3D evaluation of sagittal inclination of the maxillary dentition in relation to facial landmarks: A cohort study.

BACKGROUND: The determination of the maxillary occlusal plane presents a significant clinical challenge in the treatment of edentulous patients as well as it is critical for complex full-mouth reconstructions in dentate patients, including those with implant-supported rehabilitations. While the use of a Fox plane plate is standard in edentulous cases, its application in dentate patients lacks thorough documentation in existing literature. PURPOSE: This clinical study assessed the sagittal position of the maxillary dentition in relation to facial landmarks using a digital three-dimensional analysis and evaluated the suitability and reliability of applying a simulated Fox plane plate, also known as an occlusal plane guide, in dentate patients. MATERIALS AND METHODS: Eighty-one subjects were recruited at the Department of Prosthetic Dentistry of Goethe University Frankfurt, Germany, according to specific inclusion criteria. Intraoral and facial scans were obtained and analyzed using GOM Inspect Pro software (GOM, Braunschweig, Germany). The angles between the maxillary occlusal plane and three variations each of Camper's plane and ala-tragus line, relating to superior, middle, and inferior tragus points, were measured. These modified planes were then compared to a plane established by a simulated digital Fox plane plate, which was adapted to the maxillary anterior teeth and the lowest point of the posterior teeth in both quadrants. RESULTS: A total of 81 subjects (58 female and 23 male) with a mean age of 23.9 years were evaluated in this study. No significant angular difference was found between the angles of the maxillary occlusal plane compared with superior Camper's plane, middle Camper's plane, or superior ala-tragus line (p >0.05). The smallest angle occurred between superior Camper's plane and the maxillary occlusal plane on both the right (3.443°) and left (3.535°) sides. The application of a Fox plane plate resulted in two different occlusal planes in 70% of patients, significantly deviating from the digitally determined plane (p <0.05). CONCLUSION: Superior and middle Camper's planes, along with superior ala-tragus line, can be considered approximately parallel reference planes and are suitable for routine determining of the maxillary occlusal plane in restorative treatments. However, in contrast to digital evaluation methods, the application of a Fox plane plate in dentate patients showed high variability, indicating its low reproducibility due to its ambiguous positioning on the maxillary dentition. Clinical trial registration site: https://drks.de/search/de/trial/DRKS00030166.

Orthodontic camouflage treatment of a hyperdivergent adolescent patient with anterior open bite and TMD: a case report.

BACKGROUND: In orthodontics, anterior open bite is a common malocclusion that recurs frequently. Because the causes of anterior open bite are so varied, medical professionals must create customized treatment programs for each patient based on their unique etiology. Through the lowering of the posterior teeth, closure of the anterior teeth gap, and cooperation with intermaxillary traction, the treatment plan outlined in this case study sought to achieve a stable occlusion. CASE PRESENTATION: This case report aims to describe an orthodontic camouflage treatment of a 15-year-old female patient with anterior open bite, arch width discrepancy and a history of temporomandibular joint disorder. The patient was treated with intermaxillary vertical elastics and the multiple edgewise arch wire (MEAW) approach. A satisfactory occlusion with a neutral molar relationship was attained after 29 months of orthodontic therapy. The condylography recording showed that this patient's occlusion tended to be more stable both before and after our treatment. The purpose of this case study is to provide an overview of an orthodontic camouflage treatment for a female patient, who had a history of temporomandibular joint disease, anterior open bite, and arch width disparity. CONCLUSIONS: Our results demonstrated that more attention should be paid to levelling the occlusal plane, intrusion of the molars, decompression of temporomandibular joints and the etiology factors of malocclusion during the orthodontic period for those patients with anterior open bite.

Use of Adult Dry Human Mandibles to Study of Mandibular Foramen from Various Bony Landmarks.

