The correlation analysis between incisal guidance angle and occlusal plane angles and temporomandibular joint morphology.

OBJECTIVES: The correlations between the incisal guidance angle (IGA) and occlusal plane angles and temporomandibular joint (TMJ) morphology were investigated in adults with skeletal Class II division II malocclusion. MATERIALS AND METHODS: CBCT images of 37 patients were analyzed. It included 19 cases of skeletal Class II division II malocclusion with low angle (study group) and 18 cases of skeletal Class I average angle (control group). The Invivo Dental 5 software was employed to acquire the data of the incisal guidance angle (IGA), occlusal plane angle (FH-OP), anterior occlusal plane angle (FH-AOP) and the TMJ measurement items. RESULTS: The results of IGA, FH-AOP angle and FH-OP angle showed the study group > the control group (P < 0.05). There were statistically difference in the condylar mediolateral diameters, articular eminence inclination and height, and posterior joint spaces between two groups. No differences were revealed in the condylar anteroposterior diameters, the condylar inclination angle, condylar head width and height, condylar length, glenoid fossa depth and width between two groups. In the study group, IGA showed a moderate correlation with FH-AOP, a weak correlation with FH-OP and condylar mediolateral diameters. Meanwhile, there was a correlation between FH-AOP, FH-OP, and TMJ indicators. CONCLUSIONS: The IGA was not only related to FH-AOP and FH-OP, but also to the condylar mediolateral diameters. In addition, there was a correlation between the occlusal plane angles and TMJ morphology in skeletal Class II division II low angle malocclusion. CLINICAL RELEVANCE: For patients with skeletal Class II division II low angle malocclusion, adjusting the IGA and the occlusal plane angles could improve the esthetic appearance of the anterior teeth, occlusal function, and TMJ morphology.

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.

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.

Effect of orthodontic treatment with premolar extractions on occlusal planes: A retrospective study.

OBJECTIVE: To figure out whether premolar extractions treatment would influence the cant of the occlusal planes and thus affect dentoskeletal patterns in patients with different types of malocclusions. MATERIALS AND METHODS: A total of 140 post-orthodontic treatment subjects (96 females, 44 males) were included in this study, and their lateral cephalograms and demographic information were collected and analysed. The patients were divided into extraction and non-extraction groups. The ANB, SNA, SNB, Wits, Facial Height Index (FHI), SN-MP, SN-AOP, SN-POP and AOP-POP angle were measured on the cephalograms. Other possible confounding factors were recorded. Data were analysed by univariate analysis, stratified analysis, multivariate analysis, and coefficient analysis. RESULTS: After treatment, the changes in the AOP-SN, POP-SN and AOP-POP angle were statistically different between the extraction and non-extraction groups. The results were consistent in different skeletal malocclusions and extent of crowding according to stratified analysis. After adjusting all confounding factors, the cant of the posterior occlusal plane was flattened further by 2.14 degrees in the extraction group than the non-extraction group after orthodontic treatment, and the AOP-SN and AOP-POP angle would further increase by 1.72 and 3.81 degrees, respectively. Although no significant differences were found between the two groups, the SNA, ANB, and Wits in the extraction group decreased more with increased counterclockwise rotation of the mandible. CONCLUSION: Compared to the non-extraction group, there were more increases in the AOP-SN and AOP-POP angle and more posterior flattening in patients with four premolar extractions despite different types of dentoskeletal malocclusion, which were correlated to the change of variables in sagittal and vertical dimensions such as Wits and FHI.

Maxillary sinus volume in patients with canted occlusal plane: A cone-beam computed tomography study.

OBJECTIVES: To compare the maxillary sinus volume between both sides in adult patients with upper occlusal canting (>2 mm cant) and a control group (≤2 mm cant) using cone-beam computed tomography scans. MATERIALS AND METHODS: This retrospective study included a total of 84 scans (42 scans per group) according to predetermined selection criteria. OnDemand 3-D™ software was used for volumetric and linear measurements of the maxillary sinus. Maxillary occlusal canting was determined at the level of the maxillary first molars. It was defined as the vertical difference between right and left sides relative to the Frankfort horizontal plane. Non-parametric tests were applied. RESULTS: The median difference in the maxillary sinus volume between the sides was statistically significant between the control and cant groups (P < 0.001). Also, the median difference in the maxillary sinus craniocaudal height and apex sinus distance between the sides was statistically significant between the control and cant groups (P < 0.05 and P < 0.001, respectively). CONCLUSION: In adult patients, maxillary occlusal canting of more than 2 mm was associated with asymmetric maxillary sinus volumes. In the cant group, maxillary first molars on the canted-down side were in close proximity to the sinus floor, which suggests a limited leeway for molar intrusion.

