Enamel Margins Research Articles

Optimizing restorative procedure and material selection for pulpotomized primary molars: Mechanical characterization by 3D finite element analysis

PurposeThis study aimed to assess the stress distribution in pulpotomized primary molars with different types of restorative materials using 3D-finite element analysis (FEA), and provide valuable insights into the selection and application of restorative materials, with the ultimate goal of reducing the risk of pulpotomy failure and protecting residual dental tissue. MethodsFour 3D models of pulpotomized primary molars with different restorative materials according to the material and its elastic modulus were analysed: resin composite, stainless steel crowns (SSCs), prefabricated zirconia crowns and endocrowns. The food layer was also designed before vertical and bucco-lingual forces were applied to simulate physiological masticatory conditions. The results were obtained by colorimetric graphs of the von Mises stresses (VMS) in the restoration and tooth remnant. The maximum shear stress on the bonding interfaces and pressure stress on the Mineral trioxide aggregate (MTA)-pulp interfaces were recorded. ResultsThe results of the 3D-FEA showed that all restorative materials generated stresses and strains on the tooth structure after pulpotomy. In the resin composite group, the marginal enamel exhibited the highest stress peaks. In the zirconia crown and SSC groups, there was a concentration of stress at the dentin-restoration margin. The shear stress concentrations were mainly at the adhesive margins, with lower levels around endocrowns compared to other groups. MTA in the resin composite group experienced more VMS than in the other group. The resin composite group also generated relatively higher pressure stress values at the MTA-pulp interface compared to the other groups. SignificanceIn the model of primary teeth following pulpotomy, the three types of restorations covering the occlusal surface can effectively reduce the stress on pulp capping materials under occlusal loads, thereby potentially decreasing the risk of pulpotomy failure. In addition, the group of endocrowns demonstrated reduced stress at the bonding interface and in the stress concentration zone near the dentist-restoration edge, making them more effective at protecting residual dental tissue.

Materials used for deep margin elevation (Review article)

Abstract: Deep margin elevation (DME) is considered a conservative approach for restoring the deep proximal margin by applying resin composite increments over the preexisting cervical margin to relocate it coronally and facilitate the insertion of indirect restoration. Different materials have been applied in DME. Materials and methods: An analysis of the research publications in the literature dealing with the different restorative materials used for DME regarding their fracture resistance, microleakage, marginal quality, and marginal adaptation that have been published from 2000 until 2023 using MEDLINE (PubMed) and Google Scholar databases. Results. The studies showed that enamel margin had the best gap-free margins, followed by direct bonding to dentine, DME required careful layering of 1 mm increment to show fewer gaps, and there was no significant difference compared with those without margin elevation. DME didn't significantly influence the fracture strength in all of the materials utilized for DME except that elevated with bulk-fill Smart Dentin Replacement. Conclusions: This review included 16 in vitro studies concerning the different restorative materials used for DME. The samples in multiple layers of 1 mm increment of DME showed similar results to those where the indirect restorations bonded directly to dentine. On the other hand, in clinical practice, DME assists in making indirect restoration cementation easier, faster, and more reliable. Therefore, further research and clinical observations are needed.

Adaptability of VisCalor versus bulk-fill composites using scanning electron microscope: an in-vitro study

