Exploring age and gender variations in root canal morphology of maxillary premolars in Saudi sub population: a cross-sectional CBCT study.

BACKGROUND: In complex teeth like maxillary premolars, endodontic treatment success depends on a complete comprehension of root canal anatomy. The research on mandibular premolars' root canal anatomy has been extensive and well-documented in existing literature. However, there appears to be a notable gap in available data concerning the root canal anatomy of maxillary premolars. This study aimed to explore the root canal morphology of maxillary premolars using cone-beam computed tomography (CBCT) imaging, considering age and gender variations. METHODS: From 500 patient CBCT scans, 787 maxillary premolar teeth were evaluated. The sample was divided by gender and age (10-20, 21-30, 31-40, 41-50, 51-60, and 61 years and older). Ahmed et al. classification system was used to record root canal morphology. RESULTS: The most frequent classifications for right maxillary 1st premolars were 2MPM1 B1 L1 (39.03%) and 1MPM1 (2.81%), while the most frequent classifications for right maxillary 2nd premolars were 2MPM1 B1 L1 (39.08%) and 1MPM1 (17.85%). Most of the premolars typically had two roots (left maxillary first premolars: 81.5%, left maxillary second premolars: 82.7%, right maxillary first premolars: 74.4%, right maxillary second premolars: 75.7%). Left and right maxillary 1st premolars for classes 1MPM1 and 1MPM1-2-1 showed significant gender differences. For classifications 1MPM1 and 1MPM1-2-1, age-related changes were seen in the left and right maxillary first premolars. CONCLUSION: This study provides novel insights into the root canal anatomy of maxillary premolars within the Saudi population, addressing a notable gap in the literature specific to this demographic. Through CBCT imaging and analysis of large sample sizes, the complex and diverse nature of root canal morphology in these teeth among Saudi individuals is elucidated. The findings underscore the importance of CBCT imaging in precise treatment planning and decision-making tailored to the Saudi population. Consideration of age and gender-related variations further enhances understanding and aids in personalized endodontic interventions within this demographic.

Patient-reported outcomes during accelerating the en-masse retraction of the upper anterior teeth using low-intensity electrical stimulation: a randomized controlled trial.

BACKGROUND: Low-intensity electrical stimulation (LIES) is considered a relatively recent technology that has received little attention in orthodontics as a method of acceleration. This study aimed to evaluate patient-reported outcome measures when LIES is used to accelerate the en-masse retraction of the upper anterior teeth. MATERIALS AND METHODS: The sample consisted of 40 patients (8 males, 32 females; mean age 21.1 ± 2.3 years), with Class II division I malocclusion who required extraction of the first premolars to retract upper anterior teeth. They were randomly assigned to the LIES group (n = 20) and the conventional en-masse retraction group (CER; n = 20). Patient responses regarding pain, discomfort, burning sensation, swelling, chewing difficulty, speech difficulty, and painkillers' consumption were recorded at these nine assessment times: 24 h (T1), 3 days (T2), and 7 days (T3) after force application, then in the second month after 24 h (T4), 3 days (T5), and 7 days (T6) of force re-activation, and finally after 24 h (T7), 3 days (T8), and 7 days (T9) of force re-activation in the third month. RESULTS: The mean values of pain perception were smaller in the LIES group than those in the CER group at all assessment times with no statistically significant differences between the two groups except during the second and third months (T5, T6, T8, and T9; P < 0.005). However, discomfort mean values were greater in the LIES group with significant differences compared to CER group during the first week of the follow-up only (T1, T2, and T3; P < 0.005). Burning sensation levels were very mild in the LIES group, with significant differences between the two groups at T1 and T2 only (P < 0.001). Speech difficulty was significantly greater in the LIES group compared to CER group at all studied times (P < 0.001). High levels of satisfaction and acceptance were reported in both groups, without any significant difference. CONCLUSION: Both the LIES-based acceleration of en-masse retraction of upper anterior teeth and the conventional retraction were accompanied by mild to moderate pain, discomfort, and chewing difficulty on the first day of retraction. These sensations gradually decreased and almost disappeared over a week after force application or re-activation. TRIAL REGISTRATION: ClinicalTrials.gov, ClinicalTrials.gov, NCT05920525. Registered 17 June 2023 - retrospectively registered, http://clinicaltrials.gov/study/NCT05920525?term=NCT05920525&rank=1 .