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.

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.

Analysis of the effect magnitude of different parameters on smile attractiveness.

OBJECTIVE: To evaluate the effect magnitude of different parameters on smile attractiveness. MATERIALS AND METHODS: A reference and 13 images were produced by manipulating 13 parameters. Image rating was performed with a 4-point Likert scale from least attractive (1) to most attractive (4). Image raters included laypeople, dental students, dentists, and dental specialists. Friedman and Wilcoxon image were used for estimate of effect size. Parameters were classified into small (0.10- < 0.30), medium (0.30- < 0.5), or large (≥0.50). RESULTS: A total of 1040 people participated with good consistency (α = 0.861), and moderate reliability (0.64-0.7). The reference image had the highest rank (laypeople:11.79, dental background: 12.55). For effect size; gingival margin level (-0.11, -0.01), teeth width proportion (-0.09, -0.10), inverted smile arch (-0.09, -0.21), commissure line cant (-0.15, -0.17) and low smile (-0.24, -0.23) had small effect size; occlusal plane cant (-0.36, -0.49), midline cant (-0.36, -0.48), and midline shift (-0.37, -0.49) had medium effect size; diastema (-0.55, -0.54) and color (-0.56, -0.56) had large effect size for the laypeople and dental groups. High smile (-0.42, -0.51), incisor edge symmetry (-0.46, -0.54) had medium effect size in laypeople group and large effect size in the dental group. Width to length tooth proportion (-0.26, -0.39) had small effect size in the laypeople group and medium effect size in the dental group. CONCLUSIONS: Smile parameters had different effect magnitude on smile attractiveness and were classified into small, medium, or large parameters. Neither laypeople nor professionals have a collective judgment on what constitutes a beautiful smile. CLINICAL SIGNIFICANCE: This study investigated the effect magnitudes of 13 smile parameters and presented a small, medium, and large smile parameters classification. It should provide the clinician with an insight into the expected effect each parameter has on the smile.

Vertical Control of a Severe Hyperdivergent Skeletal Class II Malocclusion with Steep Posterior Occlusal Plane in a Camouflage Case.

Severe hyperdivergent skeletal Class II malocclusion may be ideally treated with orthognathic surgery in adult patients. Here, we report a camouflage treatment of a 23-year-old female patient. She was diagnosed with a skeletal Class II malocclusion with extreme high mandibular plane angle, retrusive mandible, steep posterior occlusal plane, anterior open bite, and severe overjet. The treatment plan included extraction of all second premolars and intrusion of the maxillary anterior teeth and mandibular posterior teeth using miniscrews. These contributed to an effective counterclockwise rotation of the mandible, decreased lower face height, and improvement in anterior overbite. This case report shows a vertical control strategy on severe hyperdivergent skeletal Class II malocclusions, which achieves well-controlled sagittal and vertical dimensions and a favorable facial appearance. The treatment and retention results were well balanced and aesthetically pleasing.

Impact of counterclockwise rotation of the occlusal plane on the mandibular advancement, pharynx morphology, and polysomnography results in maxillomandibular advancement surgery for the treatment of obstructive sleep apnea patients.

PURPOSE: Evaluate the impact of counterclockwise rotation of the occlusal plane (CCWROP) on pharynx morphology and polysomnography in maxillomandibular advancement (MMA) surgery to treat obstructive sleep apnea (OSA) patients. METHODS: Prospective clinical trial of patients with OSA treated by MMA. Computed tomography and polysomnography were performed pre- and postoperatively and the parameters were compared. The surgery classified the patients into two groups: with (R) and without (NR) CCWROP. RESULTS: The study sample comprised 38 individuals: R (n = 19) and NR (n = 19). An anterior mandible advancement of 0.71 mm was identified for each degree of CCWROP (p < 0.001). As for polysomnography, the apnea-hypopnea index was reduced by 80% and 62% in R and NR, showing final values of 6.8 and 13.0, respectively. The apnea index changed equally in both groups. Reduction of 68 and 26% in the hypopnea index was observed for R and NR, respectively, with no statistically significant difference. Total volume increased by 45% in R and 30% in NR. Retropalatal and retrolingual volumes increased by 49% and 4% in R and 43% and 15% in NR, respectively. The minimum axial area increased by 92% in the retropalatal region and 97% in the retrolingual region in R, whereas these increases were of 76% and 31% in NR, respectively. CONCLUSION: Anterior mandibular advancement of 0.71 mm for each degree of CCWROP is of great importance for surgical planning. As a result of this resource, individuals in R presented better results than those in NR in all parameters assessed, especially regarding the retrolingual region.

