Incisal Edge Research Articles

Influence of Using a Puncturing Method and Cooldown Period Before Pressing the Second-Layered Sheet on the Final Thickness of Double-Layered Sports Mouthguards: An Experimental Study.

The thickness of the mouthguard is a crucial factor in its protective ability for athletes. This study aimed to investigate the final thickness of double-layered sports mouthguards, which were fabricated using different methods before pressing the second layer. Seven upper working models (n = 7 per group) were prepared for mouthguard fabrication. The first 3-mm mouthguard sheet underwent heating, pressing, and vacuuming onto the model, followed by various protocols before the second 3-mm sheet was pressed. Group 1: The second sheet was pressed immediately. Group 2: The first sheet underwent a 1-h cooldown period before pressing the second sheet. Group 3: The interproximal areas of the first sheet were punctured followed by immediate pressing of the second sheet. Group 4: The first sheet was punctured followed by a 1-hcooldown before pressing the second sheet. After 24 h, the mouthguard thickness was measured at various points on the left and right central incisors and first molars using a digital caliper. The thickness analysis was performed using SPSS 29.0 with one-way ANOVA and Tukey post hoc analysis. At the labial surface of the central incisors, Group 4 exhibited the highest thickness, while Group 3 had the lowest (p < 0.001). Groups 1 and 2 did not show significant differences in thickness. At the incisal edges, Group 3 again had the lowest thickness (p < 0.05), with no significant differences observed among the other groups. There were no significant differences in thickness across all areas at the first molars, including cusp tips, pits, and buccal surfaces (p > 0.05). Group 4 demonstrated greater uniformity at the central incisors in thickness compared with the other groups. Using the puncturing method at interproximal areas combined with a cooldown period could enhance mouthguard thickness at the labial surfaces of the central incisors and improve its thickness uniformity.

Dental arch shape in twins: A morphometric study of genetic influences

The objective of this study was to assess the relative contribution of genes to shape variation in the permanent dental arches in individuals of Western European descent. The dental casts from 64 monozygotic and 38 dizygotic twins, housed in the Adelaide Dental School's twin record collection, Australia, were assessed. The subjects were of Western European descent, with a mean age of 19.4 ± 5.4 years. Dental casts were scanned using a 3-dimensional scanner (3Shape E4, 3Shape, Copenhagen, Denmark), and landmarks were placed on incisal edges and cusp tips of canines, premolars, and molars. Procrustes superimposition and principal components analysis were applied to examine shape variation. Two-block partial least-squares analysis was used to assess shape covariation between arches. Structural equation modeling was utilized to decompose observed shape variation into genetic and environmental components using the normal assumptions of the twin model. The first 3 principal components (PCs) of the maxillary and mandibular arch were meaningful, accounting for 53% and 50% of the variation in shape space, respectively. The PCs represented shape variability as follows: PC1 - arch depth-width ratio, PC2 - arch taper, canine position (and first premolar rotation for the mandibular arch), and PC3 - incisor displacement and rotation. Genetic modeling indicated that a model incorporating additive genetic and unique environmental factors optimally explained the observed variation for all meaningful PCs. Within shape space, most of the variation in maxillary and mandibular arches exhibited moderate to high heritability (h2= 0.61-0.74). Maxillary and mandibular dental arches had strong and significant shape covariation, with high heritability in their reciprocal influences on shape (h2= 0.72-0.74; rpls coefficient= 0.87; P<0.05). In this cohort, dental arch shape variation was predominantly influenced by genetic factors. High covariation and heritability were observed between the maxillary and mandibular dental arches. This information may help inform decisions around orthodontic intervention.

Reference points to evaluate changes in the upper lip after labial incisor movement between tipping and translation in crowding patients: A retrospective study

ObjectiveThis study aimed to compare the changes of reference points on the labial surface of upper incisors (U1) to upper lip (UL) after U1 labial movement between a translation group (TSL) and tipping group (TIP). Correlations between changes in U1 and UL were determined. MethodsLateral cephalometric radiographs were selected and divided into TSL and TIP groups by pre- and post-treatment superimpositions. Skeletal, dental, and soft tissue of pre- and post-treatment treatment and variables were evaluated. Independent t-test and Wilcoxson test were applied for the statistical analysis between TSL and TIP. Spearman’s correlation coefficients and multiple linear regression analysis were used to verify the association between lip profile changes and other variables in TSL and TIP group separately. ResultsAfter U1 labial movement, the incisal edge (LaU1e), middle (LaU1m), and cervical (LaU1c) points of TSL moved evenly labially, whereas the TIP group had incisal edge that moved greater labially than the middle and cervical points. UL moved more labially in TSL (0.87–1.05 mm) than the TIP (0.31–0.41 mm). UL changes to the E-line in TSL showed significant positive correlations to all three LaU1(e, m, c)-SnTV changes. In the TIP group, only a positive correlation presented for the LaU1m-SnTV and LaU1c-SnTV changes. Nevertheless, Multiple linear regression analysis indicated the unfeasibility of predicting the upper lip changing ConclusionLaU1e in TSL and TIP moved almost equally labially but less labially in TIP at the middle and cervical points. The UL moved more labially in TSL than TIP. Rather than using the incisal edge to estimate upper lip changes, it would be better to use the middle and cervical points of U1, which coincide with Labrale superioris (Ls).