Background: Precise knowledge of the mandibular foramen's location is essential for clinical and surgical procedures, especially the inferior alveolar nerve block. Variability in its position concerning different bony landmarks can significantly impact clinical outcomes. Materials and Methods: This study examined 30 Adult dry human mandibles to determine the mandibular foramen's positions in relation to specific bony landmarks: the occlusal plane, posterior border of the ramus, and lingula. Measurements were obtained using a calibrated digital caliper, and statistical analysis was performed. Results: The study revealed significant variations in the position of the mandibular foramen. In relation to the occlusal plane, the mandibular foramen was found at an average height of approximately 15.2 mm (±2.1 mm). Regarding the posterior border of the ramus, it was situated at an average distance of about 18.5 mm (±3.4 mm). In relation to the lingula, the average distance was approximately 21.8 mm (±4.0 mm). These results underscore the considerable individual differences and anatomical variations in the mandibular foramen's location among the studied specimens. Conclusion: The observed variations in the position of the mandibular foramen emphasize the need for clinicians and surgeons to be cognizant of these differences when performing procedures involving the inferior alveolar nerve block. Understanding these anatomical variations is crucial for enhancing clinical precision, reducing complications, and ensuring optimal outcomes.

Clinical evaluation on the use of a new accessory device for Fox plane.

OBJECTIVE: Evaluate the assimilation capacity and ease of handling of the Fox plane accessory by dentistry students, through a questionnaire about the experience in using this device compared to the conventional one. Its intention is to minimize possible interpretation errors and challenges that the traditional method determines. METHODS: After approval by the Research Ethics Committee, registration at Sistema Nacional de Informações sobre Ética em Pesquisa/National Information System on Research Ethics (SISNEP) and signing of the free and informed consent form, 51 undergraduate students treating patients in need of complete dentures at Instituto de Ciência e Tecnologia/Institute of Science and Technology (ICT) Unesp in São José dos Campos completed a questionnaire to evaluate the technical ease of use and provider acceptance. The obtained data were submitted to statistical analysis, evaluating technical ease and acceptance by operators. RESULTS: The results were analyzed using descriptive and inferential statistics using the Jamovi 2.2.5 software. From the responses, the frequency was obtained for each question in the questionnaire, then the weighted mean was calculated, average rating and percentage. With the results of these analyses it was possible to measure the level of satisfaction of the participants in relation to the use of the device. CONCLUSION: It was concluded that most students have difficulty using the conventional Fox plane and that the accessory facilitated the process of determining the superior orientation plane, and its ease of use.

The location of mandibular foramen relative to the occlusal plane: a study on anatolian dry mandible.

Purpose: The study aims to evaluate the location of mandibular foramen (MF) with respect to the occlusal plane (OP) and its location on the ramus using Anatolian dry mandibles. Materials and methods: A total of 115 dry mandibles with mandibular molars were analyzed. The distance between the MF and the OP was examined with a flat metal plate. Group A was above the OP; group L was at level, and group B was below the OP. The distances between the MF and anterior border (A-MF), sigmoid notch (U-MF), posterior border (P-MF), and lower border (L-MF) were measured. The symmetry between the two sides was examined. Pearson chi-square and Student's t-test were performed for statistical analysis. Results: According to the analysis, 50.23% of MF was located below the OP (p<0.05). The mean distances of Groups A and B were 3.45 and 4.78 mm, respectively. There was no difference between the left and right in groups (p>0.05). The distance A-MF was 14.71 mm. There was no statistical difference between the distances A-MF and P-MF or U-MF and L-MF. Conclusion: Half of the MF (50.23%) was located below the occlusal plane with a mean distance of 4.78 mm. It may be helpful to place the needle 3-4 mm above the OP and 1.5-2 mm back of the anterior border to obtain a successful inferior alveolar nerve block. The MF was located at the center of the medial surface of the ramus.

Assessing the impact of occlusal plane rotation on facial aesthetics in orthodontic treatment: a machine learning approach.