Evaluation of the effects of postprocessing settings in digital bitewing radiographs on proximal caries detection.

OBJECTIVE: Radiographs are an integral part of detecting proximal caries. The aim of this study was to evaluate the effect of contrast, brightness, noise, sharpness, and γ adjustment of digital intraoral radiographs on the diagnosis of proximal caries. MATERIALS AND METHODS: In this in vitro study, 40 extracted teeth including 20 premolars and 20 molars with enamel lesions (white spot or dentin discoloration seen through the enamel) were mounted together in groups of eight inside the skull. Bitewing radiographic images of each dental group were obtained by a photostimulable phosphor plate sensor with exposure conditions of 8 mA, 70 kV, and 0.2 s. The images were reconstructed by the built-in software and examined by two oral and maxillofacial radiologists in various settings of contrast, brightness, sharpness, noise, and γ. The teeth were then cut mesiodistally and the presence or absence of caries was confirmed by an oral and maxillofacial pathologist using a stereomicroscope. The data were then analyzed using the κ agreement coefficient, sensitivity, specificity, and accuracy (α = .05). RESULTS: Adjustment of brightness and contrast led to higher diagnostic performance with an accuracy of 82.5% and 83.8 (for observers 1 and 2, respectively) and 82.5% (for both observers), respectively. Noise adjustment was the least helpful approach for diagnosis of proximal dental caries among other adjustments, with an accuracy of 78.8% and 77.5% for observers 1 and 2, respectively. CONCLUSION: Brightness and contrast setting was more efficient in improving the diagnostic potential of bitewing radiographs compared to other adjustments.

Does surface priming increase the bond strength of orthodontic brackets? An experimental study.

OBJECTIVE: To evaluate the effects of metal primer II (MP II) on the shear bond strength (SBS) of orthodontic brackets bonded to teeth and bis-acryl composite provisional material (Bis-Acryl). MATERIAL AND METHODS: Twenty extracted human premolars specimens and 20 premolar shaped Bis-Acryl specimens were obtained and randomly divided into two surface groups. The first group consisted of human premolars (T) bonded to brackets in the conventional way while in the second (T-MP) MP II was applied on the bracket base before bonding. Similarly, one group of provisional material (PM) was prepared according to conventional treatment and another with the application of MP-II metal bonder (PM-MP). In all cases Ortho-brackets (Victory Series, 3 M) were bonded employing Transbond XT resin cement. Then the brackets were debonded under shear and the results were statistically analyzed by two-way analysis of variance and Holm Sidak at α = .05. The debonded surfaces of all specimens were examined by light microscopy and the Adhesive Remnant Index (ARI) was recorded. RESULTS: The SBS results exhibited significant differences er (p < .001). For both the T and TM the application of MP-II increased the SBS compared to respective control groups (p < .001). The T-C group was found inferior compared to PM-C (p < .001) and the same is true for the comparison between T-MP and PM-MP (p < .001). ARI indexes demonstrated that the tooth groups were characterized by a predominantly adhesive failure at the resin-dentin interface. In contrast, the control group for provisional crowns (PM-C) showed a predominantly cohesive failure mode, which moved to predominantly adhesive after the application of MP II. CONCLUSION: The application of MP II enhances the SBS on both, human enamel and provisional crown materials.

Comparison of the effects of fluoride varnish containing silver nanoparticles and conventional fluoride varnish on the surface microhardness of tooth enamel.