Purpose To evaluate the marginal integrity of two types of bulk-fill composite resins in Class I box-shaped cavities. Materials and methods Forty extracted human sound molars were selected. The teeth were fixed with sticky wax to the base of plastic cylinder and the cylinder was filled with self-curing acrylic resin so that only root was embedded. Simple Class I box-shaped cavities were prepared using a fissure carbide bur with water spray and finished with fine-grained flame burs. The overall dimensions and depth of the cavities were standardized as follows: 4 mm length mesiodistally and 3 mm width buccolingually and up to 4 mm depth. All prepared cavities were bonded using Futurabond M+ one-step self-etch adhesive system. The teeth were randomly divided into two groups (n = 20 teeth each): group I: specimens were restored with VisCalor composite bulk-fill composite resin, which is heated before insertion using a VisCalor dispenser dental device. Group II: specimens were directly restored with X-tra fill bulk-fill composite resin without preheating. After curing, finishing and polishing were performed. Each group was subdivided into two subgroups a and b (n = 10) according to whether subjecting 500 thermocycling fluctuations or not. Each specimen was sectioned buccolingually through the center of the composite resin restoration in two halves, and then cleaned under running tap water and subjected to thorough ultrasonic cleaning to get rid of both soft and hard surface deposits. All sectional samples were fixated in cylindrical carriers, and a thin layer of gold was applied to the surfaces. The marginal adaptation of composite restorations and ultramorphology of adhesive bonds were analyzed at ×50, ×1000 magnification, with a scanning electron microscope. ×50 magnification was utilized to measure the length of margins free gap in enamel and dentin by Autodesk Auto CAD program and expressed in mm/percent. All data of measurements of the length of nongaped margins in enamel and dentin are collected, tabulated, and statistically analyzed. Results Group Ia (VisCalor bulk-fill not thermocycled), recorded the highest mean value of marginal free-gap with 10.26 ± 0.27 mm (93.31%), while group IIb (X-tra-fill bulk-fill thermocycled) recorded the lowest mean value in 7.90 ± 0.26 mm (73.04%) and the difference was statistically highly significant (P = 0.000). In general, group I recorded higher mean values of marginal free gap and adaptation in mm/percent than group II, and the difference was statistically highly significant at P value of 0.000 (9.86 ± 0.55 and 8.23 ± 0.39 mm and 89.15 ± 5.38 and 74.89 ± 3.69%, respectively). Bulk-fill restorations without thermocycling exhibited a higher mean value of marginal free gap and adaptation in mm/percent than the thermocycled one with a significant difference recorded at P value of 0.005. Conclusion Using preheated VisCalor bulk-fill composites could decrease the marginal gap formation improving the continuity at the tooth–restorative material interface than conventional bulk-fill restorations. On the other hand, thermocycling.

Over-eruption in marsupial carnivore teeth: compensation for a constraint

Pronounced over-eruption of the canine teeth, causing the cervical enamel margin to extend beyond the alveolar bone and exposing the root, occurs with age and growth in Australian marsupial carnivores, much more than in eco-morphologically equivalent placental carnivores. Suppression of functional tooth replacement is characteristic of marsupials, where most placentals have the primitive diphyodont pattern of two generations of incisor, canine and premolar teeth. Canine and molar tooth dimensions of four species of marsupial carnivores (thylacine Thylacinus cynocephalus , Tasmanian devil Sarcophilus harrisii and two quolls Dasyurus spp . ) and canine dimensions of seven eco-morphologically equivalent placental carnivore species were measured from museum specimens. Canine dimensions were measured in a time series on live wild-living individual devils and quolls. The canine teeth and to a lesser extent the molar teeth of marsupial carnivores continue to erupt through life, resulting in a net increase in tooth height and diameter, a phenomenon not evident in placental carnivores. Potential mechanisms causing over-eruption include tooth wear and gradual release of occlusal pressure as the individual grows. Over-eruption in marsupial carnivores may be a compensatory response for tooth size limits imposed by monophyodont tooth replacement, ensuring that animal's teeth are scaled to jaw size from juvenile to adulthood.

The Influence of Adhesive Strategy, Type of Dental Composite, and Polishing Time on Marginal Gap Formation in Class I-like Cavities