Use of hyperboloid as an adjunct in functional jaw orthopedics – case report

Anterior open bite can be defined as a malocclusion with a negative vertical discrepancy between the incisal edges of the upper and lower anterior teeth, which do not have occlusal contacts with the antagonists and sometimes extends to the canines and, less frequently, to the premolars is one of the malocclusions with the greatest aesthetic and/or functional impairment. Anterior open bite can have several etiologies: finger sucking and/or pacifier, oral breathing, onychophagia, lip interposition, atypical swallowing, tongue interposition when uttering phonemes and anterior posture of the tongue at rest. Orofacial myofunctional disorders are present in cases of anterior open bite, generally associated with etiologies and adapt to this altered morphological condition. Regarding the anterior opening amplitude, the anterior open bite is classified as: minimum up to 1 mm, moderate between 1 and 5 mm and severe +5 mm [1]. Open bite can be classified into: maxillary, mandibular and hybrid open bite [2]. Myofunctional therapy is considered a treatment method that can increase muscle strength, cause changes in functional patterns and thus prevent deviations in craniofacial development, as it promotes new posture of structures at rest and during the performance of the functions of the stomatognathic system [3]. The hyperboloid is an instrument for increasing muscle tone and when used in chewing, it is efficient in inducing growth and remodeling. The hyperboloid fills a gap in the modern diet, with the consistency of hard, raw and dry foods [4]. Exercises with a size M hyperboloid with wire were prescribed as an initial approach. After 2 months of treatment, there was an improvement in the interincisor distance. The exercise was maintained for another 5 months. He stopped attending appointments for 2 years and 2 months. Upon his return, the results of the functional examination of swallowing, chewing, protrusion and laterality were observed, and we opted for the installation of the SN3. the hyperboloid, in this case, showed its efficiency in balancing the stomatognathic system.

The "Smile Design and Space" Concept for Altering Vertical Dimension of Occlusion and Esthetic Restorative Material Selection.

This article introduces the smile design and space (SDS) concept for managing the vertical dimension of occlusion (VDO) in full-mouth reconstructions and its influence on the selection of esthetic restorative materials. Limitations of traditional VDO adjustment methods are being addressed through a facially driven treatment approach that enhances esthetics improves function and minimizes invasiveness. The SDS concept involves detailed evaluations of the incisal edges of the maxillary central incisors in relation to the upper lip at rest and at full smile. This includes analyzing variations in incisal exposure due to differing lip mobility, which can significantly impact gingival esthetics, particularly in cases with gingival exposure during smiling. The concept employs a strategic formula to determine the necessary alterations in VDO based on specific dental relationships and wear patterns. The SDS concept provides guidelines for full-mouth reconstructions, emphasizing minimal invasiveness and the integration of esthetics with functional dynamics to enhance the predictability of clinical outcomes and reduce complications associated with traditional restoration techniques. The SDS concept enhances the precision of full-mouth reconstructions through individualized adjustment of the VDO, tailored to the esthetic and functional requirements of each patient.

Efficacy and complications of endoscopic thoracoscopic versus laparoscopic radical esophagectomy in esophageal cancer treatment: A retrospective study.