BACKGROUND: Nano-silver fluoride (NSF) has been introduced to improve enamel lesions. The effective use of varnishes is important in the prevention of dental caries. OBJECTIVES: The study aimed to compare the effect of conventional sodium fluoride varnish with the same varnish containing 1% and 2% silver nanoparticles (AgNP) on the surface microhardness of enamel. MATERIAL AND METHODS: The baseline surface microhardness of 40 premolar teeth was measured using a Vickers microhardness tester. After immersing the samples in a demineralizing agent for 24 h, the microhardness was measured again. In group B, a layer of conventional fluoride varnish was applied to the tooth surfaces using a microbrush with soft bristles, following the manufacturer's instructions. Groups C and D were treated with 1% and 2% NSF varnishes, respectively, while group A received no varnish. Surface microhardness tests were conducted on all specimens, including those previously tested. RESULTS: The microhardness of the enamel surface increased significantly in all 3 test groups compared to the microhardness after demineralization (p < 0.05). CONCLUSIONS: Conventional fluoride varnish and fluoride varnishes containing 1% and 2% AgNP are equally effective in remineralizing initial caries.

Comparison of the different methods of width estimation in unerupted canine and premolars.

BACKGROUND: There are different methods for determining the required space for unerupted teeth. However, the accuracy of these techniques varies depending on ethnic differences. Therefore, the current study was performed to compare the accuracy of four methods for estimating the mesiodistal width of unerupted canines and premolars in a population of northern Iran. METHODS: The present cross-sectional study was conducted on 50 pairs of dental casts of patients aged 12-24 years old. The mesiodistal width of the teeth was measured with a digital caliper by two observers (ICC < 0.9), and the mean value was recorded. The space required for eruption of canines and premolars was obtained by the Tanaka-Johnson formula and the Moyers tables and compared with the actual value by paired t test. RESULTS: The Tanaka-Johnson formula had overestimation in the maxilla and mandible, which was statistically significant (p < 0.001). The values obtained from the Moyers tables in different confidence levels were not accurate. However, the 65% level for the mandible had almost no difference from the actual value (P = 0.996 and r2 = 0.503). Furthermore, linear regression was obtained based on the total mesiodistal width of the maxillary first molar and mandibular central incisor (maxilla: Yx= 0.613X + 2.23 and mandible: Ym= 0.618X + 1.6) and the total mesiodistal width of the mandibular first molar and maxillary central incisor in each jaw (maxilla: Yx = 0.424X + 5.021 and mandible: Ym = 0.447X + 3.631). CONCLUSION: The Tanaka-Johnson method was overestimated in the population of northern Iran. The 85% and 75% confidence levels of the Moyers table have the best clinical results for the maxilla and mandible, respectively. Regression based on maxillary first molars and mandibular central incisors has better results.

Site selection of micro-implant anchorages in the infrazygomatic crest in adult orthodontic patients.

OBJECTIVES: To determine the optimal placement of miniscrews, this study compared adult male and female patients in terms of cortical bone density, cortical bone thickness, and available bone width in the infrazygomatic crest region. METHODS: The cone beam computed tomography imaging data of 200 patients (20-30 years old; 100 males and 100 females) were collected. The right maxillary posterior teeth in the sagittal plane were divided into six levels from proximal to distal, and three measurement sites were positioned at vertical distances of 8, 10, and 12 mm from the cementum. Cortical bone density, cortical bone thickness, and available bone width were measured in 18 measurement sites in the infrazygomatic crest and analyzed statistically. RESULTS: The highest cortical bone density, cortical bone thickness, and available bone width in the infrazygomatic crest in adult male and female patients were at the level of the interradicular space between the maxillary second premolar and maxillary first molar. The bone cortical density and thickness increased with vertical height, whereas the available bone width decreased with increasing vertical height. Differences were observed in cortical bone density, cortical bone thickness, and available bone width between adult male and female patients. CONCLUSIONS: The optimal implantation sites of the micro-implant anchorages in the infrazygomatic crest were at the level of the interradicular space between the maxillary second premolar and the maxillary first molar, and the vertical height of the optimal implantation site in males was appropriately higher than that in females.

Enamel Veneer Rehabilitation of a Premolar to an Incisor After Autotransplantation.