BACKGROUND: Adequate occlusal plane (OP) rotation through orthodontic therapy enables satisfying profile improvements for patients who are disturbed by their maxillomandibular imbalance but reluctant to surgery. The study aims to quantify profile improvements that OP rotation could produce in orthodontic treatment and whether the efficacy differs among skeletal types via machine learning. MATERIALS AND METHODS: Cephalometric radiographs of 903 patients were marked and analyzed by trained orthodontists with assistance of Uceph, a commercial software which use artificial intelligence to perform the cephalometrics analysis. Back-propagation artificial neural network (BP-ANN) models were then trained based on collected samples to fit the relationship among maxillomandibular structural indicators, SN-OP and P-A Face Height ratio (FHR), Facial Angle (FA). After corroborating the precision and reliability of the models by T-test and Bland-Altman analysis, simulation strategy and matrix computation were combined to predict the consequent changes of FHR, FA to OP rotation. Linear regression and statistical approaches were then applied for coefficient calculation and differences comparison. RESULTS: The regression scores calculating the similarity between predicted and true values reached 0.916 and 0.908 in FHR, FA models respectively, and almost all pairs were in 95% CI of Bland-Altman analysis, confirming the effectiveness of our models. Matrix simulation was used to ascertain the efficacy of OP control in aesthetic improvements. Intriguingly, though FHR change rate appeared to be constant across groups, in FA models, hypodivergent group displayed more sensitive changes to SN-OP than normodivergent, hypodivergent group, and Class III group significantly showed larger changes than Class I and II. CONCLUSIONS: Rotation of OP could yield differently to facial aesthetic improvements as more efficient in hypodivergent groups vertically and Class III groups sagittally.

Comparison of mesiodistal angulations of premolars and molars in anterior open bite subjects with different sagittal malocclusions: A retrospective study.

INTRODUCTION: Mesiodistal angulation of premolars and molars can be altered by forces of open bite malocclusion. The aim of this study was to compare the mesiodistal angulations of the posterior teeth in class I, II, and III individuals with anterior open bite (AOB) versus individuals with harmonious occlusion. METHODS: This comparative cross-sectional study used 299 lateral head radiographs of individuals with permanent dentition. There were 4 groups (harmonious occlusion [n=89], Class I open bite [OB] [n=75], Class II OB [n=66], and Class III OB [n=69]). Premolar (1UPM, 2UPM) and molar (1UM, 2UM) angulations were measured relative to the occlusal plane and the palatal or mandibular plane by a trained and calibrated evaluator. ANOVA and Scheffe tests were used for statistical analyses (P<0.05). RESULTS: The mesial angulation of the upper premolars showed greater angulation of between approximately 2° and 5° in the OB groups compared to the harmonious occlusion group (P<0.05). Only in the Class II OB group did the first and second upper molars show distal angulation in relation to the palatal plane (1UM 81.85°±5.42°; 2UM 75.32±7.4°) (P<0.05). The Class III OB group presented the greatest distal angulations of the lower premolars and molars (between 3° to 5° of difference, P<0.05) in relation to those of the harmonious occlusion group. CONCLUSIONS: The upper first premolars in all the AOB groups and the lower second premolars in the Class II OB group had greater mesioangulation. Additionally, the upper molars of the Class II OB group and the lower molars of the Class III OB group showed distoangulation compared with the molars in the group with harmonious occlusion.

Surgical Control of the Pitch, Roll and Yaw in the Maxillary Arch: A Technical Note.

The adequate three-dimensional location of the maxilla is one of the main objectives in orthognathic surgery. We propose an instrument manufactured from a Fox Plane (FP) modified with red light in the shape of a cross and a bubble level, in which we perform an occlusal registration for the trans-surgical control of the three-dimensional position of the maxilla, By adding an occlusal registration to the FP, the occlusal plane is transferred and amplified to an extraoral reference. The red light in the shape of a cross allows us to assess the success of our movements more accurately.

Biomechanically and Periodontally-Based Orthodontic Treatment of a Patient with Upper Canine Affected by External Cervical Resorption (ECR): A Case Report.

(1) Background: Orthodontic treatment may be a potential predisposing factor for ECR. The affected tooth goes to ankylosis, which could lead to a malocclusion. Although teeth severely affected by ECR (class IV Heithersay) are usually extracted, this case report aims to present the use of an ECR class IV upper canine, both as ankylosed to solve the malocclusion and the occlusal plane canting, as well as not ankylosed to correct its ridge defect with orthodontic extrusion. (2) Methods: A 14-year-old male, complaining of an ugly smile and a failed orthodontic attempt to recover an impacted canine, was referred to the orthodontic clinic. He was diagnosed with class II right subdivision, midline deviation, both upper and lower occlusal plane canting, and an upper left canine, previously impacted, showing ECR class IV. The treatment first included canting resolution with a cantilever and a spring, exploiting the anchorage offered by the ankylosed ECR canine. Then, a coronectomy, endodontic treatment, and orthodontic extrusion of that canine were performed to obtain the implant site development. (3) Results: Clinical and radiographic outcomes showed normocclusion and better bony conditions for safer implant placement in the aesthetic zone. (4) Conclusions: The high aesthetics and the periodontal and bony conditions obtained are probably not achievable by other therapeutic alternatives.

