Anterior Overbite Research Articles

Study on the occlusal stability after three years of full-mouth occlusal reconstruction in maximum intercuspal position

Objective: To observe the stability of vertical dimension of occlusion (VDO) and mandibular position in full-mouth occlusal reconstruction subjects by means of digital occlusal analysis. Methods: Six subjects who had completed full-mouth occlusal reconstruction by intraoral functional generated path technique for more than three years in the Department of Prosthodontics, Peking University School and Hospital of Stomatology were enrolled for follow-up observation, all six patients were male, with an age of (53.6±8.4) years. The digital dentition model and occlusal contact at baseline and three years follow-up review after restoration were recorded by intraoral laser scanning, and the changes in occlusal surface morphology, occlusal contact area and mandibular position (mandibular overall deviation and mandibular reference plane average angle deviation) were measured in reverse engineering software. The Wilcoxon signed rank test was used to statistically analyze the changes of horizontal and vertical overbite of anterior teeth and VDO of posterior teeth between baseline and three years follow-up after reconstruction. Results: The prosthesis in the 6 subjects were intact at the time of follow-up, and there was no significant change in occlusal morphology compared with that at the baseline right after restoration delivery, and the occlusal contact in maximum intercuspid position was stable. The overall deviation of the lower jaw was (0.19±0.06) mm, and the angular deviation of the mandibular reference plane was 0.72°±0.38°. The chromatic scale of occlusal contact showed that the occlusal contact in some areas was heavier during the three years post-delivery, and the overbite of anterior teeth and the VDO of posterior teeth showed no statistical difference compared with that in the baseline (P>0.05). Conclusions: This study suggests that the occlusal contact distribution and jaw position relationship can be maintained after 3 years of full-mouth occlusal reconstruction, and there is no significant change in the anterior overbite and VDO.

Full Mouth Rehabilitation for a Patient with Angle's Class II Division 2 Associated Deep Overbite and Worn Dentition - Case Report With 2-Year Follow-Up and Literature Review.

Some of the critical clinical challenges encountered in the treatment of adult patients with deep overbite and worn dentition include correction of deep overbite, establishment of an appropriate occlusal vertical dimension (OVD), and maintenance of long-term occlusal stability. Although Angle's Class II division 2-associated deep anterior overbite is common in orthodontic treatment, simple prosthodontic treatment with great improvement of deep anterior overbite and worn dentition is infrequently reported. A 51-year-old man with Class II Division 2 malocclusion presented with hypo-divergent facial pattern, reduced lower facial height, and protuberant lips. Intraoral examination revealed unevenly worn dentition and an Angle's Class II division 2-associated deep and traumatic anterior overbite. Based on the challenges of the presentation, it was imperative to design an protocol to ensure a predictable and favorable prognosis. According to the current protocols, prosthetic treatment of occlusal rehabilitation was applied. Following the 3-month evaluation period using interim prostheses, full-mouth ceramic restorations were completed. Significant post-treatment functional and aesthetic improvements were achieved with resultant stable inter-incisal contacts either immediately after treatment or during the 2-year follow-up period. Full mouth rehabilitation offers brilliant prospects for improved function, enhanced aesthetics, and improved health of the entire stomatognathic system of Angle's Class II division 2 patient associated with deep overbite and worn dentitions.

Factors affecting unusual postoperative vertical downward movement of mandible after surgery-first approach using intraoral vertical ramus osteotomy