To evaluate the efficacy and postoperative complications of endoscopic thoracoscopic and laparoscopic radical esophagectomy compared to open surgery in esophageal cancer treatment. This retrospective study included 103 esophageal cancer patients admitted from August 2018 to March 2022, divided into observation (endoscopic surgery) and control (open surgery) groups. We compared intraoperative parameters, postoperative outcomes, immune function, and one-year overall survival (OS). Intraoperative bleeding volume, the retention time of chest tube, postoperative fasting time, and hospital stay in the observation group were smaller than those in the control group (P < .05). The differences were not statistically significant (P > .05) when comparing operative time, the number of intraoperative blood transfusion cases, and the rate of operating room extubation in these 2 groups. The differences were not statistically significant when comparing the amount of resected lymph nodes and the positive rate of incisal edge in these 2 groups (P > .05). There was no statistically significant difference in the complication rates such as pneumonia, pleural effusion, pneumothorax, pulmonary embolism, anastomotic fistula, the leakage of thoracic duct, the injury of RLN and arrhythmia in these 2 groups (P > .05). At 7 days postoperatively, the CD4+ and CD4+/CD8+ in the observation group and the control group were smaller than the preoperative ones in their same groups, and they were larger in the observation group than those in the control group (P < .05); There was no statistically significant difference on the CD8+ in the observation group and the control group at 7 days postoperatively compared with the preoperative ones in their same groups (P > .05). The 1-year postoperative OS rate was 81.63% (40/49) in the observation group and 72.22% (39/54) in the control group, and the difference was not statistically significant when comparing the OS rates of these 2 groups (P = .238, HR = 0.622, 95% CI = 0.279-1.385). Endoscopic thoracoscopic and laparoscopic esophagectomy offers less invasive treatment with significant short-term benefits and better preservation of immune function in esophageal cancer patients, making it a safe and effective surgical option.

EVALUATION OF THE RELATIONSHIP OF CURVE OF SPEE WITH DENTOSKELETAL MORPHOLOGY IN SAGITTAL MALOCCLUSIONS

Curve of Spee is defined as the line on a cylinder which is tangent to incisal edges of lower anteriors, occlusal surface of lower second molar and anterior border of condyle. The aim of the study is to determine whether there is a relationship between curve of Spee and craniofacial morphology in different sagittal malocclusions and to determine the influence of craniofacial morphological features in different sagittal malocclusions on curve of Spee. The research consists in the analysis of lateral cephalograms and study models of 90 patients, age 15-25 years which includes skeletal class I, class II and skeletal class III. Patients are divided into three groups: group A-flat curve of Spee i.e. &lt; 2mm, group B - normal curve of Spee i.e. 2-3 mm, and group C - deep curve of Spee i.e. &gt;3mm. In the literature, there is little data on research that has been done on this topic, on the other hand, in our daily work as orthodontists, we encounter the problem of leveling the deep bite.

Impact of labially inclined implant axes on immediate implant placement and provisionalization in anterior maxilla: A prospective cohort study.

To investigate whether a labially inclined implant axis compromises the clinical outcomes of immediate implant placement and provisionalization (IIPP) in the anterior maxilla. Patients with unsalvageable central or lateral maxillary incisors were enrolled. IIPP with simultaneous connective tissue graft (CTG) was performed in all participants. In the control group, the alveolar ridge had a long axis aligned with the tooth, which ensured that the immediate implant was aimed at the incisor edge or the cingulum of future restoration. The test group had a large angle between the axes of the ridge and tooth. To avoid bone fenestration, the implants were placed labially inclined and emerged from the labial side of future restoration. Intra-oral scanning and cone-beam computed tomography were performed to record soft and hard tissue profiles at baseline and 1 year later. Soft tissue stability, bone remodeling, and pink esthetic score (PES) were evaluated and compared between two groups. Thirty-nine participants (19 tests and 20 controls) completed the study. At 1-year post-surgery, the mid-facial gingival margin migrations were 0.85 ± 0.37 mm (test) and 0.81 ± 0.33 mm (control), without significant differences. No differences were identified in buccal profile alteration, linear ridge reduction, buccal bone thickness, or PES scores. The test group demonstrated thinner buccal soft tissue at the crestal level than the control group. When large tooth-ridge angulation presented, labially inclined implant, avoiding buccal ridge fenestration in IIPP with CTG, did not compromise the clinical outcome in short term.

Monson’s sphere in Chinese young adult females with individual normal occlusion: a preliminary study using digital models

BackgroundThis study investigated the characteristics of Monson’s sphere in Chinese young adult females with individual normal occlusion to provide a reference for oral rehabilitation in prosthodontic and orthodontic treatments.MethodsPoints at the dental cusps and incisal edges were selected from 51 digital mandibular dental models of Chinese young adult females (aged 18–22 years) with individual normal occlusion. Monson’s spheres were fitted to the selected points based on the least-squares principle and the radii were calculated. The deviation of each selected point from its relative spherical surface was also calculated. The radii and deviations of these points were examined using conventional descriptive statistics and distributions of the most deviated points inside and outside the spheres were analyzed.ResultsThe mean radius of Monson’s sphere in Chinese young adult females was 79.60 ± 14.13 mm. The deviation of each selected point from its relative sphere surface was 0.38 ± 0.30 mm. The maximum deviations inside and outside the sphere were 0.93 ± 0.25 mm and 0.95 ± 0.30 mm, respectively. The most deviated points outside the spheres were mainly distributed at the distolingual cusps of the mandibular second permanent molars (31.37%), while those inside the spheres were mainly distributed at the mesiolingual cusps of the mandibular first permanent molars (45.10%).ConclusionsThe radius of Monson’s sphere in Chinese young adult females was smaller than the classic four-inch value suggested by Monson. Deviation was observed from all selected points to their Monson’s sphere surface, with the most deviated points distributed primarily in the molar region.