Even after more than six decades of dental composite invention (1962), there is still controversial information about the time in which composite restorations should be polished in order to avoid marginal gap formation at the tooth–composite interface. The aim of the present study was to analyze the influence of adhesive strategy, the type of dental composite, and polishing time on marginal gap formation (%MG) at the tooth–composite interface. Class I-like cavities were hybridized with a universal adhesive system (Single Bond Universal) through two strategies: selective enamel etching (SEE) or self-etching mode (SEM). Cavities were filled with two types of dental composites: nanofilled (Z350) or bulk fill (Filtek One Bulk Fill—ONE), and polishing was performed immediately or delayed for 7 days (n = 5). %MG was evaluated by using a 3D laser confocal microscope. As flexural modulus (FM) and degree of conversion (DC%) are determinants of marginal integrity in dental composite restorations, these properties were evaluated for both composites. Data were analyzed by ANOVA and Tukey’s HSD test (α = 0.05). Cavities hybridized following the SEE strategy presented lower %MG (p < 0.05). Z350 showed higher %MG than ONE (p < 0.05). There was no difference in %MG between the polishing times when the SEE strategy was used (p > 0.05). Z350 presented higher FM than ONE (p < 0.05). DC% was found to be not significant (p > 0.05). The results suggest that selective enamel etching (SEE) is a better strategy for producing less %MG in composite restorations with enamel margins irrespective of the time in which the restoration is polished.

Marginal Adaptation of In Vitro Class II Restorations Made Out of Bulk or Conventional Composite Using Single- or Multi-Layered Techniques.

Objective: Testing the influence of various restorative materials (conventional or bulkfill composites) and filling techniques (single- or multi-layered techniques) on the in vitro marginal adaptation of large class II direct composites with supra and sub-gingival margins subjected to thermomechanical loading (TML). Methods: A total of 40 prepared teeth were attributed randomly to five experimental groups. In Group 1, restorations were made of multi-layered high-viscosity conventional composite (Tetric EvoCeram); in Groups 2 and 3, restorations were made of a high viscosity bulkfill composite (Tetric EvoCeram Bulk Fill) applied in one (Group 2) or three layers (Group 3); in Groups 4 and 5, restorations were made of a flowable bulkfill composite (SDR flow) applied in one (Group 4) or two layers (Group 5), covered with a layer of high-viscosity conventional composite (Ceram-X Universal). A single adhesive (OptiBond FL) was used in all groups. All specimens were submitted to a staged TML comprising three phases (2 × 500,000 and 1,000,000 cycles) at 50 N with 3350 thermal cycles (5 to 55 °C) every 500,000 cycles. The tooth-restoration interfaces on proximal surfaces were evaluated quantitatively by scanning electron microscopy, before and after each TML phase, hence at three timepoints (T0, T1, T2 and T3). The following segments were considered for evaluation: proximal, vertical enamel margins (assessed individually on both restoration sides), cervical enamel (restoration side above CEJ) and cervical dentin margin (restoration side below the CEJ). Results: TML induced a significant reduction in continuous adaptation at both enamel and dentin margins in all groups, with percentages of continuous margins ranging from 75.2 to 91.8% at T0, and decreasing to values ranging from 21.3 to 73.9% at T3. Both composite systems and layering protocols had a significant influence on marginal adaptation of the restorations, with statistical associations depending on the restoration group and the timepoint considered. Defective margins in enamel were all of a cohesive nature with micro-fractures, while in dentin, interfacial gaps were the main defect observed. Conclusions/Clinical significance: The present results highlighted significant degradation of marginal adaption after long-term in vitro fatigue test using materials even with high-viscosity conventional resin composites, applied with a proper layering approach in medium-large sub-gingival cavities. While no significant differences were observed at the dentin cervical margins, there was a tendency for better adaptation at the enamel margin when using a higher modulus material with a multi-layered technique.

Evaluation of Effect of Vitamin C on Streptococcus Mutans Induced Secondary Caries: An In vitro Study

This study aimed to assess and understand the protective effect of vitamin C against secondary caries formation around the margins of class V restorations with the help ofan in-vitro bacterial caries model. In this study, a total of 30 mandibular premolars were chosen and assigned to three groups (n=10). In this study, Class V composite restorations were prepared and along with pretreatment of the cavity walls with various solutions like Vitamin C (ascorbic acid solution), HEPES buffer solution and chlorhexidinedigluconate. After incubating specimens with Streptococcus mutans, dentin and enamel were assessed using Fluorescence Microscopy.The study showed Vitamin C (Ascorbic acid) inhibited the formation of secondary caries near the dentin resin interface. No inhibitory effects were observed in enamel margins. From the study, it could be concluded that the incorporation of ascorbic acid in the restorative procedure of resin composite may inhibit secondary caries formation. Neither the application of chlorhexidine nor HEPES buffer had much effect on the inhibitory effect on secondary caries.