BackgroundIn very rare cases, patients who have undergone surgery-first approach with intraoral vertical ramus osteotomy (IVRO) exhibit unusual downward movements of mandible even up to 1-year post surgery, which makes it difficult for orthodontists to stabilize the occlusion during the postoperative orthodontic period. The aim of this study was to identify factors affecting the unusual downward movement of the mandible 1-year after the surgery-first approach using IVRO, while focusing on cephalometric values.MethodsThis retrospective cohort study sample was divided into two groups based on the amount of vertical movement of the B-point 1-year post surgery (Group S, predictable upward movement; Group U, unpredictable downward movement greater than 2 mm). To evaluate cephalometric changes between the two groups, cephalograms were obtained before surgery, 1 day after surgery, 1 month after surgery, and 1 year after surgery. The data were analyzed using the independent t-test, Mann–Whitney U test with Bonferroni correction, Pearson correlation analysis, and multiple regression analysis.ResultsAt the initial examination, Group U showed a shallower anterior overbite. The vertical surgical change in the B-point was statistically different between the two groups (p < 0.001), indicating that group U exhibited more upward movement of the mandible during surgery. Group U showed significant downward movement of the mandible 1 month after surgery, and this finding persisted until 1 year postoperatively. Clockwise rotation of the mandible was also observed. Surgical vertical movement of the B-point showed a strong correlation with postoperative vertical movement of mandible (r = -0.674; p < 0.001) along a linear relationship, indicating that the amount of postoperative vertical downward movement of the mandible increased as the amount of surgical upward movement of the B-point increased (R2 = 0.449; p < 0.001).ConclusionsThis study revealed that unusual downward movement of the mandible after a surgery-first approach using IVRO is correlated with the amount of upward movement during the surgery. When planning surgery, in cases in which a significant upward movement of the mandible is anticipated, orthodontists should prepare for the possibility of subsequent unusual downward movement and a tendency for the anterior overjet to decrease during the postoperative orthodontic period.

Loss of attachments in patients during orthodontic therapy with clear aligners: A prospective clinical study.

This study aimed to assess the loss rate of attachments and investigate its probable influencing factors in patients during orthodontic therapy with clear aligners. A total of 55 patients treated with clear aligners were enrolled in this prospective clinical study. The loss rate of attachments was evaluated after a 6-month follow-up since the initial bonding was finished. The attachment survival curves were gone through Kaplan-Meier estimates. The Cox regression model with shared frailty was conducted to evaluate the hazard ratios (HRs) for the following factors, including sex, age, dental malocclusion, vertical skeletal pattern, anterior overbite, operators, tooth extraction, attachment amount, arch, tooth position and attachment type. There were a total of 47 patients (14 males and 33 females; and mean age: 26.77 ± 8.45) in which 722 attachments were involved in the final analysis. During the 6-month follow-up, 99 attachments were lost by 40 participants. The overall loss rate was 13.7%. The loss of attachments was more common in the early months of therapy. During the first 2 months, 71 attachments were lost. The loss rate of attachments was not significantly affected by sex, age, dental malocclusion, vertical skeletal pattern, anterior overbite, operators, tooth extraction, attachment amount and attachment type (P > 0.05). The loss rate of mandibular attachments was 1.8 times that of maxillary attachments (HR = 1.8; 95% CI: 1.2-2.8; P = 0.009). The loss rate of molar attachments was 5.5 times that of incisor attachments (HR = 5.5; 95% CI: 1.6-19; P = 0.007). During the first 6 months, the overall loss rate of attachments was 13.7%. In the early months of therapy, loss of attachments was more common. The loss rate decreased as treatment time increased. Loss of attachments was significantly affected by arch and tooth position, with higher loss rates in the mandibular arch and molars. Besides, loss of attachments was not affected by sex, age, dental malocclusion, vertical skeletal pattern, anterior overbite, operators, tooth extraction, attachment amount and attachment type.

Effect of occlusal hypofunction on centre of resistance in maxillary central incisor using the finite element method.

To determine differences in the location of centre of resistance (Cres) between functional and hypofunctional teeth and to evaluate the relationship between the pulp cavity volume and locations of the Cres, using the finite element (FE) method. Retrospective cohort study. FE models of right maxillary central incisor, derived from cone-beam computed tomography (CBCT) images of 46 participants, were divided into normal function (n = 23) and hypofunction (n = 23) groups using anterior overbite and cephalometric measurements. Measurements of the tooth and pulp cavity volume were made from the CBCT. Cres levels were presented as percentages of the root length from the root's apex. All data were analysed and compared using the independent t-test (P < 0.05). The relationship between the location of Cres and volume ratios were evaluated statistically. The means of the pulp cavity/tooth volume and root canal/ root volume ratio of the maxillary central incisor in the anterior open bite group were significantly greater than those in the normal group. The average location of Cres in the anterior open bite group was 0.6 mm (3.7%) apically from the normal group, measured from root apex. The difference was statistically significant (P < 0.01). There was a significant correlation between root canal/root volume ratio and locations of Cres (r = -0.780, P < 0.001). The Cres in the hypofunctional group was located more apical than the functional group. As the pulp cavity volume increased, the level of Cres shifted apically.

