Premolars Research Articles

Fracture resistance and fractographic analysis of pressable glass-ceramics with different partial coverage designs for maxillary premolars

BackgroundPartial coverage concepts have met the main goal of conservative dentistry. Vonlays, which combine features of veneers and onlays, are a recent alternative to full coverage designs and overlay partial coverage restorations. This in vitro study was conducted to compare the fracture resistance of the newly introduced pressable zirconia-reinforced lithium silicate with pressable lithium disilicate ceramic and to determine the optimal preparation design for partial coverage on upper premolars.MethodsFifty-two duplicated epoxy resin dies were prepared following vonlay and overlay preparation guidelines. For each preparation (n = 26), the specimens were divided into two subgroups to be restored with lithium disilicate (IPS e.max Press) or zirconia-reinforced lithium silicate (Vita Ambria) (n = 13 each). Ceramic vonlays and overlays were bonded using dual cure resin cement, subjected to thermomechanical fatigue, and the load to fracture was tested by using a universal testing machine. The specimens were fractographically analyzed via scanning electron microscopy (SEM). The normality of the fracture resistance data was checked using the Shapiro‒Wilk test and Q‒Q plots, and two-way ANOVA was used to assess the effect of the type of preparation and ceramic material on the fracture resistance.ResultsThe group of overlays restored with zirconia-reinforced lithium silicate showed the highest mean fracture load (1218.69 N), while the group of vonlays restored with lithium disilicate had the lowest mean fracture resistance (967.15 N). The effect of preparation design and material type on fracture resistance was significant for both factors, p = 0.003 and p < 0.0001, respectively. Different features of the fracture surfaces, such as arrest lines, hackles, and directions of crack propagation, were observed.ConclusionsZirconia-reinforced lithium silicate exhibited greater resistance to fracture compared to lithium disilicate, making it a potential substitute for partial coverage restorations. Additionally, the overlay showed superior fracture resistance when compared to the vonlay preparation design.

Cone-Beam Computed Tomography Study of Root and Canal Morphology of Mandibular First and Second Premolars in Nepalese Population

Cone-Beam Computed Tomography Study of Root and Canal Morphology of Mandibular First and Second Premolars in Nepalese Population

The effect of two preparation designs on the fracture resistance and marginal adaptation of two types of ceramic crowns using CAD/CAM technology (In vitro study)

BackgroundRecently, prosthodontic approaches involve more conservative procedures that include less invasive finish line preparations that use less ceramic thickness.Aim of the studyThis in vitro study aimed to evaluate the effect of vertical preparation and modified vertical preparation designs on the marginal adaptation and fracture resistance of two types of ceramic crowns using CAD/CAM technology.Materials and methodsTwo typodont maxillary first premolars were embedded in acrylic resin. Forty positive replicas of epoxy resin dies were used that were divided into two groups depending on the preparation design (n = 20); Group V (Vertical): dies with feather edge finish line and Group MV (Modified vertical): dies with feather edge finish line, where a reverse shoulder of 1 mm depth was placed on the buccal surface 1.5 mm from the occlusal surface. Each group was further subdivided into two subgroups according to the type of ceramic material (n = 10): Subgroup Va and subgroup MVa for lithium disilicate (e.max CAD) and subgroup Vb and subgroup MVb for zirconia (zolid ht+). Crown restorations were made with CAD-CAM technology. The marginal adaptation was assessed using a stereomicroscope both prior to cementation and after cementation and aging. Fracture resistance was tested with a universal testing machine, and the data were statistically analyzed.ResultsMarginal adaptation showed no significant differences between subgroups before or after cementation and aging. Three-way ANOVA indicated that preparation design (p = 0.516) and material (p = 0.269) had no significant effect, but cementation had a significant effect (p < 0.0001) on the marginal adaptation. According to two-way ANOVA test, Subgroup (MVb) showed the highest result followed by subgroup (Vb) and subgroub (MVa) and the least was subgroub (Va). Fracture modes showed no significant differences among the subgroups (p = 0.982).ConclusionsMarginal adaptation of lithium disilicate and zirconia crowns remained clinically acceptable regardless of preparation design. While the modified vertical preparation with a reverse shoulder notably enhanced the fracture resistance of both materials, with zirconia demonstrating superior fracture resistance compared to lithium disilicate with average values exceeding premolar biting force.

