three types of composite resin materials (CharmfilTM, ParaFillTM, and ProMedica®) were used to evaluate microleakage of class II restorations using two restorative approaches. Twenty four newly extracted bicuspid teeth were divided into two main groups (n=12 each) according to the restoration technique (open or closed sandwich techniques). Teeth of each group were then divided into 3 groups (n= 4 each) according to the type of the composite resin used. The restorations were then subjected to a thermocycling process and then were immersed into methylene blue solution for 12 hours. Mesiodistal sectional cuts were made along the central grooves and assessed under stereomicroscope for marginal microleakage. The data were statistically analyzed with a p-value &lt;0.05 considered significant. Results: There were no statistically significant differences in marginal microleakage between the three examined groups using both techniques (p&gt;0.05). Under the microscope, the marginal microleakage was more obvious at the cervical region than at the occlusal region. Conclusion: There was no effect of the composite type or the application technique used on the occurrence of marginal microleakage. The first portion of the material applied against the cavity floor is the primary factor involved in possibly minimizing marginal microleakage.

Optical pH measurement system using a single fluorescent dye for assessing susceptibility to dental caries.

.Sugar-rich diets and poor dental hygiene promote the formation of a biofilm (plaque) that strongly adheres to the dental enamel surface and fosters the evolution of aciduric bacteria. The acid contributes to demineralization of the exterior tooth enamel, which accelerates after the pH drops below a critical value () for extended time periods resulting in the need for restorative procedures. Preventative techniques to alert the dentist and caries-susceptible patients regarding vulnerability to dental decay require a clinical measure of plaque activity. Therefore, there is a need to evaluate the acid production capability of plaque deposits in the pits and fissures of occlusal and interproximal regions. A ratiometric fluorescence pH-sensing device has been developed using an FDA-approved dye and LED excitation. Fluorescein spectral profiles were collected using a spectrometer and analyzed with a spectral unmixing algorithm for calibration over the pH range of 4.5 to 7. An in vivo pilot study on human subjects was performed using a sucrose rinse to accelerate bacterial metabolism and to measure the time-dependent drop in pH. The optical system is relatively immune to confounding factors such as photobleaching, dye concentration, and variation in excitation intensity associated with earlier dye-based pH measurement techniques.

In vitro marginal and internal adaptation of metal-ceramic crowns with cobalt-chrome and titanium framework fabricated with CAD/CAM and casting technique.

The purpose of this study was to compare the marginal and internal fit of Co-Cr and titanium ceramic crowns fabricated with 2 different techniques: CAD/CAM milling and traditional casting (TC). Ten traditional casting of Co-Cr (TCC), 10 CAD/CAM milling of Co-Cr (MC), 10 traditional casting of titanium (TCT), 10 CAD/CAM milling of titanium ceramic crowns (MT) were fabricated. Silicone replicas were obtained to measure internal gap volume, marginal gap and internal adaptation that was evaluated at 3 regions: axial wall, axio-occlusal angle, and occlusal surface. Measurements were made with a X-ray micro computerized tomography (micro-CT) and analyzed with Bonferroni and Dunnet T3 post-hoc tests (α = 0.05). One-way ANOVA revealed no statistically significant differences among the groups for measurements at the marginal gap (P > 0.05). At axial wall region the mean values of TCT group were higher than those of groups but only statistically not significant for TCC group (P < 0.05). TCC group statistically gives better results than MC group in axio-occlusal and occlusal regions (P < 0.05). The mean measurement of internal gap volume were 20.59 ± 0.83 mm3 for TCC, 22.73 ± 0.82 mm3 for MC, 22.83 ± 1.11 mm3 for TCT and 20.51 ± 1.16 mm3 for MT. Mean internal gap volume values MT group were smaller than those of groups but only statistically not significant for TCC group (P > 0.05). All groups performed similar marginal adaptation. The cement film thickness at axio-occlusal angle point and occlusal region were higher for MC crowns.

Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: Marginal and internal fit

Statement of problemTrials comparing the overall performances of digital and conventional workflows in restorative dentistry are lacking. PurposeThe purpose of the third part of this clinical study was to test whether the fit of zirconia 3-unit frameworks for fixed partial dentures fabricated with fully digital workflows differed from that of metal frameworks fabricated with the conventional workflow. Material and methodsIn each of 10 participants, 4 fixed-partial-denture frameworks were fabricated for the same abutment teeth according to a randomly generated sequence. Digital workflows were applied for the fabrication of 3 zirconia frameworks with Lava, iTero, and Cerec infiniDent systems. The conventional workflow included a polyether impression, manual waxing, the lost-wax technique, and the casting of a metal framework. The discrepancies between the frameworks and the abutment teeth were registered using the replica technique with polyvinyl siloxane. The dimensions of the marginal discrepancy (Discrepancymarginal) and the internal discrepancy in 4 different regions of interest (Discrepancyshoulder, Discrepancyaxial, Discrepancycusp, and Discrepancyocclusal) were assessed using a light microscope. Post hoc t tests with Bonferroni correction were applied to detect differences (α=.05). ResultsDiscrepancyshoulder was 96.1 ±61.7 μm for the iTero, 106.9 ±96.0 μm for the Lava, 112.2 ±76.7 μm for the Cerec infiniDent, and 126.5 ±91.0 μm for the conventional workflow. The difference between the iTero and the conventional workflow was statistically significant (P=.029). Discrepancyocclusal was 153.5 ±66.8 μm for the iTero, 203.3 ±127.9 μm for the Lava, 179.7 ±63.1 μm for the Cerec infiniDent, and 148.8 ±66.8 μm for the conventional workflow. Discrepancyocclusal was significantly lower for the conventional workflow than for the Lava and the Cerec infindent workflows (P<.01). The iTero resulted in significantly lower values of Discrepancyocclusal than the Lava and the Cerec infiniDent workflows (P<.01). ConclusionsIn terms of framework fit in the region of the shoulder, digitally fabricated zirconia 3-unit frameworks presented similar or better fit than the conventionally fabricated metal frameworks. In the occlusal regions, the conventionally fabricated metal frameworks achieved a more favorable fit than the CAD-CAM zirconia frameworks.

Inflammatory Follicular Cyst in the Maxilla: a Case Report

This study aimed to present the diagnosis of an inflammatory follicular cyst that affected an 18-year-old female patient with leukoderma. She sought dental care for pain in the right anterior region of the maxilla. Clinically, the presence of element 53 and absence of 13 were observed. The panoramic radiograph showed an extensive radiolucent lesion delimited in the apical region of 53 and in the occlusal region of element 13 that was shown to be unerupted with the root in the maxillary sinus. The cytology of aspiration puncture revealed a cystic lesion of odontogenic nature, followed by cystic decompression, exodontia of 53, and the incisional biopsy confirmed the diagnosis of inflammatory follicular cyst. After cystic decompression, an orthodontic button with an orthodontic stainless steel CrNi ligature wire spool of 0.25 mm, for traction of the canine, was installed. The patient underwent orthodontic treatment and followed up for the next 6 months.

Effect of different impression methods and ceramic materials on adaptation of inlays

Objective: The aim of this study was to evaluate the internal and marginal adaptation of inlays fabricated from different types of impressions (conventional and digital) and different ceramics (feldspathic and lithium disilicate). Material and Methods: Forty premolars were prepared for all-ceramic inlay restoration and assigned to 4 groups (n=10), according to the impression method (conventional with addition silicone and digital impressions) and ceramic type (lithium disilicate and feldspathic ceramic blocks). For each type of impression, 10 inlays were fabricated from lithium disilicate blocks and the other 10 from feldspathic ceramic blocks, by means of the CAD-CAM system. The internal adaptation was analyzed by replica. The marginal fit was analyzed under a stereomicroscope by directly measuring the gap formed between the inlay and the tooth in the proximal and occlusal regions. Results: The marginal or internal adaptations were not affected by type of impression (conventional = digital impression), irrespective of the ceramic type. Only the internal adaptation was affected by material, i.e., feldspathic ceramic had lower values than disilicate ceramic, when considering the digital impression. Conclusion: The conventional and digital impressions promote similar marginal and internal adaptation of tested feldspathic and disilicate ceramic inlays. For digital impression the feldspathic ceramic showed better internal adaptation than lithium disilicate. KeywordsCeramics; Dental internal adaptation; Dental marginal adaptation; Dental impression technique.

Characterization of Residual Stresses in Veneering Ceramics for Prostheses with Zirconia Framework.

The aim of this study was to evaluate the influence of the coefficient of thermal expansion (CTE or α) and glass transition temperature (Tg) of three veneering ceramics used with zirconia frameworks of full-arch fixed prostheses. The generation of residual stresses and linear contraction after the simulation of the cooling process and mechanical loading were measured. The analysis was based on the finite element method in three-dimensional model of a maxillary full-arch fixed prosthesis with zirconia framework (e.max ZirCAD) and veneer by felsdpathic ceramics (GEC - IPS e.max Ceram, GVM - Vita VM9 and GLC - Lava Ceram). The linear contraction simulation was performed by cooling the structures from the Tg of each veneer ceramic at room temperature (25°C). A loading of 100 N on the occlusal region of the first molar was performed. The magnitude of the maximum principal stress (smax) and linear contraction were evaluated. The levels of CTE mismatch between veneering ceramics and framework showed no relevant influence on smax and linear contraction. The Tg values of the veneer ceramic showed to be directly proportional to amount of smax and linear contraction. The GEC presented the highest values of smax and linear contraction. The GVM and GLC did not present significant differences between them. In conclusion, GVM was similar to GLC, while GEC presented differences in relation to other veneer ceramics in terms of residual stress and linear contraction.