Managing the Open Abdomen: Selecting an Appropriate Treatment Strategy.

Significance: The laparotomy is a common surgical procedure with a wide range of indications. Ideally, once the goals of surgery were achieved, the incision edges could then be approximated and the abdomen primarily closed. However, in some circumstances, it may be impossible to achieve primary closure, and instead the abdomen is intentionally left open. This review discusses the indications and objectives for the open abdomen (OA), summarizes the most common techniques for temporary abdominal closure, and illustrates treatment algorithms grounded in the current recommendations from specialty experts. Recent Advances: Still a relatively young technique, multiple strategies, and technologies have emerged to manage the OA. So too have the recommendations evolved, based on updated classifications that take wound characteristics into account. Recent studies have also brought greater clarity on recommendations for managing infection and malnutrition to support improved clinical outcomes. Critical Issues: The status of the OA can change rapidly depending on the patient's condition, the wound quality, and many other factors. Thus, there is a significant need for comprehensive treatment strategies that can be adapted to these developing circumstances. Future Directions: Treatment recommendations should be continuously updated as new technologies are introduced and old techniques fall out of use.

Comparative Evaluation of the Marginal Fit and Internal Adaptation of Polymethyl Methacrylate Interim Crowns Fabricated using two different techniques- “Conventional” and “CAD-CAM Milling”: An In Vitro Study

Introduction Interim crowns provide valuable functional and esthetic information of the final outcome during the evaluation period and act as the blueprint for the design of definitive prostheses. The fabrication technique and material used are the key factors involved in the success of the prosthesis. However, marginal fit and internal adaptation of Polymethyl Methacrylate (PMMA) interim crowns fabricated using conventional and computer aided designing-computer aided machining (CAD-CAM) PMMA milling have not been well investigated. The inter-group statistical comparison of means of normally distributed continuous variables is done using independent sample t test. Material and Methods Typodont (Nissin, Japan) of the maxillary central incisor was scanned (Ceramill Map 600+, Amann Girrbach AG) and 3D printed (Form 4, Formlabs) to create the master die used in the study, while a Typodont of a prepared maxillary central incisor was scanned using a digital scanner (Ceramill Map 600+, Amann Girrbach AG) and a .STL file obtained was modified using Exocad software for designing the study models. Three equidistant points A, B and C passing from the center of the incisal edge to the root of the typodont were indented labially and A` B` and C` were indented palatally in the same plane using Exocad software for symmetrical sectioning while checking for marginal fit and internal adaptation. 50 3D printed (Form 4, Formlabs India) models of the prepared tooth were printed and 25 interim crowns were fabricated using Polymethyl Methacrylate (DPI Tooth moulding material, DPI India) by conventional and 25 interim crowns were fabricated using CAD-CAM PMMA (Ceramill a-temp, Amann Girrbach AG). They were then luted (Han Temp Cement eugenol free, NE Korea) to respective models and viewed under a stereomicroscope (Ziess) for marginal fit at 2 specific points and internal adaptation at 4 specific points. Results The mean SD of marginal fit measurements at buccal and site in Group A (conventional technique) and Group B (CAD-CAM milling) was 95.32 ± 7.78 µm and 66.92 ± 14.59 µm respectively. At lingual site in Group A and Group B was 94.84 ± 7.97 µm and 66.80 ± 10.93 µm respectively. The mean marginal fit measurement at lingual site is significantly higher in Group A compared to Group B (P-value%3C0.05). The mean SD of internal fit measurements at upper 1 site in Group A and Group B was 335.19 ± 94.70 µm and 226.76 ± 89.68 µm respectively. At upper 2 site in Group A and Group B was 368.88 ± 120.25 µm and 240.85 ± 93.72 µm respectively. At lower 1 site in Group A and Group B was 313.52 ± 99.92 µm and 262.49 ± 94.33 µm respectively. At lower 2 site in Group A and Group B was 367.93 ± 107.36 µm and 264.52 ± 86.97 µm respectively. The mean internal fit measurement is significantly higher in Group A compared to Group B (P-value%3C0.05). Conclusion The interim crowns fabricated using the conventional technique displayed a less favourable marginal fit and internal adaptation when compared to CAD-CAM fabricated interim crowns. Key Words CAD-CAM, Interim crowns, Marginal fit and internal adaptation

In vitro evaluation of the accuracy of electronic apex locators and cone-beam CT in the detection of oblique root fractures.