Impact of LASER activated irrigation on the retrievability of Guttaflow bioseal (in-vitro study)

BackgroundThis study aimed to evaluate the efficiency of diode LASER activated irrigation in the removal of GuttaFlow Bioseal root canal filling material during retreatment.Materials and subjectsRoot canals of forty-five single-rooted human mandibular premolar teeth were prepared with ProTaper Universal rotary system and obturated with lateral condensation obturation technique using Gutta Percha and Roeko GuttaFlow Bioseal root canal sealer. All specimens were retreated with ProTaper Universal Retreatment System files then divided to three different groups according to the technique of activation of irrigation. Samples were sectioned, and the residual filling remnants were captured using digital camera attached to microscope. Data was collected by three different interpreters, to eliminate the subjectivity of the process, using the ImageJ Software. The mean value of the data was obtained and evaluated statistically. The significance level was set at P ≤ 0.05.ResultsThe remaining filling materials in the canals irrigated with ultrasonic activation (6.17 ± 1.42 at coronal level, 10.93 ± 1.91at middle level, and 14.58 ± 2.23 at apical level) were less than these irrigated with LASER activation (15.87 ± 3.78 at coronal level, 21.28 ± 4.44 at middle level, and 27.06 ± 2.68 at apical level). Maximum amount of remaining filling materials was present in the canals irrigated with passive side-vented syringe (23.07 ± 3.22 at coronal level, 38.09 ± 7.27 at middle level, and 34.24 ± 9.77 at apical level).ConclusionThe activation of irrigation techniques used were incapable of complete removal of filling material at root canal walls.

A Comparative Ex Vivo Study on Apex Locator Precision in Mature Teeth and Immature Teeth With Divergent Canals.

This study investigates the accuracy of an apex locator in mature andimmature teeth with divergent root canals ex vivo. Fifty extracted premolar teeth were utilized for the study, with 25 mature teeth (Nolla stage 9 or 10) and 25 immature teeth (Nolla stages ≤ 8). The discrepancies between the actual length (AL) and the electronic length (EL), measured using a Bingo 1020 apex locator, were compared and analyzed. Statistical analysis included Pearson's correlation analysis, a T-test for independent samples, and multiple linear regression. Statistical significance was set at p < 0.05. The difference between AL and EL in immature teeth was significantly higher than in mature premolar teeth. Nonetheless, patient gender or jaw type (upper/lower) did not affect the accuracy of electronic apex locator (EAL) measurements. EAL readings are less accurate in immature teeth than in mature teeth. Supplementary measures, such as radiographic length determination and wet-dry paper point tests, are required to confirm theworking length for improved treatment outcomes and patient compliance.

The Efficiency of Different Supplementary Irrigation Techniques After Nickel-Titanium Rotary System in Endodontic Retreatment

Objective: To assess the efficiency of XP-Endo Finisher file (XPFF), EDDY, and diode laser as supplementary irrigation activation techniques following nickel-titanium rotary files in the endodontic retreatment. Methods: 48 mandibular premolars were collected. Each root canal was shaped and filled with EndoSequence BC sealer and gutta percha. After 14 days, endodontic retreatment was performed using D-Race instruments. Then, 48 samples were assigned into 4 groups (n=12) as control, diode laser, EDDY, and XPFF according to the supplementary irrigation methods. After the irrigation procedure, all samples were visualized under a stereomicroscope. The remaining root filling material was scored and compared statistically using Kruskal-Wallis and Post-hoc pairwise comparison tests. Results: In all thirds, there was a significant difference between the diode laser and control groups. The amount of remaining filling material in the diode laser group was significantly lower than in the control group. When the other groups were compared, a significant difference was observed only between the diode laser and XPFF groups in the coronal third. Conclusion: No supplemental method could eliminate the root obturation material. The diode laser can be used in addition to nickel-titanium rotary retreatment systems to improve the removal of gutta percha and bioceramic sealer.