Do ozone and boric acid affect microleakage in class V composite restorations?

ABSTRACTThe aim of this in vitro study was to evaluate the effects of chlorhexidine gluconate (2%), sodium hypochloride (2.5%), ozone gas, and boric acid at different concentrations (1%, 3%, 5%, and 7%) on microleakage from composite restorations.In a total of 80 extracted human canine teeth, a class V cavity was opened on the buccal surface and the samples were separated into eight groups. In the control group, no procedure was applied for cavity disinfection, then composite restoration (Z250, 3M) was made using single-stage, self-etch adhesive (Single Bond 3M). In the other groups, seven different disinfectants were used, then the cavity was restored. The teeth were split into two in the buccolingual direction, parallel to the long axes. Stain penetration was examined under stereomicroscope and scored. Examination with SEM was made on one sample from each group, selected at random. Statistical evaluations were made using Dunnett C Post Hoc Comparison and Kruskal–Wallis H tests.In the occlusal region evaluation, the groups with the lowest level of leakage were the 3% and 5% boric acid groups, and the highest levels of microleakage were determined in the chlorhexidine group and the 1% boric acid group. In the gingival region, the lowest level of microleakage was in the 5% boric acid group and the highest levels were determined in the 1% and 7% boric acid groups.Boric acid disinfectants used at suitable concentrations were not seen to create a risk in respect of microleakage.

Marginal and internal fit of pre-sintered Co-Cr and zirconia 3-unit fixed dental prostheses as measured using microcomputed tomography

Statement of problemLimited information is available on the precision of new metal processing technologies. PurposeThe purpose of this in vitro study was to evaluate the marginal and internal fit of pre-sintered cobalt-chromium (Co-Cr) and zirconia 3-unit fixed dental prostheses using x-ray microcomputed tomography. Material and methodsThree-unit fixed dental prostheses were prepared on metal dies (N=12) using a typodont model from the maxillary first premolar to the first molar. A standardized preparation with a 1.2-mm chamfer (360 degrees) and a 2-mm occlusal reduction was prepared on abutment teeth. The dies were scanned and divided into 2 groups to receive the fixed dental prostheses (n=6) made of pre-sintered Co-Cr and pre-sintered zirconia. Each framework was seated on its cast, and marginal and internal discrepancies were measured at 9 points, starting from the most distal point from the pontic for the maxillary first premolar and the first molar (points 1-4, mesial; point 5, occlusal; points 6-9, distal) of each abutment tooth using microcomputed tomography. The data were analyzed using the Levene test, t test, and ANOVA (α=.05). ResultsWhen overall mean discrepancy values were compared, no significant difference was observed between pre-sintered Co-Cr and pre-sintered zirconia (P=.085). Discrepancy values for points 1, 2, and 3 were significantly different for pre-sintered Co-Cr and pre-sintered zirconia, with the lowest mean values for point 1 and the highest for point 5. On the abutment tooth basis, for the maxillary first premolar and the first molar, a significant difference was found only in points 6 (P<.001) and 8 (P<.003) for both materials. When the discrepancies for the maxillary first premolar were considered for pre-sintered Co-Cr and pre-sintered zirconia, the mean values were significantly different only at points 1 (P<.001), 2 (P=.007), and 3 (P=.003) and were smaller for pre-sintered zirconia. For the tooth the first molar, a significant difference was observed at point 2 (P=.002) and point 3 (P=.008) for both materials, where the mean values were higher for pre-sintered Co-Cr than for pre-sintered zirconia. The pairwise comparison between points showed a significant difference between measurement points within each material (P<.05). The increase in values between points 1 and 5 was evident for both pre-sintered Co-Cr and pre-sintered zirconia materials. ConclusionsThree-unit fixed dental prostheses made of pre-sintered Co-Cr or zirconia showed similar marginal and internal discrepancy values, with the highest discrepancy values at the occlusal region in both the first premolar and first molar.

In vitro Evaluation and Comparison of Microleakage of Two Restorative Composite Resins in Class II Situations using Confocal Laser Scanning Microscopy