In vitro microleakage at the enamel and dentin margins of class II cavities of primary molars restored with a bulk-fill and a conventional composite.

This study assessed the enamel and dentin margin microleakage of class II cavities of primary molars restored with a bulk-fill and a conventional composite. In this in vitro, experimental study, standard class II cavities were created in the proximal surfaces of 60 extracted primary molars. The teeth were randomly divided into two groups, and restored with SonicFill bulk-fill and Filtek Z250 conventional composite along with Single Bond 2 adhesive. The teeth were coated with two layers of nail varnish to 1 mm around the restoration margins, and the apices were sealed with wax. The teeth underwent 1500 thermal cycles and incubated at 37°C for 24 h. They were then immersed in 1 M silver nitrate in the dark, rinsed with water, immersed in developing solution for 12 h, and exposed to fluorescent light. Next, they were mesiodistally sectioned, and digitally photographed under a stereomicroscope at ×10 magnification. The dye penetration depth was measured by a blind observer, and analyzed by the Mann-Whitney U test (α = .05). No significant difference existed in microleakage between the two composite groups at the enamel (p = .76) or dentin (p = .16) margins. In both composite groups, microleakage at the dentin margins was significantly greater than that at the enamel margins (p = .000). Considering the absence of a significant difference in microleakage, SonicFill bulk-fill composite can be used as an alternative to Filtek Z250 conventional composite for restoration of primary molars to benefit from its advantages such as simpler and faster application.

FEATURES OF THE CERVICAL AREA STRUCTURE OF PERMANENT TEETH OF DIFFERENT GROUPS

According to the findings of various authors, almost 100% of the world's population suffers from dental caries. Carious lesions of the cervical area of the teeth attract special attention since their localization does not provide for the early detection of the pathological process, and the features of the microbiocenosis of the oral cavity and the structural features of the enamel-cementum-dentine junction are significant risk factors for the development and progression of cervical caries. The aim of the study is to research different options of the cervical area structure of teeth of different groups and to find out the frequency of their occurrence. Material and methods. We determined the ratio of the hard tissues – enamel, cementum and dentin – in the cervical area of 320 permanent teeth of the maxilla and mandible (10 teeth each of 11-18, 21-28, 31-38 and 41-48), which were removed due to clinical indications in their vestibular, oral (palatal/lingual), medial and distal contact surfaces. Results. Four options of the hard tissue ratio in the cervical region of the tooth were identified: lack of contact between enamel and cementum and the presence of zones of open dentin; contact of the enamel margin with the cementum; enamel overlapping cementum; cementum overlapping enamel. Each of the specified options occurs with different frequency on the vestibular, oral, medial and distal contact surfaces of teeth of different groups. Among all examined tooth surfaces, 2% have a zone of exposed dentin in the cervical area, 4% have the enamel in the cervical area covered with a layer of cementum, 47% of the surfaces have variants of contact of enamel margin with cementum and overlapping of cementum with a layer of enamel. Further study of the characteristics of the ratio of the hard tissues of the tooth in the cervical area will allow to find out the etiological factors of the development of cervical lesions and offer new and improved methods of their prevention, diagnosis and treatment.

Microleakage and Marginal Integrity of Surface-Coated and Laser-Pretreated Class V Composite Restorations in Primary Teeth.