Assessment of Bond Strength of Different Bonding Systems to Eroded Dentin Using Sonic Activation: In Vitro Study

Abstract Objective Bonding to dentin is a great challenge, and erosion makes it difficult. This study evaluated the effect of sonic agitation on bond strength to eroded dentin using total etch (TE) and self-etch (SE) adhesive systems. Material and Methods A 96-sound human maxillary premolar teeth were prepared to obtain a flat dentin surface, randomly divided into two groups of 48 teeth each. One group was erosive demineralized with 0.05-M citric acid solution to produce an erodedlike dentin surface using de- and remineralization cycles, and the other group was considered a control with no erosive treatment. Each group was bonded with two different bonding strategies, TE (Single Bond 2) and SE (AdheSE One F). Each bonding system was applied with and without sonic activation, and the effect of bond agitation on shear bond strength (SBS) was tested after the application of composite to bonded dentin surface under shear load (0.5 mm/min). Two samples from each group were randomly selected for scanning electron microscopy (SEM) evaluation of the hybrid layer quality. An independent sample t-test was used to assess the effect of erosion, activation, and adhesive type on the SBS. Statistical significance was set at p &lt; 0.05. Result Concerning dentin substrate type, eroded dentin has lower SBS mean values than sound dentin, although it was not significant. Regarding the bonding strategy, TE produced higher SBS values than the SE bonding strategy; it was significant only in sound dentin; despite the bonding strategy and the substrate dentin type, sonic activation produced a significant rise in SBS values except when the SE bonding strategy was applied to eroded dentin where the rise was of no significant value (p &gt; 0.05). Conclusion Sonic agitation effectively improves the SBS value of composite bonded to eroded and sound dentin in both TE and SE strategies.

Comparing the remineralization potential of undemineralized dentin powder versus chicken eggshell powder on artificially induced initial enamel carious lesions: an in-vitro investigation

BackgroundWhite spot lesions are a widespread undesirable effect, especially prevalent during fixed orthodontic treatments. The study compared the in vitro enamel remineralization potential of undemineralized dentin matrix (UDD) versus chicken eggshell powder (CESP) for artificially induced enamel lesions.Methods100 caries-free and sound maxillary premolars were randomly divided into four groups each contain 25 teeth: Group I (Baseline): No treatment was done to the enamel surface. Group II (Negative control ): The enamel surface of the teeth underwent demineralization using demineralizing solution to create artificial carious lesions then kept in artificial saliva. Group III (CESP treated): After demineralizing the tooth surface, the teeth have been suspended in the CESP remineralizing solution. Group IV (UDD treated): After enamel demineralization, the teeth were suspended in UDD remineralizing solution. The remineralization potential was assessed by Vickers microhardness testing, scanning electron microscopic examination (SEM), and energy dispersive X-ray (EDX).ResultsThe current study demonstrated an increase in the mean microhardness of CESP and UDD-treated groups; however, It was nearer to the baseline level in the UDD group. SEM imaging revealed greater enamel remineralization in the UDD group compared to the remaining groups. The UDD group disclosed complete coverage for the prismatic enamel compared to the CESP group, which revealed a partially remineralized enamel surface. Interestingly, the Ca/P ratio increased significantly in the CESP group compared to the negative control group. In contrast, a higher significant increase in the mean Ca/P ratios was recorded in the UDD group compared to the test groups.Conclusionbiomimetic UDD and CESP powder should be utilized to treat enamel early carious lesions. However, UDD demonstrated the most significant remineralization potential.