Correlation of "K" plane to occlusal plane and three different ala-tragal lines in dentulous subjects with different skeletal forms: A cephalometric study.

Aim: Orientation of the occlusal plane is an important clinical procedure for complete denture fabrication. An attempt had been made to reconstruct the occlusal plane using a different reference plane. The aim of this study was to find the correlation of the "K" plane to the occlusal plane and to assess the angular deviation between the K-plane to the occlusal plane (KO) with different skeletal forms. Settings and Design: An in vivo observational study was conducted on dentulous subjects having Class I dental occlusion with different skeletal forms undergoing orthodontic treatment. Materials and Methods: The study was conducted on 54 subjects aged 18-30 years. Metallic balls (3 mm in diameter) were attached to the desired landmarks, and a lateral cephalogram was taken for each subject. Cephalometric analysis was done using the Dolphin Imaging software, and the values obtained were recorded and subjected to statistical analysis. Statistical Analysis Used: The values obtained were recorded and subjected to statistical analysis using simple descriptive analysis, Shapiro-Wilk test, Mann-Whitney U-test, and Pearson's correlation. Results: A positive correlation was found between KO with a mean angular deviation of 8.59° ± 3.05°. The angle was found to be steeper in skeletal Class II subjects. Conclusions: Clinical application of the K-plane to use as a reference plane to orient the posterior occlusal plane can enhance the treatment outcome for a removable prosthesis. The results of this study provide a theoretical foundation for the practical restoration of the occlusal plane in different skeletal forms.

In vitro comparison of the accuracy of an occlusal plane transfer method between facebow and POP bow systems in asymmetric ear position.

PURPOSE: This in vitro study aimed to compare the accuracy of the conventional facebow system and the newly developed POP (PNUD (Pusan National University Dental School) Occlusal Plane) bow system for occlusal plane transfer in asymmetric ear position. MATERIALS AND METHODS: Two dentists participated in this study, one was categorized as Experimenter 1 and the other as Experimenter 2 based on their clinical experience with the facebow (1F, 2F) and POP bow (1P, 2P) systems. The vertical height difference between the two ears of the phantom model was set to 3 mm. Experimenter 1 and Experimenter 2 performed the facebow and POP bow systems on the phantom model 10 times each, and the transfer accuracy was analyzed. The accuracy was evaluated by measuring the angle between the reference virtual plane (RVP) of the phantom model and the experimental virtual plane (EVP) of the upper mounting plate through digital superimposition. All data were statistically analyzed using a paired t-test (P < .05). RESULTS: Regardless of clinical experience, the POP bow system (0.53° ± 0.30 (1P) and 0.19° ± 0.18 (2P) for Experimenter 1 and 2, respectively) was significantly more accurate than the facebow system (1.88° ± 0.50 (1F) and 1.34° ± 0.25 (2F), respectively) in the frontal view (P < .05). In the sagittal view, no significant differences were found between the POP bow system (0.92° ± 0.50 (1P) and 0.73° ± 0.42 (2P) for Experimenter 1 and 2, respectively) and the facebow system (0.82° ± 0.49 (1F) and 0.60° ± 0.39 (2F), respectively), regardless of clinical experience (P > .05). CONCLUSION: In cases of asymmetric ear position, the POP bow system may transfer occlusal plane information more accurately than the facebow system in the frontal view, regardless of clinical experience.

Occlusal Plane Steepness and Profile Change Following TAD-Based One-Step Retraction on Four-Unit Extraction Cases: A Retrospective Study.