Introduction: Despite the advanced formulations of resin composites, microleakage is still among the commonest causes of clinical failure of these restorations. We evaluated the effect of surface coating and laser pretreatment on the microleakage of Class V resin composite restorations in primary teeth. Methods: Sixty extracted primary molar teeth having intact lingual or facial surfaces were randomly allocated into the control, G-Coat Plus surface coating, and erbium-doped yttrium aluminum garnet (Er:YAG) laser pretreatment groups. Class V cavities were provided with the coronal and gingival margins in the dentin and enamel, respectively. Restoration of the cavities was done with Z250 resin composite and they were thermocycled, followed by immersing in 2% basic Fuchsin dye for 24 hrs. Samples underwent sectioning occlusogingivally and the microleakage was assessed under a stereomicroscope (40×). Statistical analysis was done via SPSS and Kruskal-Wallis test (α=0.05). Results: The control and G-Coat plus groups were significantly different regarding the microleakage (P<0.001), and G-Coat Plus and laser pretreatment groups (P<0.001) at both gingival and occlusal margins. However, it showed no significant difference between the laser and the control group on the enamel (P=0.063) and dentin margins (P=0.757). Microleakage at the gingival margins was significantly greater compared to the occlusal margins in the control and laser groups (P<0.001), but not in the G-Coat Plus group (P=0.051). Conclusion: G-Coat plus coating significantly reduced microleakage at dentin and enamel margins of Class V composite restorations in primary teeth, in comparison with other groups of the study. Also, dentin margins showed more significant amounts of microleakage versus enamel margins in all groups, except for the G-Coat Plus group.

The effect of the material used and the pulp chamber extension depth on stress distribution of endocrowns: A three-dimensional finite element analysis

Aim: The aim of this study was to examine the effects of materials used and the depth of extension into the pulp chamber on stress distribution in mandibular molar endodontically treated teeth with endocrown restoration using three-dimensional (3D) finite element analysis (FEA). Methodology: Three-dimensional finite element analysis models were obtained at two different pulp chamber extension depths by taking a tomography of a root canal-treated mandibular molar tooth extracted for periodontal reasons: 2.5 mm (Model A) and 3.5 mm (Model B). Models were divided into the following three groups according to material type used: Vita Enamic (VE), Lava Ultimate (LU), and IPS e.max CAD (EMX). The aforementioned model groups were further divided into the following two subgroups according to the types of cement used: NX3 and MaxCem Elite Chroma (MX). Maximum principal stress (MPa) values under 600 N vertical load were investigated to evaluate the effect of restoration design, material type, and cements used on stress distribution. Results: The maximum stress on the restoration was observed in the EMX material type (13.000 MPa) in the MX cement group in Model A, while the lowest was observed in the LU material (5.932 MPa) in the NX3 cement group in Model A. The areas of highest stress for both Models A and B were observed in the restoration areas corresponding to the enamel margins. Conclusion: Materials with a higher elastic modulus show a higher stress area on the restoration surface, while the stress values they transmit are lower. Materials with the elastic modulus close to dentin have more homogeneous stress distributions within the restoration. How to cite this article: Güntekin N, Mohammadi R, Tunçdemir MT. The effect of the material used and the pulp chamber extension depth on stress distribution of endocrowns: A three-dimensional finite element analysis. Int Dent Res 2022;12(Suppl.1):1-9. https://doi.org/10.5577/intdentres.436 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Riboflavin (Vitamin B2), Turmeric (Curcumin) Photosensitizers Mediated Photodynamic Therapy, and Er, Cr: YSGG on Microleakage of Class V Cavities Restored by Resin-Modified Glass-Ionomer Cement

Purpose: The present study aimed to assess the effect of RF and CP intervened PDT and Er, Cr: YSGG laser on microleakage in class V RMGIC restorations in permanent teeth. Materials and Methods: In-vitro eighty standardized class V cavities (4×4×2) were prepared in extracted permanent molars based on ICDAS II (International Caries Detection and Assessment System II) caries severity code 0. All samples were arbitrarily alienated into four groups: Group 1, PDT mediated riboflavin photosensitizer (RF) [concentration of 150 μg/mL]; Group 2, PDT with curcumin photosensitizer (CP) [concentration of 100 μg/mL]; Group 3, Er, Cr: YSGG laser application; Group 4, control group: rinsed and dried dentin. Cavities were restored with conventional RMGIC. The specimens were immersed in 0.5% Fuchsine solution for 24 hrs. and sectioned. Microleakage scores were assessed under a microscope. Intergroup and intragroup comparisons were made at enamel and cementum margin respectively. Data were analyzed by non-parametric Kruskal-Wallis test and Wilcoxon tests at the level of significance deemed p &lt; 0.05. Results: Riboflavin and curcuminmediated PDT would produce a superior reduction (95% viz 90%) of microleakage as compared to Er, Cr: YSGG laser (85%), and no control groups. Cu-PDT observed the highest amount of microleakage with the least amount of microleakage in the control group. Conclusion: Riboflavin and curcumin photosensitizers mediated PDT and Er, Cr: YSGG laser has the potential to be utilized in class V cavities before RMGIC restorations at enamel margins without adversely affecting the marginal integrity.