Tooth autotransplantation is one of the methods used for tooth loss rehabilitation in children. Premolars are usually used as autotransplants requiring esthetic alterations. The purpose of this paper is to present an innovative, alternative and inexpensive way to restore auto-transplanted teeth using the crown of the tooth of the recipient site. A seven-year-old male with a non-contributory medical history presented with an intrusion of his permanent maxillary right central incisor. The tooth underwent orthodontic extrusion using fixed appliances but eventually showed signs of ankylosis. At 10 years old, autotransplantation of a premolar to substitute the ankylosed incisor was undertaken. Six weeks after the autotransplantation, the premolar was restored to an incisor by modifying the extracted ankylosed tooth to a veneer for the transplanted tooth, providing functional and esthetic restoration. The patient has been followed up for two years without any complications. This technique can help clinicians restore autotransplants in an easy and esthetic manner.

Clinical efficacy of intraoral ultrasonography versus transgingival probing for measurement of gingival thickness in different gingival biotypes: a clinical trial.

BACKGROUND: Transgingival probing is conventionally used for gingival thickness (GT) measurement. However, invasiveness is a major drawback of transgingival probing. Thus, researchers have been in search of alternative methods for measurement of GT. This study compared the clinical efficacy of intraoral ultrasonography and transgingival probing for measurement of GT in different biotypes. MATERIALS AND METHODS: This clinical trial was conducted on 34 patients requiring crown lengthening surgery. GT was measured at 40 points with 2- and 4-mm distances from the free gingival margin (FGM) of anterior and premolar teeth of both jaws in each patient by an intraoral ultrasound probe. For measurement of GT by the transgingival probing method, infiltration anesthesia was induced, and a #25 finger spreader (25 mm) was vertically inserted into the soft tissue until contacting bone. The inserted length was measured by a digital caliper with 0.01 mm accuracy. All measurements were made by an operator with high reliability under the supervision of a radiologist. Data were analyzed by t-test, Power and Effect Size formula, and intraclass correlation coefficient (ICC). RESULTS: The two methods were significantly different in measurement of GT in both thick and thin biotypes at 2- and 4-mm distances (P < 0.001). The two methods had a significant difference in both the mandible (P < 0.001) and maxilla (P < 0.001) and in both the anterior (P < 0.003) and premolar (P < 0.003) regions. Although the difference was statistically significant in t-tests, the power and effect formula proved it to be clinically insignificant. Also, the ICC of the two methods revealed excellent agreement. CONCLUSION: The results showed optimal agreement of ultrasound and transgingival probing for measurement of GT. TRIAL REGISTRATION: The study was approved by the ethics committee of Shahid Beheshti University of Medical Sciences on 2021-12-28 (IR.SBMU.DRC.REC.1400.138) and registered in the Iranian Registry of Clinical Trials on 2022-03-14 (IRCT20211229053566N1).

Bleaching versus color change resistant adhesive in the discoloration of bracket-bonded tooth surfaces: an in vitro study.

OBJECTIVES: The aim of this study was to compare the effect of office bleaching of teeth bonded with Transbond XTTM (3M Unitek, Monrovia, CA, USA) (TRXT) and the use of color change resistant Orthocem (FGM, Joinville, Brazil) in bracket bonding on coffee-induced enamel discoloration. MATERIALS AND METHODS: Eighty premolars were distributed in equal numbers (n = 20) to group 1 (TRXT + distilled water), group 2 (TRXT + coffee solution), group 3 (TRXT + coffee solution + bleaching), and group 4 (Orthocem + coffee solution). Color was measured using a SpectroShade Micro (MHT, International, Verona, Italy) device at the beginning (T0), after coloring (T1), after bleaching (T1B), and after debonding (T2). ΔE color change values were calculated as T1-T0, T1B-T0 and T2-T0 differences. The conformity of the data to the normal distribution was examined with the Shapiro-Wilk test. Multiple comparisons were made with Tamhane's T2 test and Tukey's HSD test using one-way analysis of variance in the comparison of normally distributed data, and multiple comparisons were made with Dunn's test using the Kruskal-Wallis H test for comparison of non-normally distributed data. The significance level was set at p < 0.050. RESULTS: A statistically significant (p < 0.001) difference was found between the T1-T0 and T2-T0 stages for group 1-4 ΔE values. A statistically significant (p < 0.001) difference was also found when the T1B-T0 ΔE values of group 3 were compared with the T1-T0 ΔE values of groups 1, 2, and 4. CONCLUSIONS: After coffee-induced enamel discoloration, bleaching of teeth bonded with TRXT produced acceptable color difference of the incisal, middle, and gingival regions of the crown. In teeth bonded with Orthocem, acceptable color difference was seen only in the middle of the crown. CLINICAL RELEVANCE: The presented study will guide the clinician on how enamel discoloration side effect of fixed orthodontic appliance can reduce.