Relationship of natural occlusal plane with different anatomical landmarks.

OBJECTIVE: To evaluate the parallelism of natural maxillary occlusal plane with inter-pupillary line and ala-tragus line, and to evaluate the anatomic relationship of natural mandibular occlusal plane with retromolar pad among dentate subjects. METHODS: The cross-sectional study was conducted from September 2017 to February 2018 at Fatima Jinnah Dental College, Karachi, and comprised front and profile photographs of subjects aged 20-28 years while holding the camper's plane against the maxillary occlusal plane. The photographs were imported in a software and an interpupillary line was drawn and the angle with Camper's plane was measured. On both profile pictures, lines were drawn from base of the ala to the superior, middle and inferior points on the tragus. The angle between ala-tragus line and Camper's plane were measured. Intra-orally, height of the mandibular occlusal plane in relation to the retromolar pad was evaluated using a stainless steel scale. Data was analysed using SPSS 23. RESULTS: Of the 109 subjects with a mean age of 23.03±1.36 years, 76(69.72%) were females. Horizontal parallelism of occlusal plane with inter-pupillary line was observed with a mean angle of 1.17±1.27 degrees. The angle between the occlusal plane and the inferior ala-tragus line was 4.25 degrees on the right side, and 4.50 degrees on the left. Intraorally, mandibular occlusal plane coincided with the inferior 48(44%) and the middle third 48(44%) of the retromolar pad. CONCLUSIONS: Inter-pupillary line and retromolar pad area should be used as a guide in the determination of plane of occlusion. The ala-tragus line was not found to be a reliable guide.

Management of Class II Hyperdivergent Mandible by Surgically Altering Occlusal Plane Pattern through Counterclockwise Rotation of Mandible.

AIM AND OBJECTIVE: To evaluate the facial esthetic of class II hyperdivergent mandible by altering the high mandibular plane angle into an orthognathic mandibular plane angle by counterclockwise (CCW) rotation of the mandible. MATERIALS AND METHODS: Five patients with class II hyperdivergent mandible were selected for this study. Initially, preorthodontics was done by aligning the teeth. Then, surgically, bilateral sagittal split osteotomy (BSSO) advancement with CCW rotation of mandible with a posterior open bite of 4 mm was done. Eleven linear and 11 angular measurements were taken. Pre- and postsurgical values were evaluated by composite cephalometric analysis, and the changes in the occlusal plane and facial height were statistically analyzed by using paired t-test. Jarabak ratio was calculated for facial height measurements. Further finishing will be done by postsurgical orthodontic procedures to get functional occlusion. RESULTS: Change in occlusion to class I is seen in values of Jarabak ratio and Go-Gn. Jarabak ratio shows an increase in posterior and decreases in anterior facial height. Go-Gn, which implies the CCW movement of the mandible, has reduced the anterior open bite and created a posterior open bite of 4 mm for the supraeruption of teeth. CONCLUSION: BSSO with CCW rotation of mandible with a posterior open bite has conservatively involved in single-jaw surgery, thereby improving the facial esthetics of all the patients taken this study. CLINICAL SIGNIFICANCE: This innovative method of CCW rotation of mandible with open bite mainly prevents the bi-jaw surgery, improves the stability, and gives an esthetically good appearance.

Clinical efficacy of counterclockwise rotating the functional occlusal plane using micro-implant anchorage.