PREPARO DO CANAL RADICULAR COM SISTEMA PRODESIGN LOGIC - RELATO DE CASO CLÍNICO

The objective of this study was to describe the preparation of root canals with a rotary system in a maxillary premolar. A 26-year-old patient, classified as ASA I, attended the Faculty of Dentistry of Pernambuco – FOP due to the presence of spontaneous pain in the region of the upper left first premolar. After clinical, radiographic examinations and sensitivity tests with an intense response, it was concluded that the probable diagnosis was symptomatic irreversible pulpitis. The preparation of the root canal was carried out with the ProDesign Logic rotary system and for this purpose, the Glide Path 25.01 file was used in order to explore the buccal and palatal canals. Odontometry was performed with the Root ZX apical locator (J.Morita) and confirmed by the radiographic method. The filling of the root canal system was performed using the single cone technique, 30.05 (HB). The final x-ray of the case was performed. It was concluded that the ProDesign Logic system determined a good shape of the canals, thus facilitating the filling of the root canal system.

Clinical assessment of monolithic zirconia crowns fabricated using an intraoral scanner.

This in vivo study assessed the accuracy of single-tooth monolithic zirconia crowns made using an intraoral scanner (IOS) and computer-aided design/computer-aided manufacturing (CAD/CAM) technology. Thirty patients requiring single posterior crowns were selected. The teeth were prepared with a deep chamfer finish line with a 1-mm extension subgingivally and a 1-mm reduction in all surfaces by one prosthodontist. The gingival margins were retracted using a gingival retraction paste before making impressions using a Trios scanner. All the digital impression files were sent to one laboratory using the dental designer software (3Shape, Copenhagen, Denmark). After completing the milling and sintering processes, the crowns were dyed and glazed. After removing the temporary crown, the qualitative assessment of proximal contacts of definitive monolithic zirconia crowns was performed according to the CDA criteria. Data were analyzed with Friedman's two-way analysis and independent t-test at α=0.05. The difference in axial and total gaps between premolar and molar teeth was not significant; however, the mean marginal gap of molars was higher than that of the premolars (P=0.043). Furthermore, the comparison of the axial, total, and marginal gaps between the upper and lower jaws showed no significant difference (P>0.05). The distribution of occlusal and proximal contacts indicated 60% and 66.7% proper contacts and no contacts in 6.7% and 10% of cases, respectively. Using IOSs could result in accurate monolithic zirconia crowns in terms of adaptation. Also, most occlusal and proximal contacts did not need any adjustments.

Effectiveness of XP-Endo Finisher, Endoactivator, and PUI agitation in the penetration of intracanal medicaments into dentinal tubules: A confocal laser scanning microscope analysis.

This investigation assessed the impact of irrigation activation systems on the depth of penetration of intracanal medicaments into dentinal tubules. Ninety-six mandibular premolar teeth were prepared using ProTaper Next up to size X3. The teeth were randomly divided into four groups based on the final irrigation activation systems (n=24): group 1: EndoActivator, group 2: XP-Endo Finisher, group 3: Passive ultrasonic irrigation (PUI), and group 4: control. After the final irrigation, all the samples were divided into two subgroups (n=12): subgroup A: calcium hydroxide (Ca(OH)2 ) and subgroup B: modified triple antibiotic paste (mTAP). Statistical analysis involved three-way analysis of variance (ANOVA). EndoActivator, XP-Endo Finisher, and PUI activation methods significantly increased the penetration of intracanal medicaments compared to conventional needle irrigation (P<0.05). The XP-Endo Finisher group exhibited the highest penetration percentage and maximum penetration depth, showing a statistically significant difference from the EndoActivator group (P<0.001). No significant difference was observed between XP-Endo Finisher and PUI, nor between PUI and EndoActivator (P>0.05). mTAP showed a higher percentage of dentinal tubule penetration than Ca(OH)2, although no significant difference was found in maximum penetration depth. The coronal region demonstrated the highest penetration percentage and depth, while the apical region showed the lowest. This study showed the effectiveness of XP-Endo Finisher in improving the penetration of intracanal medicaments into dentinal tubules. The findings emphasize the importance of selecting appropriate irrigation activation systems to improve treatment outcomes in endodontics. By demonstrating the effectiveness of advanced systems like XP-Endo Finisher, this research supports their integration into routine clinical practice for better endodontic success.