Effects of different primers and colouring solutions on orthodontic bonding: shear bond strength and colour change.

OBJECTIVES: This in vitro study evaluated the effect of different colouring solutions and primer systems used in the bonding of brackets on enamel colour change and bond strength. MATERIALS AND METHODS: 120 premolar teeth were divided into four main groups; brackets were bonded with 37% orthophosphoric acid + Transbond XT Primer in Group 1, 3 M Single Bond Universal in Group 2, Transbond Plus SEP in Group 3, and G-Premio Bond in Group 4. Each group was divided into three subgroups, and the teeth were placed in a cup containing coffee and tea mixture, in a cup containing cola and in distilled water. A bond strength test was applied to all teeth. Colour measurements of all teeth were performed at 2 different times: before bonding and after the bond strength test. RESULTS: The average bond strength of the 37% orthophosphoric acid group was higher than that of the other groups. The effect of primer and solution groups on colour change was statistically significant (p = 0.001 and p = 0.023, respectively). CONCLUSIONS: In this study, the bond strength was clinically sufficient in all primer groups. The highest colour change was observed when the tea-coffee solution and Transbond Plus SEP primer were used. CLINICAL RELEVANCE: This study has identified enamel discoloration and bond strength from different colouring solutions and primer systems used for bonding braces, which can be used to inform clinicians and patients to achieve better treatment results.

A novel surgical treatment approach for the vertical root fracture of posterior teeth: a case report with 24-month review.

BACKGROUND: Up to 25% of the tooth extraction after root canal treatment could be attributed to the vertical root fracture (VRF). The treatment choice for teeth with VRF would mostly be the extraction despite some repairing methods were also reported. The repairing treatment result of VRF would mostly depend on the fixation strength and the bioactivity of the repairing materials, especially for the posterior teeth with high masticating stresses. This case report designed a novel surgical treatment approach for the VRF of posterior teeth. METHODS: a maxillary premolar with buccal-palatal complete VRF was treated with a new dual-layered repairing approach using adhesive resin + iRoot BP Plus bioceramic cement to fill the modified fracture line with retention forms through the intentional replantation. RESULTS: At the 24-month review, the tooth showed desirable periodontal healing and normal function. CONCLUSIONS: This case report indicated that the dual-layered repairing approach might be effective for saving the posterior teeth with VRF. Nevertheless, further clinical trials are needed for its long-term result.

Shape variation in modern human upper premolars.

Morphological variation in modern human dentition is still an open field of study. The understanding of dental shape and metrics is relevant for the advancement of human biology and evolution and is thus of interest in the fields of dental anthropology, as well as human anatomy and medicine. Of concern is also the variation of the inner aspects of the crown which can be investigated using the tools and methods of virtual anthropology. In this study, we explored inter- and intra-population morphometric variation of modern humans' upper third and fourth premolars (P3s and P4s, respectively) considering both the inner and outer aspects of the crown, and discrete traits. We worked by means of geometric morphometrics on 3D image data from a geographically balanced sample of human populations from five continents, to analyse the shape of the dentinal crown, and the crown outline in 78 P3s and 76 P4s from 85 individuals. For the study of dental traits, we referred to the Arizona State University Dental Anthropology System integrated with more recent classification systems. The 3D shape variation of upper premolar crowns varied between short and mesio-distally broad, and tall and mesio-distally narrow. The observed shape variation was independent from the geographical origin of the populations, and resulted in extensive overlap. We noted a high pairwise correlation (r1 = 0.83) between upper P3s and P4s. We did not find any significant geographic differences in the analysed non-metric traits. Our outcomes thus suggest that geographical provenance does not play a determinant role in the shaping of the dental crown, whose genesis is under strict genetic control.