BACKGROUND: With the introduction of high-tech appliances, anchorage devices, and improved patient awareness of the risks associated with maxillofacial surgery, treating complex situations with orthodontic treatment has become more difficult in recent years. This study was conducted to demonstrate that orienting the occlusal plane, all the dental, skeletal, and soft tissue parameters, would be improved and to find which of these parameters could be correlated with the steepness of the occlusal plane. MATERIALS AND METHODS: This was a retrospective study including 40 cephalometric interpretations for patients who were planned for four-unit extractions (20 cephalometric radiographies before treatment and 20 after finishing the treatment). All were treated in the same orthodontic clinic with the same protocol using the McLaughlin-Bennett-Trevisi (MBT) prescription, with 22 slots and one-step retraction following four-unit extraction based on temporary anchorage devices (TADs). RESULTS: There was no significant change in the canting of the occlusal plane, and it remained relatively stable from 6.31° to 7.55°, while all the soft tissue-related cephalometric measurements were reduced significantly, except the nasolabial angle, as the relation of the upper and lower lip to the esthetic line of Ricketts' (E-Line) was reduced by 2.91 and 2.46°, respectively; furthermore, the angle of convexity was reduced from 10.92° to 9.79°. Besides, the upper incisor display was reduced by 0.38° Conclusions: Both the Frankfort mandibular angle and upper-incisor-to-Frankfort horizontal plane were significant parametric factors associated with profile change after extraction treatment having a positive 0.01-level Pearson association with occlusal plane steepness. Therefore, using the MBT prescription with TAD-based retraction is one of the favorable methods for the management of complex cases.

Implications of occlusal plane in diagnosis and treatment of malocclusion. / 平面对错 畸形诊断和治疗的意义.

Occlusal plane (OP) is one of the essential factors affecting craniofacial morphology and function. The OP not only assists in diagnosing malocclusion but also serves as an important reference for making treatment plans. Patients with different types of malocclusions have different forms of OP. Compared with patients with standard skeletal facial type, the occlusal plane of patients with skeletal class Ⅱ and high angle is steeper, while that of patients with skeletal class Ⅲ and low angle is more even. In orthodontic treatment, adjusting and controlling the OP can promote the normal growth and development of the mandible in most patients with malocclusion during the early stage of growth, while causing favorable rotation of the mandible in some adults with mild-to-moderate malocclusion. For moderate-to-severe malocclusion, the OP rotation by orthodontic-orthognathic treatment can achieve better long-term stability. This article reviews the evolution of the definition of OP and its implications for diagnosing and the guiding treatment of malocclusion.

Imaging study on the relationship between anterior and posterior occlusal planes and temporomandibular osteoarthrosis.

OBJECTIVES: The aim of this study was to compare the anterior and posterior occlusal plane characteristics of patients with different temporomandibular joint osseous statuses. METHODS: A total of 306 patients with initial cone beam CT (CBCT) and cephalograms were included. They were divided into three groups on the basis of their temporomandibular joint osseous status: bilateral normal (BN) group, indeterminate for osteoarthrosis (I) group, and osteoarthrosis (OA) group. The anterior and posterior occlusal planes (AOP and POP) of the different groups were compared. Then, the regression equation was established after adjusting for confounding factors, and a correlation analysis between the occlusion planes and other parameters was performed. RESULTS: SNA, SNB, FMA, SN-MP, Ar-Go, and S-Go were correlated with the occlusal planes. Relative to the BN and I groups, the FH-OP of the OA group increased by 1.67° on the average, FH-POP increased by 1.42° on the average, and FH-AOP increased by 2.05° on the average. CONCLUSIONS: The occlusal planes were steeper in the patients with temporomandibular osteoarthrosis than in the patients without it, and the mandible rotated downward and backward. The height of the mandibular ramus, the mandibular body length, and the posterior face height were small. In clinical practice, attention should be given to the potential risk of temporomandibular joint osteoarthrosis in such patients. In addition, SNB, FMA, SN-MP, Ar-Go, S-Go, and occlusal planes had moderate correlations.

The predictability of maxillary curve of Spee leveling with the Invisalign appliance.