To evaluate the therapeutic effect of using micro-implant anchorage (MIA) to rotate the functional occlusal plane (FOP) counterclockwise. Forty skeletal class Ⅱ high-angle patients who had completed orthodontic treatment were enrolled, including 20 patients treated with MIA orthodontic system (MIA group) and the other 20 patients treated with traditional sliding straight wire appliance (control group). Cephalometric measurements on the lateral cranial radiographs before and after treatment were performed, all acquired data were statistically analyzed with SPSS 26.0. At the end of treatment, MIA group obtained better effect of FOP and mandibular plane counter-clockwise rotation than the control group. In the MIA group, the average change of FOP-frankfort horizontal plane (FH), FOP-SN and mandibular plane angle (MP-FH) angle was -4.5(-7.3, -3.7)°, (3.3)° and -1.7(-3.0, -0.9)°, respectively. In the control group, the average change of FOP-FH, FOP-SN and MP-FH angle was -0.1(-4.1, 3.0)°, (-0.1±5.1)° and -0.4(-2.4, 0.7)°, respectively. There was significant difference between the change of the two groups (all <0.05). Compared with the traditional sliding straight wire appliance, counterclockwise rotation of FOP can be more effectively reversed by using MIA orthodontic system, and the MP-FH can be reduced as well.

Large versus small mandibular counterclockwise rotation during bimaxillary surgical correction of class II deformities-a retrospective CBCT study on skeletal stability.

OBJECTIVES: Postsurgical skeletal relapse is a concern for class II deformities corrected with counterclockwise rotation of the occlusal plane. Therefore, the aim of this study was to compare the skeletal stability between large and small counterclockwise rotational advancement of the mandible in patients with skeletal class II deformity. MATERIALS AND METHODS: This retrospective study included 50 adult patients with skeletal class II deformity corrected by Le Fort I setback and bilateral sagittal split osteotomy counterclockwise rotational advancement. Patients were divided into two groups, according to the amount of counterclockwise rotation: small rotation (n = 25) and large rotation (n = 25). Serial cone beam computed tomography scans were analyzed to identify skeletal and dental position from presurgery to at least 12 months postsurgery. Changes in the facial skeleton (maxilla and mandible) and teeth (central incisor and first molar) were determined for six skeletal and four dental landmarks by measures before treatment (T0) and 1 week postsurgery (T1), and from T1 to at least 12 months postsurgery (T2). RESULTS: A relapse was found both after large and small rotational advancement of the mandible (pogonion: 1.0 (2.4) mm and 1.4 (3.0) mm, respectively). The result was statistically significant (both p < 0.05) and was with less than 1.5 mm clinically acceptable. There were no between-group differences in the postsurgical horizontal and vertical mandibular stability. CONCLUSIONS: The results suggest that counterclockwise rotational advancement of the mandible using bilateral sagittal split osteotomy is a clinically stable procedure. The amount of rotation does not affect the postsurgical stability of the mandible. CLINICAL RELEVANCE: The findings help clinicians better understand the surgical and postsurgical changes of the skeleton and teeth after counterclockwise rotational advancement of the mandible for class II deformity.

A Comparative Radiographic Evaluation of Occlusal Plane in Dentulous and Edentulous Subjects: A Clinical Study.

AIM: The aim of this study is to establish a proportion between the inferior border of mandible and lower edge of the mental foramen and inferior border of mandible to occlusal plane for dentulous subjects and to evaluate the validity of this proportion in orienting the occlusal plane for edentulous subjects. MATERIALS AND METHODS: The occlusal plane was evaluated in the selected 50 dentulous and edentulous subjects for its relation to the mental foramen and inferior border of the mandible. The orthopantograms obtained were traced with the markings and the measurements were tabulated under different headings. After measuring the distances, the proportion between the distances was determined. The mean proportions of dentulous, edentulous, male, and female subjects were evaluated. Then the proportion of male subjects was compared with that of female subjects and dentulous subjects with that of edentulous subjects. Comparison of proportion between the different groups was done by using unpaired t test. The mean and standard deviation (SD) were determined for each group separately and were compared within each group. From the calculated "t" value, "p" the probability for error was found out. RESULTS: In dentulous subjects, the proportion ranged from 1:3.53 to 1:4.40. The mean was 1:3.90. In edentulous subjects, the proportion ranged from 1:3.50 to 1:4.15. The mean was 1:3.84. On comparison, the difference between both the groups was 0.06. The difference was statistically insignificant (p = 0.14). In the comparison of dentulous male and female subjects, the difference obtained was 0.02. The difference was statistically insignificant (p = 0.77). The comparison of edentulous male and female subjects and the difference obtained was 0.03. The difference was statistically insignificant (p = 0.51). CONCLUSION: The derived proportion of 1:4 between the inferior border of mandible and mental foramen and inferior border of mandible and occlusal plane in edentulous patients as measured on an orthopantogram may yield a plane of occlusion similar to that existing in the dentulous state. CLINICAL SIGNIFICANCE: The above-drawn proportion between the inferior border of the mandible to the lower edge of the mental foramen and between the inferior border of the mandible and the occlusal plane in edentulous patients may yield a plane of occlusion which is oriented similar to that existing in the dentulous state. The proportions derived radiographically in this study can serve as a basis for future studies to establish the occlusal plane for edentulous subjects.