Assessment of dental pulp response to carries via MR T2mapping and histological analysis.

OBJECTIVES: The aim of our study was to assess the correlation between T2 relaxation times and their variability with the histopathological results of the same teeth in relation to caries progression. MATERIALS AND METHODS: 52 extracted permanent premolars were included in the study. Prior to extractions, patients underwent magnetic resonance imaging (MRI) scanning and teeth were evaluated using ICDAS classification. Pulps of extracted teeth were histologically analysed. RESULTS: MRI T2 relaxation times (ms) were 111,9 ± 11.2 for ICDAS 0, 132.3 ± 18.5* for ICDAS 1, 124.6 ± 14.8 for ICDAS 2 and 112. 6 ± 18.2 for ICDAS 3 group (p = 0,013). A positive correlation was observed between MRI T2 relaxation times and macrophage and T lymphocyte density in healthy teeth. There was a positive correlation between vascular density and T2 relaxation times of dental pulp in teeth with ICDAS score 1. A negative correlation was found between T2 relaxation times and macrophage density. There was a positive correlation between T2 relaxation time variability and macrophage and T lymphocyte density in teeth with ICDAS score 2. In teeth with ICDAS score 3, a positive correlation between T2 relaxation times and T2 relaxation time variability and lymphocyte B density was found. CONCLUSION: The results of our study confirm the applicability of MRI in evaluation of the true condition of the pulp tissue. CLINICAL RELEVANCE: With the high correlation to histological validation, MRI method serves as a promising imaging implement in the field of general dentistry and endodontics.

Evaluation of Retentive Strength of 50 Endodontically-Treated Single-Rooted Mandibular Second Premolars Restored with Cast Post Cores Using 5 Common Luting (Cement) Agents.

BACKGROUND A luting agent is a dental cement used to secure a dental restoration. This study aimed to evaluate retentive strength of 50 endodontically-treated single-rooted mandibular second premolars (extracted) restored using 5 common luting (cement) agents. MATERIAL AND METHODS Fifty single-rooted mandibular second premolars with adequate root length and uniform size/shape were decoronated. After completing endodontic biomechanical preparation and obturation, root canals of all specimens were prepared to receive a cast post core. Depending upon cementation type, CPC specimens were divided in 5 groups (10 each) (Gp): Zinc phosphate (Gp ZP), polycarboxylate (Gp PC), glass ionomer (Gp GI), resin-modified glass ionomer (Gp RGI), and resin cement (Gp RC). Retentive strength was determined using the adhesive failure pull-out test. Mean/standard deviations were calculated for tensile forces (in kilograms) and differences were determined using analysis of variance (ANOVA). Multiple comparison was performed using the t test. A P value of ≤0.05 indicated a statistically significant difference. RESULTS The order of mean tensile strength from higher to lower was Gp RC (21.46) >Gp RGI (18.17) >Gp GI (16.07) >Gp ZP (15.33) >Gp PC (13.63). Differences in retentive strengths between the cements were significant (P≤0.05). Multiple-group comparisons showed that except for Gp ZP and Gp GI, all groups differed significantly from each other. CONCLUSIONS All investigated cements provided optimal retentive strengths, with wide differences between them. Resin cements should be used when CPC removal is not anticipated, while polycarboxylate or zinc phosphate should be used if CPC removal is anticipated.

Changes in periodontal parameters of splinted versus non-splinted posterior teeth during ten years of supportive periodontal therapy - A retrospective evaluation.