OBJECTIVES: To evaluate the predictability of the Invisalign appliance (Align Technology, Santa Clara, Calif) in leveling the maxillary curve of Spee (COS). MATERIALS AND METHODS: A retrospective sample of adult subjects treated with the Invisalign appliance between 2013 and 2019 were selected. Patients were treated nonextraction in the maxillary arch and had either Angle Class I or II malocclusions with a minimum of 14 aligners with no bite ramps. Initial, predicted, and actual outcomes were analyzed with Geomagic Control X software (version 2017.0.3; 3D Systems, Cary, NC). RESULTS: A sample of 53 cases satisfied inclusion/exclusion criteria. Paired t-tests demonstrated a significant difference between mean predicted and actual maxillary COS leveling with a shortfall of 0.11 mm (SD = 0.37; P = .033). Planned intrusion tended to be more accurate posteriorly with an overexpression of 117% for the first molars. Planned extrusion was the least accurate, with the mid-arch demonstrating expressions of -14% to -48%. These teeth intruded despite a prescribed extrusive movement. CONCLUSIONS: The Invisalign appliance did not accurately predict maxillary COS leveling. Planned intrusive movements were overcorrected, and planned extrusive movements were either undercorrected or resulted in intrusion. This effect was most apparent for the upper first molar, which expressed 117% and -48% of planned intrusion and extrusion, respectively.

An Esthetic Approach for Rehabilitation of Long-Span Edentulous Arch Using Artificial Intelligence.

Successful full-mouth rehabilitation requires contemporary and advanced treatment planning, especially in distal extension cases. Multiple treatment modalities are available in those cases. Treatment outcome in these patients remains challenging. Though implants are one of the treatment options in such scenarios, fixed removable partial dentures with precision attachments are the best treatment options for patients who cannot afford expensive treatment. We have made an attempt to describe a case report of a long-span edentulous arch by incorporating the ideas and information received from Chat Generative Pre-trained Transformer (GPT).

Laser Indicated Occlusal Plane Device: A Novel Technique for Occlusal Plane Orientation.

Parallelism to the ala-tragus line is commonly used as a guide for the orientation of the occlusal plane with the help of a fox plane. The accuracy of parallelism is affected by improper judgment or patient movement. This report describes a method with a modified fox plane that aids in occlusal plane determination. The device is placed in the patient's mouth with the maxillary occlusal rim to determine parallelism to the ala-tragus line and interpupillary line. The adjustments are made until the laser light on the device runs parallel to the ala-tragus line, and the spirit bubble is centered between the lines of the tube. This technique facilitates direct visualization of parallelism, thereby avoiding parallax errors.

Relationship between the occlusal plane and three different levels of ala-tragus line in a sample of sudanese adults / Relación entre el plano oclusal y tres niveles diferentes de la línea ala-trago en una muestra de adultos sudaneses

Aim: Correct orientation of the occlusal plane plays a vital role in achieving the perfect occlusal balance and function of complete dentures. This study aimed to evaluate the most reliable posterior reference point of the ala-tragus line (ATL) concerning occlusal plane (OP) in a sample of the dentate Sudanese population. Materials and Methods: A total of 150 subjects with healthy and well-aligned permanent teeth were randomly selected. Right lateral profile photographs were taken with subjects having a fox plane placed intra-orally, contacting the occlusal plane. Reference points corresponding to inferior, middle, and superior borders of the tragus and inferior border of the ala of the nose were marked on photographs. The angles between the lines were measured using the Auto-CAD software program, and the most parallel relationship was determined. Descriptive statistics in terms of means and standard deviations were presented. Independent t-test and one-way ANOVA tests were used to compare as appropriate. A p-value < 0.05 was considered significant. Results: The mean angle formed by the OP and ATL was 8.5±3.69º for the superior level, 4.68±3.13º for the middle line, and 2.89±2.57º for the inferior line. A significant difference was found between the means of the three angles (p< 0.001), while no significant difference (p> 0.05) was found between both genders regarding the measured angles. Conclusions: The line joining the inferior border of the ala of the nose with the inferior border of the tragus of the ear was the most reliable line in terms of parallelism to determine the occlusal plane orientation.