Comparative Evaluation of Different Obturation Techniques for Root Canal Filling of Permanent Teeth: An In-Vitro Study.

Achieving success in root canal (RC) therapy relies on three key components: comprehensive cleaning of the canal, efficient disinfection, and proper filling of the canal space. The present study aimed to compare the efficacy of four obturation techniques: single cone (SC), GuttaCore (GC), cold lateral condensation (LC), and C Point systemfor RC filling of permanent teeth. 76 extracted human mandibular first premolars were divided into four groups, with 19 teeth in each group (group A, obturation with SC technique; group B, obturation with GC; group C, obturation with LC; and group D, obturation with C Point system). The samples were marked at 4 mm and 8 mm from the root apex using a marker and calliper, sectioned horizontally, and analyzed under a stereomicroscope at 20x magnification. The mean percentage (%) of gutta-percha (GP)-filled area was compared using a two-way analysis of variance (ANOVA), followed by the Bonferroni post-hoc test. The mean percentage of GP-filled area at a distance of 4 mm from the apex was highest in group B (0.86±0.04; 95% CI: 0.845-0.881), followed by group D (0.70±0.07; 95% CI: 0.664-0.736), group A (0.61±0.05; 95% CI: 0.595-0.642), and least in group C (0.58±0.09; 95% CI: 0.543-0.627), and the difference was statistically significant (p≤0.05). The post-hoc pairwise comparison of groups at 4 mm revealed that there were statistically significant differences between group D and groups B, C, and A (p ≤ 0.001). The mean percentage of the GP area at a distance of 8 mm from the apex was highest in group B (0.81±0.10; 95% CI: 0.761-0.861), followed by group D (0.75±0.07; 95% CI: 0.725-0.792), group A (0.69±0.07; 95% CI: 0.658-0.729), and lowest in group C (0.65±0.10; 95% CI: 0.607-0.709), and this difference was statistically significant (p≤0.05). Post-hoc pairwise comparison of groups at 8 mm revealed that there was a statistically significant difference between groups D and C (p=0.006), whereas no statistically significant differences were noted between groups D and B (p=0.473). Furthermore, no statistically significant differences were noted between groups C and A at 4 mm and 8 mm (p>0.05). Obturation with the GC system provided the best results in terms of the percentage of GP-filled area at 4 mm. However, at 8 mm from the apical region, both the GC and C Point systems provided similar results.

Efficacy of different remineralization agents on microhardness and chemical composition of enamel white spot lesion

Background White spot lesions (WSLs) are frequently linked with low microhardness and mineral content changes. several strategies have been employed to deal with these problems. This investigation aimed to analyze the microhardness and mineral content changes after remineralization with bioactive glass (BAG) and casein phospho-peptide-amorphous calcium phosphate with fluoride (CPP-ACPF). Methods Twenty sound maxillary first premolars extracted were used to obtain a total of one hundred enamel samples. forty enamel slabs were split into four experimental groups (n = 10 each): Group I, BAG; Group II, BAG+CPP-ACPF; Group III, CPP-ACPF varnish; and Group IV, artificial saliva (negative control). To create artificial WSLs, all samples were preserved in a prepared demineralizing agent for 72 h before treatment with remineralizing agents. Vickers microhardness test was performed. Additionally, 60 enamel samples were selected for analysis using energy dispersive spectroscopy (EDX) and assigned to six experimental groups; the first four groups were similar to that used in the microhardness test along with Group V: WSLs, and Group VI: baseline. The statistical analyses employed in this study included Tukey’s HSD (p&lt;0.05), one-way ANOVA, and Shapiro-Wilk. Result Regarding surface microhardness, the BAG+CPP-ACPF group showed the most favorable recovery, which was better than the outcomes of the BAG and CPP-ACPF groups. A statistically significant change (p &lt;0.05) was not observed between them. Similarly, for mineral content change, the BAG+CPP-ACPF group demonstrated the greatest result, The BAG group came next, and the CPP-ACPF group came last. Conclusion The BAG+CPP-ACPF group might be regarded as the best course of treatment for enhancing both the surface microhardness and mineral content (Ca, P), while the control group (Artificial saliva) showed the least satisfactory results in comparison. After demineralization, mineral content and microhardness decreased in all samples. Therefore, BAG+CPP-ACPF significantly improved the surface microhardness and mineral content.