The placement of composite in teeth is not an easy task and it poses many challenges. Microleakage is one of the factors that affects the success of any composite restoration. It influences the longevity of dental restorations. The present study was aimed to evaluate and compare microleakage of two restorative composites resins in class II cavities using confocal laser scanning microscopy (CLSM). This was an in vitro study, which included 20 permanent mandibular first molar. On each tooth, 40 class II cavities were prepared with a carbide bur. The teeth were then randomly divided into two groups of 10 each. Group I included teeth in which SonicFill Bulk Fill composite was used. Group II included teeth in which Tetric EvoCeram Bulk Fill composite was used. The microleakage was measured using confocal microscopy at 10* magnification in the fluorescent mode by a scoring system. Estimation was done at cervical and occlusal levels, wherein group I included 10 teeth which were restored with SonicFill Bulk Fill composite and group II included 10 teeth which were restored with Tetric EvoCeram Bulk Fill composite. Microleakage was quantified on scoring basis, which was consecutively based on the dye penetration at different levels. Data thus obtained statistically revealed that microleakage was comparatively more in group II as compared with group I. In addition, it was somewhat similar on both cervical as well as occlusal regions. The difference was significant (p = 0.05). Comparison was also done at cervical and occlusal levels using Wilcoxon signed-rank test, which showed significant levels of differences (p > 0.05). There is more microleakage in Tetric EvoCeram Bulk Fill composite as compared with SonicFill Bulk Fill composite. No material seems to totally eliminate microleakage in class II situations with gingival margin ended in dentine. However, CLSM is a useful tool in microleakage evaluation that could be used successfully to estimate the severity of microbial penetrations and material of choice as well.

In vitro evaluation of microleakage under orthodontic brackets bonded with different adhesive systems.

Objective:Adhesives systems have a drawback when utilized for bonding orthodontic brackets: they shrink during photopolymerization creating microleakage. The aim of this study was to assess the stability of different orthodontic adhesives around brackets and enamel.Materials and Methods:Sixty noncarious mandibular premolars extracted for orthodontic reasons were randomly divided into six groups of adhesives used for bonding brackets to dental enamel: NeoBond® Light Cure Adhesive Kit, Transbond™ Plus Self-Etching, Victory V-Slot APC PLUS® + Transbond™ MIP, Rely-A-Bond® Kit, Light Cure Orthodontic Adhesive Kit (OptiBond®), and Transbond™ MIP. Following bonding, all teeth underwent 2500 cycles of thermal cycling in baths ranging from 5°C to 55°C before being immersed in 2% methylene blue for 24 h. All samples were examined under a binocular microscope to assess the degree of microleakage at the “bracket-adhesive” and “adhesive-enamel” interfaces in the gingival and occlusal regions of the bracket.Results:A significant difference was found at the “occlusal bracket-adhesive” interface. The highest microleakage values were found in the occlusal region, although no significant. Microleakage was observed in all groups.Conclusion:Group 2 had the highest microleakage values whereas Group 6 had the lowest values.

Investigation of the Er: YAG laser and diamond bur cavity preparation on the marginal microleakage of Class V cavities restored with different flowable composites.

The purpose of this study was to evaluate the efficiency of the Er:YAG laser and diamond bur cavity preparation on the marginal microleakage of Class V cavities. Group 1: bur preparation (bp) + Vertise Flow (VF); Group 2: laser preparation (lp) + VF; Group 3: bp + Adper Easy One (AEO) + Filtek Ultimate Flowable Composite (FUFC); Group 4: lp + AEO + FUFC; Group 5: bp + Clearfil S3 Bond (CSB) + Clearfil Majesty Flow (CMF); Group 6: lp + CSB + CMF. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests (p < .05). More microleakage was observed in cervical regions compared to occlusal regions in all groups (p < .05). No significant difference was observed among all groups in terms of occlusal and cervical surfaces, respectively (p > .05). The use of the Er:YAG laser for cavity preparation with different adhesive systems and flowable composites did not influence microleakage.

Fit of interim crowns fabricated using photopolymer-jetting 3D printing

Statement of problemThe fit of interim crowns fabricated using 3-dimensional (3D) printing is unknown. PurposeThe purpose of this in vitro study was to evaluate the fit of interim crowns fabricated using photopolymer-jetting 3D printing and to compare it with that of milling and compression molding methods. Material and methodsTwelve study models were fabricated by making an impression of a metal master model of the mandibular first molar. On each study model, interim crowns (N=36) were fabricated using compression molding (molding group, n=12), milling (milling group, n=12), and 3D polymer-jetting methods. The crowns were prepared as follows: molding group, overimpression technique; milling group, a 5-axis dental milling machine; and polymer-jetting group using a 3D printer. The fit of interim crowns was evaluated in the proximal, marginal, internal axial, and internal occlusal regions by using the image-superimposition and silicone-replica techniques. The Mann-Whitney U test and Kruskal-Wallis tests were used to compare the results among groups (α=.05). ResultsCompared with the molding group, the milling and polymer-jetting groups showed more accurate results in the proximal and marginal regions (P<.001). In the axial regions, even though the mean discrepancy was smallest in the molding group, the data showed large deviations. In the occlusal region, the polymer-jetting group was the most accurate, and compared with the other groups, the milling group showed larger internal discrepancies (P<.001). ConclusionsPolymer-jet 3D printing significantly enhanced the fit of interim crowns, particularly in the occlusal region.