This study aimed to compare the accuracy of cone-beam CT (CBCT) scanning and 3 different electronic apex locators (EALs) in the detection of simulated oblique root fractures (ORF) in different localizations. The study utilised a total of 80 human maxillary incisors, which were categorised into two groups based on the location of the ORF (apical and middle third of the root) formed on the buccal side of the root surface. The measurement of the distance between the incisal edge and the intersection of the ORF with the root canal was conducted using a stereomicroscope. This measurement is referred to as the actual working length (AWL). Additionally, three EALs-Dentaport ZX, EndoRadar Pro, and Propex II-were utilised to determine the electronic working length (EWL). Furthermore, CBCT images were employed to assess the distance, known as the CBCT working length (CWL). The differences were determined by subtracting AWL from EWL and CWL. Based on the accuracy of the devices, there were no significant differences observed among Dentaport ZX, EndoRadar, Propex II, and CBCT measures in both the apical and middle third ORF groups, within the acceptable range of 0.5 and 1 mm. The accuracy of Dentaport ZX, Propex II, and CBCT was higher in the middle third ORF group compared to the apical third ORF group, with a tolerance of 0.5 mm. However, there were no significant differences seen among the devices.

Methodology for vNOTES Sacrocolpopexy with Transvaginal Mesh Retroperitonealization and Tensioning

Background: Laparoscopy has the potential of making procedures less invasive with a lower complication profile while being more appealing to patients due to ease of recovery and cosmesis. Sacrocolpopexy has traditionally been performed through the abdominal route with limited reports of transvaginal applications. Methods: Our study aims to provide a step-by-step approach to performing a vNOTES sacrocolpopexy with appropriate tensioning and peritoneal coverage of the mesh used based on both cadaveric and live patient experience. This systematic description of a fully laparoscopic transvaginal apical suspension with mesh attachment to the sacrum being completely retroperitoneal and the mesh retroperitoneal and covered at the conclusion of the case. Results: Successful vNOTES Sacrocolpopexy is performed and reproduced, with transvaginal complete peritoneal coverage and tensioning of the mesh. Total vaginal length (TVL) of 9 cm in both live and cadaveric patients. The steps of the procedure include 1. A vNOTES laparoscopic-assisted vaginal hysterectomy is completed. 2. A 0-Prolene suture is attached longitudinally to the sacral arm of a precut (Y) mesh or any single layer Type I polypropylene mesh piece, placed from the sacral arm to the distal edge of the mesh forming a “U” shape with the bottom of the “U” ultimately attaching to the anterior longitudinal ligament. 3. To begin the SCP procedure after completion of the vaginal hysterectomy, dissection of the presacral mesh attachment site begins by entering the retroperitoneal space, slightly right of midline at the level of the ischial spine, lateral to the rectum and medial to the uterosacral ligament. 4. Once the dissection is completed with appropriate exposure of the anterior longitudinal ligament at the sacral promontory, the sacral mesh is attached to the anterior longitudinal ligament at the S1-2 level, ideally with a tacker under direct visualization. 5. Two sutures, one on each side of the tunnel, are placed on the cephalad edge of the sacral peritoneal incision and labeled. After removing the Gelport, two more absorbable sutures are attached to the anterior peritoneum of the anterior vaginal wall in the proximity of the bladder, around 3 cm on each side of the midline. These peritoneal sutures in each of the above two steps will later be tied together to help cover the arms of the mesh. 6. Before mesh arm attachment, each area on the anterior and posterior vaginal walls is dissected off respective tissue (bladder and perineal body/rectovaginal fascia) and then everted for mesh attachment. 7. Both anterior and posterior mesh pieces are sutured to their respective vaginal walls with six interrupted sutures. Each mesh arm will have several centimeters of mesh freely hanging off both anterior and posterior cuff edges. These edges can be trimmed to 2 cm past the vaginal cuff edge. 8. All three pieces of mesh are stacked together and serially threaded from anterior mesh to posterior mesh, ensuring each mesh piece remains aligned (Figure 1). Each U suture is then passed through the free ends of the anterior and posterior mesh pieces and then secured with a hemostat. The cut edges of the suture can either be aligned at the back of the posterior arm to permit retroperitonealization of the knot or placement at the vaginal apex abutting the vaginal cuff. 9. Peritoneal closure is achieved by tying a posterior tunnel suture to each respective anterior vaginal wall suture at each lateral edge of the tunnel incision. 10. The vaginal cuff closure begins with a Vicryl suture anchored at the patient’s right forniceal edge running it to midline while anchoring another suture at the left forniceal edge to permit the surgeon to tension the vaginal apex appropriately. 11. Mesh tensioning is achieved by placing a single digit through the remaining space left in the tunnel incision. A knot using the Prolene suture securing the overlapping mesh is tied extracorporeally and pushed through the vaginal cuff to mobilize the mesh crux cephalad, thus elevating the vaginal apex towards the sacrum. The elevation of this knot guides the vaginal length. 12. The remainder of the vaginal cuff is then closed while avoiding incorporation of the mesh into the suture line (the ideal distance from mesh Y-junction to cuff is 1-2cm). Conclusion: By describing an innovative and reproducible technique to perform vNOTES sacrocolpopexy based on cadaveric and live patient experience, we successfully demonstrate how to perform a laparoscopic transvaginal apical suspension with mesh attachment to the sacrum through retroperitoneal placement. The vNOTES approach for sacrocolpopexy may offer a viable alternative to the transabdominal approach for candidates with difficult transabdominal access while avoiding trocar injuries and reducing surgical costs.