Development and Assessment of Bioactive Coatings for the Prevention of Recurrent Caries Around Resin Composite Restorations.

To develop hydrophilic resin-based surface coatings containing bioactive agents (proanthocyanidins from Vitis vinifera and calcium silicate) and assess their protective role at the dentin and enamel margins of cervical restorations against demineralization under simulated conditions of high and low caries activity. Suboptimal resin composite restorations were placed on cervical cavity preparations on buccal and lingual surfaces of thirty-two molars after a contamination protocol. Groups were divided according to the resin-based coatings (n=8): resin without bioactive (C), resin containing 2% enriched Vitis Vinifera (VVE), and resin coat containing 10% calcium silicate (CaSi). The control group did not receive a resin (NC). To simulate a hydrolyticenzymatic degradation, specimens were subjected to 2-month storage followed by incubation in esterase at 37°C for 8 days. Afterwards, recurrent caries was induced using a pH-proteolytic model on half of the specimens to simulate high caries activity, and the other half remained in simulated body fluid (SBF). Measurements of cross-section microhardness (KHN) and infiltration with rhodamine-B assessed the micropermeability (MP), the extent of demineralization (ED), and the demineralization area (DA). Data were analyzed using analysis of variance (ANOVA) and post-hoc tests (α=0.05). VVE and CaSi presented higher cross-sectional KHN values for enamel and dentin (p<0.001). The bioactive coatings resulted in lower MP, ED, and DA compared to NC (p<0.005) in enamel and dentin. CaSi coating preserved the enamel from demineralization (p=0.160). The application of bioactive coatings represents a potential strategy to protect the enamel-dentin margins of resin restorations.

Influence of Matrix Type on Marginal Gap Formation of Deep Class II Bulk-Fill Composite Restorations.

Background: To test the hypothesis that transparent matrices result in more continuous margins of bulk-fill composite (BFC) restorations than metal matrices. Methods: Forty standardized MOD cavities in human molars with cervical margins in enamel and dentin were created and randomly assigned to four restorative treatment protocols: conventional nanohybrid composite (NANO) restoration (Tetric EvoCeram, Ivoclar Vivadent, Schaan, Liechtenstein) with a metal matrix (NANO-METAL) versus transparent matrix (NANO-TRANS), and bulk-fill composite restoration (Tetric EvoCeram Bulk Fill, Ivoclar Vivadent, Schaan, Liechtenstein) with a metal matrix (BFC-METAL) versus transparent matrix (BFC-TRANS). After artificial aging (2500 thermal cycles), marginal quality was evaluated by scanning electron microscopy using the replica technique. Statistical analyses were performed using the Mann–Whitney U-test and Wilcoxon test. The level of significance was p < 0.05. Results: Metal matrices yielded significantly (p = 0.0011) more continuous margins (46.211%) than transparent matrices (27.073%). Differences in continuous margins between NANO (34.482%) and BFC (38.802%) were not significant (p = 0.56). Matrix type did not influence marginal gap formation in BFC (p = 0.27) but did in NANO restorations (p = 0.001). Conclusion: Metal matrices positively influence the marginal quality of class II composite restorations, especially in deep cavity areas. The bulk-fill composite seems to be less sensitive to the influence of factors such as light polymerization and matrix type.