Antecedentes: La orientación correcta del plano oclusal juega un papel vital para lograr el equilibrio oclusal perfecto y la función de las prótesis completas. Este estudio tuvo como objetivo evaluar el punto de referencia posterior más confiable de la línea ala-trago (ATL) con respecto al plano oclusal (OP) en una muestra de la población dentada de Sudán. Materiales y Métodos: Se seleccionaron aleatoriamente un total de 150 sujetos con dientes permanentes sanos y bien alineados. Se tomaron fotografías de perfil lateral derecho de sujetos a los que se les colocó un plano de zorro intraoralmente, en contacto con el plano oclusal. En las fotografías se marcaron los puntos de referencia correspondientes a los bordes inferior, medio y superior del trago y al borde inferior del ala de la nariz. Los ángulos entre las líneas se midieron utilizando el programa de software Auto-CAD y se determinó la relación más paralela. Se presentaron estadísticas descriptivas en términos de medias y desviaciones estándar. Se utilizaron prueba-t independiente y prueba ANOVA unidireccional para las comparaciones, según correspondiera. Se consideró significativo un valor de p<0,05. Resultados: El ángulo medio formado por OP y ATL fue de 8,5±3,69º para el nivel superior, 4,68±3,13º para la línea media y 2,89±2,57º para la línea inferior. Se encontró una diferencia significativa entre las medias de los tres ángulos (p< 0,001), mientras que no se encontró diferencia significativa (p>0,05) entre ambos sexos con respecto a los ángulos medidos. Conclusión: La línea que une el borde inferior del ala de la nariz con el borde inferior del trago de la oreja fue la línea más confiable en términos de paralelismo para determinar la orientación del plano oclusal.

Three-dimensional analysis of the relationship between mandibular retromolar space and positional traits of third molars in non-hyperdivergent adults.

BACKGROUND: The anatomical position of the mandibular third molars (M3s) is located in the distal-most portions of the molar area. In some previous literature, researchers evaluated the relationship between retromolar space (RS) and different classifications of M3 in three­dimensional (3D) cone-beam computed tomography (CBCT). METHODS: Two hundred six M3s from 103 patients were included. M3s were grouped according to four classification criteria: PG-A/B/C, PG-I/II/III, mesiodistal angle and buccolingual angle. 3D hard tissue models were reconstructed by CBCT digital imaging. RS was measured respectively by utilizing the fitting WALA ridge plane (WP) which was fitted by the least square method and the occlusal plane (OP) as reference planes. SPSS (version 26) was used to analyze the data. RESULTS: In all criteria evaluated, RS decreased steadily from the crown to the root (P < 0.05), the minimum was at the root tip. From PG-A classification, PG-B classification to PG-C classification and from PG-I classification, PG-II classification to PG-III classification, RS both appeared a diminishing tendency (P < 0.05). As the degree of mesial tilt decreased, RS appeared an increasing trend (P < 0.05). RS in classification criteria of buccolingual angle had no statistical difference (P > 0.05). CONCLUSIONS: RS was associated with positional classifications of the M3. In the clinic, RS can be evaluated by watching the Pell&Gregory classification and mesial angle of M3.

A Cephalometric Analysis Assessing the Validity of Camper's Plane to Establishing the Occlusal Plane in Edentulous Patients.

Complete denture fabrication requires multiple clinical and laboratory steps. One of the most critical clinical steps is establishing an anatomical occlusal plane based on hard and soft tissue references. The aim of this study was to determine whether age or gender affects the level of the Ala-Tragus plane to establish which reference point on the Tragus should be used when fabricating the occlusal plane in edentulous patients. Clinical photographs and lateral cephalometric radiographs with complete dentitions were taken from 58 volunteers at the DMD clinic at the University of Kentucky. Each photograph was superimposed over its corresponding cephalometric image. An analysis was conducted to establish the angle of the occlusal plane relative to the Ala-Tragus landmarks; this data was then grouped according to age and gender. The analysis shows that age and gender did not significantly affect where the Camper's plane should be approximated for complete denture treatment. However, it was found that the most parallel line to the occlusal plane was Ala's inferior border to the 'Tragus's inferior border. It should be noted that the volunteers' skeletal classification was significantly related to a Cl III malocclusion tendency. Still, with this new information, functionality and esthetics can be more adequately addressed for patients undergoing complete denture treatment. Given our results, we suggest redefining the 'Camper's plane with a line extending from 'Ala's inferior border to the 'Tragus's inferior border instead of the superior border. Further consideration should be taken if the patient is a skeletal CL III malocclusion.