Evaluating the efficiency of mandibular molar protraction using Herbst appliances versus temporary anchorage devices: a retrospective case-controlled study

BackgroundMandibular second premolar agenesis is a common problem in orthodontics and is often treated in conjunction with maxillary counterbalancing extractions. However, in cases without maxillary crowding or dental protrusion, space closure may pose challenges leading to compromised occlusal results or patient profile. Multiple techniques have been described to treat these patients; nevertheless, there is a paucity of data comparing effectiveness of space closure utilizing various anchorage techniques. The goal of this study is to assess the effectiveness of the Herbst device during mandibular molar protraction and compare it to the use of temporary anchorage device (TADs) in patients with mandibular second premolar agenesis.Materials and methodsThis retrospective study included 33 patients with mandibular premolar agenesis treated without maxillary extractions. Of these patients, 21 were treated with protraction Herbst devices and 12 with TADs. Changes in molar and incisor positions, skeletal base positions and occlusal plane angulations were assessed on pretreatment (T0) and post-treatment (T1) lateral cephalograms. Scans/photographs at T0 and T1 were used to evaluate canine relationship changes representing anchorage control. Space closure and breakage/failure rates were also compared. Data was analyzed with paired and unpaired t-tests at the significance level of 0.05.ResultsWithin the Herbst group, changes in mandibular central incisor uprighting and mandibular molar crown angulations were statistically significant. However, no significant differences were noted between the Herbst and TAD groups. Protraction rates as well as overall treatment times were comparable (0.77 mm/month vs. 0.55 mm/month and 3.02 years vs. 2.67 years, respectively). Canine relationships were maintained or improved toward a class I in 82.85% of the Herbst sample, compared to in 66.7% of the TAD sample. Emergency visits occurred in 80.1% of the Herbst group, with cementation failures or appliance breakages as the most common reasons.ConclusionThe Herbst device could be a viable modality in cases with missing mandibular premolars where maximum anterior anchorage is desired, or if patients/parents are resistant to TADs. Furthermore, they could be beneficial in skeletal class II patients with mandibular deficiency who also need molar protraction. However, the increased incidence of emergency visits must be considered when treatment is planned.

Evaluation of root and root canal morphology in maxillary premolar teeth: A cone-beam computed tomography study using two classification systems in a Japanese population

Background/purposeInadequate knowledge increases the risk of overlooking root canals and causing procedural errors that can lead to root canal treatment failure. This study aimed to analyze the root and root canal morphology in maxillary premolar teeth using two classification systems assessed by cone-beam computed tomography (CBCT) in a large Japanese population. Materials and methodsThis study evaluated 1443 maxillary teeth including 726 first and 717 s premolars, from 642 Japanese individuals aged 16–84 years. CBCT images were analyzed according to the Vertucci and Ahmed classification systems, focusing on the root and root canal morphology. Variations were analyzed based on gender and age using the chi-square test (P < 0.05). ResultsMaxillary first premolars were predominantly single-rooted (64.9%) and had two root canals (86.2%). Females exhibited a higher prevalence of single-rooted (71.0%) compared to males (49.8%) (P < 0.05). Additionally, single root canals occurred significantly more frequently in females (14.0%) than in males (7.5%) (P < 0.05). Maxillary second premolars mostly had a single root (97.8%) with a single root canal (72.1%). The frequency of second premolars with two root canals significantly increased with age (P < 0.001). The three-rooted configuration occurred in 1.2% and 0.3% of the first and second premolars, respectively. ConclusionMaxillary premolars in a Japanese population showed significant anatomical variations, highlighting the importance of understanding anatomical characteristics specific to age and gender. Ahmed's system provides a more comprehensive description of the morphological variations.