Determining the occlusal plane using hamular notch incisive papilla plane evaluator: An in vivo study.

AIMS: Identification and establishment of the occlusal plane in patients with impaired occlusal plane, presents a major hurdle for the execution of natural esthetics, speech, and function. The aim of this study was to minimize such errors while occlusal rehabilitation, and employ hamular notchincisive papilla (H.I.P) plane as landmark and scribe it on the cast using H. I. P evaluator and utilise for occlusal corrections. SETTINGS AND DESIGN: HIP plane being parallel to the occlusal plane could ease the operator when it could be scribed on cast to analyze and restore the compromised occlusal plane. MATERIALS AND METHODS: Dentulous casts of two hundred participants were mounted on the Hanau Wide-Vue articulator. Reference points were marked on the maxillary right central incisor and maxillary molars on casts for attaining different occlusal planes, the incisive papilla and hamular notch region were also marked for HIP plane. A plane parallel HIP was scribed on cast using HIP Evaluator. The casts were then scanned using a three-dimensional coordinate measuring machine attached to perception V5 laser scanner and measurements were made using Geomagic X design software. The most parallel occlusal plane to HIP plane was evaluated, and the reliability of HIP evaluator was verified. STATISTICAL ANALYSIS USED: ANOVA test, Post hoc-Bonferroni test, and independent sample "t"-test were carried out for the comparison between occlusal planes, among the genders and for the analysis of the angle of deviation of scribed plane on the cast to HIP plane on the right and left sides. RESULTS: Occlusal plane III (Mesio-labial incisal edge of upper right central incisor to Mesio-buccal cusp tips of upper second molars) showed least angle of deviation with 1.316° ± 1.158° to HIP plane among tested subjects. There is no significant difference between the genders. The plane scribed on the cast with H. I. P evaluator showed relative parallelism to H. I. P plane with minimum deviation of 0.010° ± 0.363°. CONCLUSION: Occlusal plane III is more parallel to H. I. P plane. Scribed plane on the cast using H. I. P evaluator is parallel to H. I. P plane. H. I. P evaluator can be used as an alternative tool to establish the occlusal plane to rehabilitate patient with deficient dentition or disordered occlusal plane.

Layperson's preference of the transverse occlusal plane in asymmetric facial model.

OBJECTIVE: Facial asymmetries are common, especially deviated nose and chin. The clinician must consider these variables when establishing the smile, placement and angulation of the occlusal plane. The purpose of this article is to determine if nose and chin deviations affect the perception of laypeople towards different angulations of the occlusal plane cant. MATERIALS AND METHOD: An asymmetric facial model was created from a symmetric facial model used in a previous study. Nose and chin were deviated 3 mm to the left and eight different pictures were created, each with different degrees of occlusal plane cant in both direction. Using a visual Likert scale delivered via Websurvey within the private practice setting, 120 randomly selected laypersons evaluated each image according to their own beauty preferences. RESULTS: In an asymmetric face, nose and chin deviated 3 mm to the left, a minor occlusal plane angulation of 2° can be perceptible regardless of the direction of the cant. CONCLUSIONS: The occlusal plane should be as parallel to the interpupillary line as possible. If occlusal cant is present, less than 2° of angulation it is preferable, regardless of the direction of the nose and chin. CLINICAL SIGNIFICANCE: In the presence of an asymmetric face, the occlusal plane should be as parallel as possible to the interpupillary line. The direction of the deviation of the nose and the chin are irrelevant factors to determine the occlusal plane. An inclination of the occlusal plane can cause vertical discrepancy, which could subsequently create malocclusion. A complete dentofacial analysis can aim at assessing the angulation of the occlusal plane not only for esthetic outcomes, but for also allowing correct occlusal function.