Effect of the Height of a 3D-Printed Model on the Force Transmission and Thickness of Thermoformed Orthodontic Aligners.

This research aims to investigate the influence of model height employed in the deep drawing of orthodontic aligner sheets on force transmission and aligner thickness. Forty aligner sheets (Zendura FLX) were thermoformed over four models of varying heights (15, 20, 25, and 30 mm). Normal contact force generated on the facial surface of the upper right central incisor (Tooth 11) was measured using pressure-sensitive films. Aligner thickness around Tooth 11 was measured at five points. A digital caliper and a micro-computed tomography (µ-CT) were employed for thickness measurements. The normal contact force exhibited an uneven distribution across the facial surface of Tooth 11. Model 15 displayed the highest force (88.9 ± 23.2 N), while Model 30 exhibited the lowest (45.7 ± 15.8 N). The force distribution was more favorable for bodily movement with Model 15. Thickness measurements revealed substantial thinning of the aligner after thermoforming. This thinning was most pronounced at the incisal edge (50% of the original thickness) and least at the gingivo-facial part (85%). Additionally, there was a progressive reduction in aligner thickness with increasing model height, which was most significant on the facial tooth surfaces. We conclude that the thermoplastic aligner sheets undergo substantial thinning during the thermoforming process, which becomes more pronounced as the height of the model increases. As a result, there is a decrease in both overall and localized force transmission, which could lead to increased tipping by the aligner and a diminished ability to achieve bodily movement.

Evaluation of Mesiodistal Angulation of Maxillary Anterior Teeth in Incisal View Using Manual and Digital Methods: An In Vivo Study.

The aim of the present research was to assess the mesiodistal angulation of the maxillary anterior teeth utilizing Image J computer software, a Profile projector, and a Custom-made jig. A total of 34 subjects (17 males and 17 females) were chosen from a group of 18-30 years old with bilateral Angle Class I molars and canine relationships. One manual approach (Custom-made jig) and two digital methods (J computer software, a Profile projector) were used to record the mesiodistal angulation in incisal view. The individuals had alginate impressions made, and a facebow was used to capture the maxilla's spatial relationship with the cranium. The articulated cast with the help of mounting ring moved to the specially customized jig, then the angulations was measured in the incisal view after the casts were placed in a semi-adjustable articulator. Data were recorded and statistically analyzed. The mesiodistal angulation in the incisal view via three methods between the 17 males and 17 females has statistically significant different. Although the mesiodistal angulation for maxillary lateral incisor and canine did not show any statistically significant difference, the maximum and minimum values obtained were always greater in males in comparison with the females. This indicates that the positions of six maxillary anterior teeth in the males resulted in the creation of upward sweep of incisal edges of central and lateral incisors which was also referred to as "smiling line" producing masculine surface anatomy more squared and vigorous while feminine surface anatomy being more rounded, soft, and pleasant. There was no statistically significant difference between the right and left sides, indicating bilateral arch symmetry and the symmetrical place of the right teeth compared with the left side's corresponding teeth. On conclusion, according to the current study's findings, all three approaches can measure the mesiodistal angulations of maxillary anterior teeth in incisal view with clinically acceptable accuracy. The digital methods, which included using the Image J computer software and the profile projector, achieved more accurate results than the manual method. The outcomes of this study's mesiodistal angulations can be used as a reference for placing teeth in both fully and partially edentulous conditions. This study contributes to a better understanding of the importance of achieving the ideal occlusion in the Indian population by placing the maxillary anterior teeth at the proper mesiodistal angulation. How to cite this article: Shadaksharappa SH, Lahiri B, Kamath AG, et al. Evaluation of Mesiodistal Angulation of Maxillary Anterior Teeth in Incisal View Using Manual and Digital Methods: An In Vivo Study. J Contemp Dent Pract 2024;25(4):320-325.