OBJECTIVES: To compare periodontal parameters of splinted posterior teeth versus control teeth over ten years of supportive periodontal therapy (SPT) and to assess the survival rate of splints. MATERIAL AND METHODS: Retrospective data of 372 SPT-patients was screened for splints (composite/fiberglass-reinforced composite) in the posterior (molars/premolars) which were inserted at least ten years before due to increased tooth mobility. For each splinted tooth (test), a corresponding control tooth had to be present at the first SPT-session after splint insertion (T1). Data was assessed at T1 and ten years later (T2). Possible influencing covariates for splint survival (mobility degree/Eichner class) were tested by Cox regression. The change in clinical attachment level (ΔCAL), probing pocket depth (ΔPPD) and the testing of possible influencing covariates was analyzed by using mixed linear regression. RESULTS: Twenty-four patients (32 splints, 58 splinted teeth) were included. Ten test and two control teeth were lost. No differences were observed between ΔCAL and ΔPPD of test teeth compared to control teeth (ΔCAL -0.38 ± 1.90 vs. 0.20 ± 1.27 mm; ΔPPD -0.17 ± 1.18 vs. 0.10 ± 1.05 mm). Twenty-two splints fractured during the observation period (survival-rate: 31%). Mobility degree and Eichner class did not influence time until fracture. CONCLUSIONS: Splinting of periodontally compromised and mobile posterior teeth does not have any disadvantage regarding the clinical periodontal situation when regular SPT is applied. However, splint fractures occur very often. CLINICAL RELEVANCE: Splinting of posterior teeth is a treatment option in addition to active periodontal therapy when patients are disturbed by tooth mobility but splints have a high susceptibility to fracture.

Evaluation of enamel surface integrity after orthodontic bracket debonding: comparison of three different system.

OBJECTIVE: This study aimed to evaluate enamel surface integrity and time consumed during residual cement removal after bracket debonding using different adhesive removal burs with and without a dental loupe. MATERIAL AND METHODS: Sixty human-extracted premolars were collected, cleaned, mounted, and prepared for orthodontic bracket bonding. Teeth were randomly divided into three main groups (n = 20) based on the adhesive removal method: tungsten carbide system (TC), sof-lex discs system (SD), and diamond system (DB) groups. Then, each group was subdivided into two subgroups (naked eye and magnifying loupe subgroups). The brackets were bonded and then debonded after 24 h, and the Adhesive Remnant Index (ARI) was assessed. The adhesive remnants were removed by different systems, and the final polishing was performed by Silicone OneGloss. The enamel surface roughness was evaluated before bracketing (T0), after residual cement removal (T1), and finally after polishing (T2) using surface Mitutoyo SJ-210 profilometry and Scanning Electron Microscopy (SEM) to determine the Enamel Damage Index (EDI) score. The time consumed for adhesive removal was recorded in seconds. RESULTS: The Kruskal Wallis test showed a statistically significant difference in roughness values at T1 compared to T2 between subgroups (p < 0.001). When comparing EDI at T1 and T2, the Kruskal-Wallis H-test showed statistically significant differences in all subgroups. The pairwise comparisons revealed that EDI scores showed a statistically significant difference at T1 and T2 between DB vs. TC and SD (p = 0.015) but not between TC vs. SD (p = 1.000), indicating the highest roughness value observed in the DB group. The time for cement removal was significantly shorter in the magnifying loupe group than in the naked eye group and was shortest with the TC group, whereas the time was the longest with the DB group (p < 0.05). CONCLUSION: All three systems were clinically satisfactory for residual orthodontic adhesive removal. However, TC system produced the lowest enamel roughness, while the DB system created the greatest. The polishing step created smoother surfaces regardless of the systems used for resin removal.

Clinical challenges of biomechanical performance of narrow-diameter implants in maxillary posterior teeth in aging patients: A finite element analysis.