A device for occlusal plane determination.

The correct orientation of the occlusal plane is the first and one of the important steps while recording jaw relationships in an edentulous patient. One of the most popular methods is to orient the occlusal plane to interpupillary line anteriorly and ala-tragus lines posteriorly which is usually accomplished by repetitive adjustment of the maxillary rim until a hand-held Fox's plane appears to be parallel to these lines. However, this process is time-consuming and error-prone. The eventual plane is almost always an educated guess, and this can be difficult for a new student. The device presented in this article marks the occlusal plane on wax rims parallel to interpupillary line anteriorly and the ala-tragus lines posteriorly, and thus, occlusal plane can be oriented in one simple step, thereby saving time and increasing efficiency of the operator.

Skeletal Stability After Mandibular Counterclockwise Rotational Advancement for Correction of Skeletal Class II Deformity-A Systematic Review and Meta-analysis.

OBJECTIVES: The aim of this systemic review was to compare surgical and postsurgical changes in the mandible after bilateral sagittal split osteotomy (BSSO) with counterclockwise (CCW) rotational advancement. A review of the current available dental literature regarding skeletal stability after mandibular CCW rotational advancement for skeletal Class II deformity was performed using a qualitative and quantitative analysis (meta-analysis). MATERIAL AND METHODS: Five databases were searched: PubMed, MEDLINE (Ovid), Science Direct, Scopus, and Web of Science. The systematic review and meta-analysis addressed the stability of BSSO CCW rotational advancement and the effect of the amount of CCW rotation on skeletal stability after BSSO advancement. Meta-analysis was performed only for studies reporting point B position in mm or mandibular plane angle in degrees before and after surgery and at follow-up. RESULTS: The database search resulted in 284 articles after removal of duplicates, and an additional 3 articles were included from hand searches of the bibliographies of the selected articles and relevant reviews. Eight studies were included in the systematic review; all were retrospective case series, and all used rigid fixation. Only 1 study was of medium quality; all other studies were of low quality. Meta-analysis of 3 studies revealed a mean forward movement of 7.6 mm at point B (95% confidence interval [CI], 4.07 to 11.4), a mean downward movement of 2.6 mm (95% CI, -0.66 to 5.84), and a mean CCW rotation of mandibular plane of 4.3° (95% CI, -6.34 to -2.19) during surgery. After surgery, point B showed a mean backward movement of -0.18 mm (95% CI, -1.30 to 1.14), a mean upward movement of -0.5 mm (95% CI, -3.00 to 1.98), and a mean clockwise rotation of 0.1° (95% CI, -1.76 to 1.91). CONCLUSIONS: Meta-analysis showed mandibular CCW rotational advancement is a stable procedure, both horizontally and vertically. However, the conclusions are far from robust due to the small sample size and poor quality of the reviewed studies.

Morphometric analysis for evaluating the relation between incisal guidance angle, occlusal plane angle, and functional temporomandibular joint shape variation.

OBJECTIVE: The correlations between morphology of the temporomandibular joint structure, the anterior guidance angle, and occlusal plane were investigated. MATERIALS AND METHODS: A cone beam computed tomography analysis was performed in 158 patients (86 women and 72 men). 3D software was employed to obtain the coordinates of the shape of the incisal guidance angle, occlusal guidance angle, articular fossa, and mandibular condyle. Generalized Procrustes analysis including principal components analysis (PCA) were performed and produced principal components (PCs) scores of each shape and their centroid size (CS). RESULTS: A significant Pearson correlation coefficient of 0.3451 (p < .001) was observed between the incisal guidance angle and occlusal plane. The CS also showed a correlation with the incisal guidance angle, but not with the occlusal plane angle. The PCA results revealed that there were no significant correlations between the temporomandibular joint structure (TMJ) shape (fossa and condyle) and the incisal guidance angle. CONCLUSIONS: Incisor guidance angle and occlusal plane angle were correlated. In addition, there was a correlation between CS and incisal guidance angle. In the PCA, It can be concluded that the size is more related to the incisor guidance angle than the morphological factors of the constituent components of the TMJ.