Clinical implications of amathematical-geometrical model to predict changes in the anterior arch dimension.

Anterior arch length (AL) and the alterations in its dimension following incisor movements were shown to be predictable for an individual patient using amathematical-geometrical model based on athird-degree parabola. Although the model has been validated previously, it is hard to apply in daily orthodontic routine. Thus, the aim of this study was to modify the model using different approaches to allow its establishment in daily routine. This retrospective study was based on astudy collective, which was described previously and consisted of 50randomly chosen dental casts and lateral cephalograms taken before (T0) and after (T1) orthodontic treatment with fixed appliances. AJAVA computer program (Oracle, Austin, TX, USA) was developed to predict AL changes following therapeutic changes of arch width, depth or incisor inclination/position, taking the type of tooth movement into account. Performing exemplary AL calculations with the computer program, general rules and nomograms were set up, followed by multiple linear regression analyses to establish easy-to-use regression equations. The JAVA computer program is available for download. Sagittal changes showed more effect on AL than transverse modifications. Protruding incisors increased AL, but also reduced overbite. The extent of alteration in AL depended on the initial depth, width, incisor inclination, tooth movement type and distance between the incisal edge and the centre of rotation. The computer program precisely predicts individual changes in AL but is time-consuming. The presented regression equations and nomograms, considering metric variables, are easier to apply clinically and the differences compared to the AL calculated by the computer program are negligible.

Dental implant and abutment in PEEK: stress assessment in single crown retainers on anterior region.

Stress distribution assessment by finite elements analysis in poly(etheretherketone) (PEEK) implant and abutment as retainers of single crowns in the anterior region. Five 3D models were created, varying implant/abutment manufacturing materials: titanium (Ti), zirconia (Zr), pure PEEK (PEEKp), carbon fiber-reinforced PEEK (PEEKc), glass fiber-reinforced PEEK (PEEKg). A 50N load was applied 30o off-axis at the incisal edge of the upper central incisor. The Von Mises stress (σvM) was evaluated on abutment, implant/screw, and minimum principal stress (σmin) and maximum shear stress (τmax) for cortical and cancellous bone. The abutment σvM lowest stress was observed in PEEKp group, being 70% lower than Ti and 74% than Zr. On the implant, PEEKp reduced 68% compared to Ti and a 71% to Zr. In the abutment screws, an increase of at least 33% was found in PEEKc compared to Ti, and of at least 81% to Zr. For cortical bone, the highest τmax values were in the PEEKp group, and a slight increase in stress was observed compared to all PEEK groups with Ti and Zr. For σmin, the highest stress was found in the PEEKc. Stress increased at least 7% in cancellous bone for all PEEK groups. Abutments and implants made by PEEKc concentrate less σvM stress, transmitting greater stress to the cortical and medullary bone. The best stress distribution in PEEKc components may contribute to decreased stress shielding; in vitro and in vivo research is recommended to investigate this.

Stress distribution in endodontically treated external cervical resorption lesions restored with MTA and biodentine – A finite element analysis

IntroductionRoot resorption poses a significant challenge in dental practice, with external cervical resorption (ECR) being a common manifestation. ECR is often asymptomatic until advanced stages, complicating its diagnosis and management. Various factors contribute to its etiology, ranging from trauma to orthodontic treatment. The classification system proposed by Patel et al. (2018) offers a comprehensive framework for characterizing ECR lesions based on location and extent. Treatment strategies for ECR involve a combination of endodontic intervention and restorative techniques, with bioactive materials like mineral trioxide aggregate (MTA) and Biodentine emerging as promising options. However, the biomechanical behavior of teeth restored with these materials in the context of ECR remains underexplored. Materials and methodsThis study utilized finite element analysis (FEA) to assess stress distribution in teeth with simulated ECR lesions of varying sizes and locations, restored with MTA or Biodentine. Three-dimensional models of maxillary central incisors were generated based on CBCT scans, incorporating periodontal ligament and surrounding bone structures. Eight experimental models representing different ECR configurations were created and subjected to FEA using Optistruct software based on dimensional classification given by Patel et al., in 2018, A70 M & A70B: 1Ap, A130 M & A130B: 1Bp, B70 M & B70B: 2Ap, B130 M & B130B: 2Bp. All the models were tested for stress distribution by restoring the lesions with either M: MTA or B: Biodentine. Oblique load of 100 N was applied at 45°angle to the long axis 2 mm lingual to incisal edge. vonMises Stress distribution in enamel, dentine, restoration and at all the interfaces were observed. ResultsThe analysis revealed that both MTA and Biodentine restorations exhibited uniform stress distribution around ECR lesions, with no significant differences based on lesion location or size. Maximum stress concentrations were observed around the restorations, particularly in subcrestal lesions. However, overall stress levels were comparable between MTA and Biodentine restorations, indicating similar biomechanical performance. ConclusionFinite element analysis provides valuable insights into the biomechanical behavior of teeth with ECR lesions restored with MTA and Biodentine. Both materials exhibit similar stress distribution patterns and offer adequate reinforcement against mechanical forces. Clinicians can confidently utilize MTA or Biodentine in the management of ECR, considering their favorable biomechanical properties and clinical outcomes. Further research is necessary to validate these findings and optimize treatment protocols for ECR.