Comparative analysis of remineralizing efficacy of strontium-doped bioactive glass, BioMin, and NovaMin containing dentifrice on artificial white spot lesions after chlorhexidine pretreatment - An in vitro study.

This study aimed to compare the remineralizing efficacy of strontium-doped bioactive glass, BioMin, and NovaMin containing dentifrices on artificial white spot lesions (WSLs) after chlorhexidine (CHX) pretreatment using energy-dispersive X-ray analysis (EDAX). Twenty-four samples of maxillary first premolars extracted for orthodontic purposes were selected. Artificial WSLs were produced by immersing the samples in a prepared demineralizing solution for 3 days. All the samples were pretreated with CHX and divided into four groups and six samples each. Group A treated with strontium-doped bioactive glass, Group B with BioMin, Group C with NovaMin, and Group D with artificial saliva as the control group for 14 days. pH-cycling model was used to simulate the oral cavity changes. EDAX was used to record the values at baseline, demineralization, and after remineralization. Data were analyzed using one-way ANOVA (post hoc), followed by unpaired t-test and Scheffe tests with Statistical Package for the Social Sciences version 16. Strontium-doped bioactive glass exhibited a greater mineral regain compared to BioMin, NovaMin, and control groups. Strontium-doped bioactive glass has enhanced mineral deposition on carious teeth and may provide an alternative clinical strategy for remineralizing early enamel lesions.

Estimating the validity of Tanaka-Johnston and Moyer's analysis of a Saudi sample.

Accurate estimation of unerupted permanent canines and premolars is a crucial step for effective orthodontic treatment planning during mixed dentition. This study aimed to evaluate the validity of Moyers' charts and the Tanaka-Johnston equation in predicting tooth sizes in a sample of the Madina population in Saudi Arabia and propose a new regression equation. Dental casts from 219 subjects (113 males and 106 females) were analyzed. Actual mesiodistal tooth widths were measured using digital calipers with an accuracy of 0.01 mm. Moyers' and Tanaka-Johnston predictions were compared with actual measurements, and a new set of prediction equations was developed. Tanaka-Johnston predictions consistently overestimated the actual measurements, exhibiting a difference of 1.20 mm for maxillary canines and premolars and a difference of 1.25 mm for mandibular teeth. The Moyers chart showed gender-specific variations with males aligning with the 50th percentile and females aligning with the 65th percentile for upper arches and the 50th percentile for lower arches. Newly derived linear regression equations were established for predicting the sum of upper and lower canines and premolars for the Madina population. The study highlights limitations in the Moyers and Tanaka-Johnston methods used for the current sample as both methods overestimated tooth sizes. New regression equations were developed to offer a more accurate approach for predicting tooth sizes for the study sample.

Fracture resistance of postendodontic restoration using self-adhesive bioactive resin and a bulk-fill composite with or without resin-impregnated glass fibers: An in vitro study.

Due to advancements in adhesive technology and the introduction of fiber reinforcement, there has been a paradigm shift towards a more minimally invasive approach in coronal restoration of endodontically treated teeth. This research aimed to evaluate and compare fracture resistance of postendodontic restoration using a self-adhesive bioactive resin and a bulk-fill composite with or without resin-impregnated glass fibers. Mesio-occlusal-distal cavities were prepared on 80 extracted human maxillary premolars. Root canal treatment was completed following standard access cavity preparation. Then, the teeth were divided into two groups based on the composite used for postendodontic restoration. Group I: Bulk-fill composite (Tetric N-Ceram). Group II: Activa BioActive. Group I and Group II were then divided into two subgroups depending on fiber incorporation (n = 20). Subgroup IA: Bulk-fill composite. Subgroup IB: Bulk-fill composite with fiber incorporation. Subgroup IIA: Activa BioActive. Subgroup IIB: Activa BioActive with fiber incorporation. The force required to fracture the teeth was recorded using the universal testing machine. Two-way ANOVA and Tukey's multiple post hoc test. Activa BioActive with fiber incorporation showed the highest mean fracture resistance (988.52N). Bulk-fill composite without fiber incorporation had the least mean fracture resistance (669.87N). Activa BioActive bulk-fill restorative material when used with the incorporation of resin-impregnated glass fibers can be a preferred material of choice for restoring endodontically treated teeth.