Evaluation of marginal adaptation of two different composite

This study aimed to investigate evaluation of marginal adaptation of two different bulk fill composites. 10 freshly extracted teeth were divided into two groups of 5 teeth each. Class v cavity was prepared in the CEJ of maxillary first premolars. Restored with sdr flow+ and coltene fill up.Artificial aging was done with thermocycling machine done and samples were immersed in methylene blue solution for 24 hours.samples were sectioned in center of the restoration and viewed under stereomicroscope. Data were subjected to the NPar test and mann-whitney test (a=0.05). Overall result showed both bulk fill composites showed significant leakage after evaluating with stereomicroscope. It was found that there is no statistically significant difference between the two groups. Bulk fill flowable resins provided significantly better marginal seal in dentin,both before and after artificial aging. Both bulk fill flowable resins showed similar microleakage values at enamel margins.

Mechanical Behavior of Alkasite Posterior Restorations in Comparison to Polymeric Materials: A 3D-FEA Study.

The present investigation evaluated the effect of the combination of different dental filling materials in Class I cavities under occlusal loading using three-dimensional finite elements analysis (FEA). Six computer-generated and restored models of a lower molar were created in the CAD software and compared according to the biomechanical response during chewing load condition. Two adhesively bonded bulk restorative materials [bulk-fill resin composite (BF) or Alkasite (Alk)] were evaluated with or without the presence of a base material below (flowable resin composite or glass ionomer cement). A food bolus was placed on the occlusal surface mimicking the compressive occlusal load (600 N) during the static linear analysis. The maximum principal stress (tensile) was calculated as stress criteria in enamel, dentin and restoration. All models showed high stresses along the enamel/restoration margin with a similar stress trend for models restored with the same upper-layer material. Stress values up to 12.04 MPa (Alk) or up to 11.12 MPa (BF) were recorded at the enamel margins. The use of flexible polymeric or ionic base material in combination with bulk-fill resin composite or Alk did not reduce the stress magnitude in dentine and enamel. Class I cavities adhesively restored with bulk-fill resin composite showed lighter stress concentration as well as Alk. Therefore, adhesively bonded Alk restoration showed a promising mechanical behavior when used with different base materials or as a bulk restoration for posterior Class I cavity.

A Radio-Odontometric Analysis of Sexual Dimorphism in First Molars Using Cone-Beam Computed Tomography.

Different techniques for sex prediction are developed and used in the forensic medicine field. One of these methods is based on the teeth morphometry. The aim of the present study was to evaluate the degree of sex determination of the maxillary and mandibular first molar teeth in cone beam computed tomography images. This study was carried out on cone beam computed tomography images of 100 men and 100 women with a mean age of 21.28 ± 2.47 years. The roof, floor and height of pulp chamber, as well as marginal enamel thickness and dentin thickness at the height of contour, tooth width, and crown length were measured. Student t test and discriminant analysis were applied to assess the differences in the measured parameters between men and women. According to the present study, the maxillary first molar was more dimorphic than the mandibular teeth. The accuracy of sex identification of mandibular and maxillary first molar tooth was 84% and 77%, respectively. The mesiodistal measured variables were more accurate in sexual differentiation than the buccolingual ones. For sex differentiation, the most dominant variables for maxillary and mandibular first molar teeth were crown height and dentin thickness, respectively. The first molar tooth showed an acceptable level of sex determination accuracy based on the odontometric measurements.

Minimally Invasive Restoration of Fractured Maxillary Central Incisors with Partial Laminate Veneers- A Case Series