Obesity, Pocrescophobia and Oral Health.

Oral health plays a crucial role in obesity management. Scientific evidence suggests an association between obesity and oral diseases, including periodontal disease, dental caries, tooth erosion, xerostomia, and dentinal hypersensitivity. Maintaining optimal oral health is essential for obese patients, as compromised dentition or oral discomfort can influence dietary habits. However, managing oral health in obese individuals can be challenging due to anatomical limitations and lifestyle choices. Profound knowledge of obesity and its manifestations, the oral health professionals need to raise awareness and provide patients with comprehensive care. Pocrescophobia also known as obesophobia, is an intense fear of gaining weight. It affects both adoloscent women and men, manifesting as an irrational dread associated with weight gain. Like other phobias, obesophobia falls under the umbrella of anxiety disrders, leading to exaggerated anxiety when discussing or thinking about weight gain. Individuals with this fear may go to extreme lengths to avoid weight gain, which can increase the risk of developing eating disorders. Stress can lead to bruxism, wears away the occlusal surfaces and incisal edges, resulting in flat, shorter teeth. Smooth V-shaped cavities arise when lateral stresses surpass physiological limitations, resulting in gum recession and tooth discomfort. Canker sores, xerostomia, and lichen planus have all been linked to stress. By addressing both obesophobia and obesity as well as oral health, patients' overall well-being and quality of life can be improved.

Effect of maxillary distraction osteogenesis and LeFort-1 advancement orthognathic surgery on soft-tissue thickness and anterior soft-tissue to hard-tissue movement ratios among patients with complete unilateral cleft lip and palate

Objectives: The objective of this study was to compare the soft-tissue thickness and anterior soft-tissue to hard-tissue movement ratios in patients with unilateral cleft lip and/or palate (UCLP) following maxillary distraction osteogenesis using rigid external distractor device and maxillary advancement at LeFort I level using lateral cephalograms. Material and Methods: This retrospective study was conducted on 20 patients with UCLP who underwent either LeFort I maxillary advancement or maxillary distraction osteogenesis. Non-syndromic patients with complete UCLP anomalies and skeletal class III patterns due to maxillary hypoplasia were included in the study. The patients with a pre-surgical negative overjet of ≥5 mm were treated by maxillary distraction osteogenesis, while a negative overjet of &lt;5 mm was managed with maxillary advancement orthognathic surgery. The growth completion in all the patients was assessed using the cervical vertebrae maturation index (CS 6) on a lateral cephalogram. The lateral cephalograms taken before surgery at (T0) and after a minimum interval of six months (T1) of surgery were assessed for changes in soft-tissue thickness and hard-tissue to soft-tissue movement ratios among the two groups. Paired t-test was used to compare the mean values obtained within the same group at two different time intervals. Unpaired t-test was used to compare mean values between the Groups 1 and 2. Pearson’s correlation coefficient (r) test was used to assess the associations between the mean changes in hard- and soft-tissue variables. Results: Group 1 showed significantly greater maxillary advancement compared to Group 2 with a mean difference of 5.80 mm at Point A and 7.65 mm at the upper incisal edge. Soft-tissue thickness decreased significantly after advancement in Group 1 at subnasale (P &lt; 0.05), labrale superius, stomion, and labrale inferius (P &lt; 0.01) and at subnasale (P &lt; 0.05), stomion and labrale inferius (P &lt; 0.01) in Group 2. There was a significantly strong correlation between the hard- and soft-tissue movement in sagittal plane in both Group 1 and Group 2. In Groups 1 and 2, a statistical highly significant strong positive correlation was found between vertical change in dU1 to soft-tissue dLs and dStms. In Group 2, a statistical highly significant strong positive correlation was found between vertical change in dA to soft-tissue dC and dStms. Conclusion: The soft-tissue thickness reduced in patients with UCLP after maxillary advancement in both groups. The soft tissue followed the hard tissue in both groups. There was a greater downward movement of the maxillary base and soft-tissue lengthening in Group 1 compared to Group 2.