This study evaluated the biomechanical performance of narrow-diameter implant (NDI) treatment in atrophic maxillary posterior teeth in aging patients by finite element analysis. The upper left posterior bone segment with first and second premolar teeth missing obtained from a patient's cone beam computed tomography data was simulated with cortical bone thicknesses of 0.5 and 1.0 mm. Three model groups were analyzed. The Regimen group had NDIs of 3.3 × 10 mm in length with non-splinted crowns. Experimental-1 group had NDIs of 3.0 × 10 mm in length with non-splinted crowns and Experimental-2 group had NDIs of 3.0 × 10 mm in length with splinted crowns. The applied load was 56.9 N in three directions: axial (along the implant axis), oblique at 30° (30° to the bucco-palatal plane compared to the vertical axis of the tooth), and lateral load at 90° (90° in the bucco-palatal plane compared to the vertical axis of the tooth). The results of the von Mises stress on the implant fixture, the elastic strain, and principal value of stress on the crestal marginal bone were analyzed. The axial load direction was comparable in the von Mises stress values in all groups, which indicated it was not necessary to use splinted crowns. The elastic strain values in the axial and oblique directions were within the limits of Frost's mechanostat theory. The principal value of stress in all groups were under the threshold of the compressive stress and tensile strength of cortical bone. In the oblique and lateral directions, the splinted crown showed better results for both the von Mises stress, elastic strain, and principal value of stress than the non-splinted crown. In conclusion, category 2 NDIs can be used in the upper premolar region of aging patients in the case of insufficient bone for category 3 NDI restorations.

Impact of Access Cavity Design on Fracture Resistance of Endodontically Treated Maxillary First Premolar: In Vitro.

This study was designed to investigate the impact of access cavity designs on fracture resistance of endodontically treated maxillary first premolars. The study sample consisted of 72 intact maxillary first premolars, randomly divided into six groups (n = 12). A standardized proximal cavity preparation was prepared for all samples using standard bur. Groups I: control group with only standard proximal cavity and no endodontic access, group II: Truss access cavity, group III: Separated access to buccal and palatal canals without removal of dentine in between, group IV: Access to buccal and palatal canals with removal of dentine in between, group V: Traditional access cavity, group VI: Mesio-occlusal-distal cavity (MOD). For groups I and VI, only composite restoration was used to restore the proximal cavity, while for groups II- V, the access was prepared and endodontic treatment was performed on all teeth, then composite restoration was placed. The root canals were instrumented using nickel-titanium files, irrigated with sodium hypochlorite, and filled with AH plus sealer and gutta-percha using warm vertical condensation. All samples were then placed in an acrylic mold and underwent thermal aging for 10,000 cycles between 5 and 55°C. The samples were fixed in a universal testing machine with the long axis of the roots positioned at 20° to a load applied at a crosshead speed of 1 mm/min using a stainless steel semi-spherical indenter (Ø = 3 mm) until fracture occurred to determine the fracture resistance force in Newton. The normality test (Shapiro-Wilk) showed that data are normally distributed. Group II exhibited the highest mean fracture resistance, and group VI was the least likely to resist the fracture. No statistically significant differences between tested groups (p-value = 0.237). The MOD group showed a more unfavorable mode of fracture compared to other groups. No significant difference in fracture resistance between conservative and traditional access cavities. The missing marginal ridges, such as in MOD cavities played an important role in decreasing the fracture resistance of endodontically treated teeth.

Minimally invasive surgical removal of bilateral impacted mandibular supernumerary teeth using 3D surgical guide template: a case report.

Impacted supernumerary teeth are defined as the presence of one or more teeth in a patient's upper and lower jaws in addition to the normal number of teeth in the dental arch. It has an incidence rate of approximately 1%-14% and more frequently occurs in males than females, may be single or multiple, unilateral or bilateral, erupted or impacted. In this article, we describe the case of a patient with two supernumerary teeth between the roots of the mandibular second premolar and the first molar, which influenced the effectiveness of the first orthodontic treatment. The special anatomical position of the complex supernumerary teeth made tooth extraction challenging. Given the higher risk status of surgery, we implemented a novel tooth extracting technique for this patient. Thus, in this study, we describe a case of minimally invasive extraction of bilateral mandibular impacted supernumerary teeth using a digital 3D positioning guide plate.