Porcelain laminate veneers are one of the most preferred treatment methods today, due to the increasing interest in minimally invasive approach and their superior aesthetic properties. With the appreciation of the minimally invasive approach and the developing adhesive procedures, the partial laminate veneers have become more popular in dental field. In these case series, the teeth were restored with partial laminate veneers by only intervening in the fractured area. In this case series, the teeth that were restored with partial laminate veneers were prepared with different techniques. Preparation was performed without bevel in enamel margin in the case 1, with incisal overlap and bevel to create more natural transition on tooth surface in the case 2. In the case 3, preparation with incisal overlap was performed with preparation of the palatal surface of the tooth. The optical impression was made with the digital camera of the Chairside Economical Restoration of Esthetic Ceramic (CEREC) acquisition unit (Omnicam CEREC Sirona, Bensheim, Germany), in the first case. In the other cases, impression was taken with elastomeric impression materials. In addition, restorations were fabricated from feldspathic porcelain and lithium disilicate porcelain. In all the cases, restoration was cemented with resin cements. The following cases present the minimally invasive treatment of maxillary central incisors with a partial laminate veneers fabricated from different ceramic materials. New materials, procedures, and techniques provide patients an improved quality of life and a greater self-esteem with creating a confident aesthetic smile.

The Effect of Radiotherapy on the Marginal Adaptation of Class II Direct Resin Composite Restorations: A Micro-computed Tomography Analysis.

This laboratory study was designed to evaluate the marginal adaptation of Class II mesio-occlusodistal (MOD) restorations at the cervical region with micro-computed tomography (micro-CT). Two groups of restorations were compared: 1) those that had been exposed to radiotherapy before restoration was performed using a universal adhesive in etch-and-rinse and self-etch modes; and 2) those that had previously been restored using a universal adhesive in etch-and-rinse and self-etch modes and had subsequently undergone radiotherapy. Sixty intact human molars were randomly divided into groups according to irradiation status: no radiotherapy (control group); radiotherapy followed by restoration (radiotherapy-first group); and restoration followed by radiotherapy (restoration-first group). These three groups were then subdivided into two groups each on the basis of adhesive application type (etch-and-rinse and self-etch modes), for a total of six groups (n=10/group). Standardized Class II MOD cavities were prepared. A universal adhesive (Clearfil Universal Bond Quick, Kuraray, Okayama, Japan) was applied. The teeth were restored with resin composite (Estelite Posterior Quick, Tokuyama, Tokyo, Japan). The radiotherapy protocol was conducted with 60 gray (Gy) at 2 Gy/day, five days a week for six weeks. Adhesive defects were analyzed in distal and mesial views and evaluated with micro-CT (SkyScan 1174v2, Kontich, Antwerp, Belgium) on the basis of the volume of black spaces between the cavity walls and the restorative materials (mm3). The data were analyzed using the Kruskal-Wallis, Mann Whitney U and Wilcoxon tests (p<0.05). The radiotherapy protocol did not affect the marginal adaptation of the universal adhesive at the cervical regions. Regarding the application modes, for the radiotherapy-first group, the self-etch mode caused significantly higher adhesive defects than the etch-and-rinse mode at the dentin margin. For the no-radiotherapy group, the adhesive defects at the dentin margin were significantly higher than at the enamel margin with the application of the etch-and-rinse mode.

Bond Strength and Microleakage of a Novel Glass Ionomer Cement Containing Silver Diamine Fluoride.

Objectives To investigate the shear bond strength and microleakage of glass ionomer cement (GIC) containing silver diamine fluoride (SDF). Materials and Methods Sound human permanent premolars were divided into the following three groups: 1) GIC (Fuji IX), 2) GICSDF-S: GIC + SDF (Saforide), and 3) GICSDF-T: GIC + SDF (Topamine). Shear bond strength ( n = 14/group) was measured using a universal testing machine and compared between groups (one-way ANOVA and Tukey HSD, p < 0.05). Microleakage ( n = 15/group) at enamel and dentin margins was scored using a stereomicroscope (10x) and compared between groups (Chi-square, p < 0.05). Results There were significant differences in shear bond strength between the GIC and GICSDF-S groups and between the GIC and GICSDF-T groups. The GIC group had the lowest shear bond strength among the groups; however, there was no significant difference between the GICSDF-S and GICSDF-T groups. The microleakage test results were not significantly different between groups at the enamel margin or dentin margins. Although the GIC group demonstrated a higher dye penetration score at the enamel and dentin margins, the difference was not significant. Conclusions Within the limitations of this study, we conclude that incorporating SDF into GIC results in higher shear bond strength while not increasing microleakage at the enamel and dentin margins.