A comparative evaluation of human enamel remineralization ability of biomimetic nacre against casein phosphopeptide-amorphous calcium phosphate: An in vitro study.

This study aimed to assess and compare the efficacy of Nacre and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on the remineralization of enamel using surface microhardness analysis, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) spectroscopy. Twenty human maxillary premolars extracted for orthodontic reasons were collected. Under cool water spray, the crowns were sectioned mesiodistally into buccal and palatal halves using a diamond disc. The samples were subsequently mounted in self-cure acrylic resin. The samples were then subjected to Vickers hardness testing and SEM-EDX for baseline. To simulate carious lesions, all of the samples were acid-etched with 37% phosphoric acid for 30 s in a specific area on the enamel samples and subjected to surface microhardness testing and SEM-EDX. The enamel samples were randomly assigned to Group 1: Nacre water-soluble matrix (WSM), Group 2: Nacre varnish, and Group 3: CPP-ACP for remineralization. After 21 days, remineralization assessment of the test samples was done using SMH analysis and SEM-EDX analysis. Data obtained were statistically analyzed using the one-way analysis of variance to reveal the significant differences between the groups. Tukey's test was used for post hoc comparisons. All three groups showed a significant increase in surface microhardness. All three groups showed a significant calcium and phosphorous ratio increase after remineralization. Among the three groups, the highest Ca:P ratio was seen in the Nacre WSM group (0.58) followed by the Nacre Varnish (0.57) and CPP-ACP group (0.57). SEM images of the Nacre surface revealed the presence of extensive interlocking. A layer of packed hydroxyapatite particles was formed on the surface of the nacre through surface reactions. All the groups in the present study showed some extent of remineralizing ability irrespective of the different materials and mechanisms of action. Nacre WSM showed a remarkable hardness spike close to natural enamel after demineralization.

Comparative analysis of an epoxy resin-based and a premixed calcium silicate-based sealer's push-out bond strength with and without incorporation of chitosan nanoparticles: An in vitro investigation.

The aim of the study was to compare and evaluate the push-out bond strength (POBS) of epoxy resin-based and calcium silicate-based sealers with and without incorporating chitosan nanoparticles (CSNPs). Eighty human mandibular premolars with a single canal were taken. A standard root length of 15 mm was established. Canals were instrumented with Neoendo files up to size 30, 4% and were irrigated with 5 ml of 2.5% NaOCl, and 5 ml of ethylenediaminetetraacetic acid 17%. Then, samples were obturated using the size 30, 4% gutta-percha, single-cone technique using respective sealers. For POBS, it was grouped as Group 1 Adseal, Group 2 CeraSeal, Group 3 Adseal + 2% wt/vol CSNP, and Group 4 CeraSeal + 2% wt/vol CSNP. Samples embedded in acrylic resin were sectioned transversely at 11 and 7 mm from the apex. Dislodgment resistance was calculated using a universal testing machine. The data were analyzed using a one-way ANOVA test, followed by Tukey's post hoc analysis. The level of significance (P value) was set at P < 0.05. At 7 mm from the apex, Group 4 (CeraSeal + 2% wt/vol CSNP) demonstrated significantly higher mean POBS. However, no significant difference was observed between Groups 1 (Adseal), Group 2 (CeraSeal), and Group 3 (Adseal + 2% wt/vol CSNP). At 11 mm from the apex, Group 2 (CeraSeal) and Group 4 (CeraSeal + 2% wt/vol CSNP) demonstrated significantly higher mean POBS. On comparison between POBS at 7 mm and 11 mm from the apex, the mean POBS at the 11 mm region from the apex was significantly higher in all study groups, which was statistically significant. Within the limitations of the study, it has been concluded that Group 4 (CeraSeal + 2% wt/vol CSNP) has better bond strength compared to the other groups.