Class II and anterior open bite malocclusion treated with mini-implants, intermaxillary elastics, speech therapy, and retained with a night-wear palatal crib wraparound

The teeth position in anterior open bite malocclusion depends on a balance of pressure between the tongue and lips and the treatment planning should include such variables. The objective of this study was to report an orthodontic case of an adult with maxillary protrusion and anterior open bite treated with skeletal anchorage and intermaxillary elastics. The patient presented a Class II malocclusion with anterior open bite, without a history of non-nutritive habits, and mandibular missing teeth at 54 years old. Mini-implants were inserted in the maxillary molars region to produce distal movement of the maxillary dentition while controlling molar extrusion, and in the mandibular anterior region on the left side to produce mesial movement of posterior teeth. Up and down intermaxillary elastics were worn in the area of the incisors to treat the open bite together with Class II intermaxillary elastics. Cleats were bonded in the lingual surface of the anterior teeth as spurs to the tongue posture. However, the best result on the anterior open bite treatment was coincident with the speech therapy. Normal relationships between the maxillary and mandibular occlusal plane of cusps, correct anterior overbite, and adequate proximal relationships were obtained at the end of treatment. The retention modality to the maxillary arch was daily wear of a removable standard wraparound and a night-time wraparound with the palatal crib. The new technology allows for more effective treatment in adults and speech therapy was helpful to achieve balanced pressure between the tongue and lips.

Three-dimensional evaluation of the pharyngeal airway space in patients with anterior open bite.

: This study aimed to three-dimensionally evaluate the pharyngeal airway space (PAS) of patients with anterior open bite (AOB) by using cone-beam computed tomography (CBCT) and compare the findings with those obtained in individuals with normal occlusion. : The open bite group (OBG, n = 25) consisted of patients with an anterior overbite of -3 mm or less, while the control group (n = 25) consisted of age- and sex-matched individuals with an anterior overbite of 1-3 mm, Angle Class I malocclusion (1° ≤ point A-nasion-point B angle ≤ 4°), and a normodivergent profile (22° ≤ Frankfort mandibular plane angle ≤ 28°). After the CBCT data were reconstructed into a three-dimensional image, the PAS was segmented into four parts, and the volume of each part was measured. Pharyngeal airway length (PAL) and the area and transverse width of the part showing minimal constriction were also measured. Pearson's correlation analysis was used to evaluate the correlation between changes in the PAS and the amount of anterior overbite. : The OBG showed a significantly narrower airway space in the nasopharyngeal, hypopharyngeal, and total airway volumes. The OBG also showed a significantly smaller area and transverse width of the part with minimal constriction. The OBG showed a significantly longer PAL, but there was no correlation between the amount of anterior overbite and the changes in PAS. : The PAS was associated with AOB. Patients with AOB had a narrower PAS and a smaller part showing minimal constriction.

Three-Dimensional Analysis of Alveolar Bone Morphological Characteristics in Skeletal Class II Open Bite Malocclusion: A Cone-Beam Computed Tomography Study.

This cross-sectional research evaluated the morphological characteristics of alveolar bone in skeletal class II open-bite individuals compared to skeletal class II and class I non-open-bite individuals. A sample of 82 patients (all were in cervical vertebral stage 6) was divided into three groups (class II OB group, n = 29; class II NOB group, n = 29; class I NOB group, n = 24) according to bilateral molar relationship, ANB angle, and anterior overbite measured by cephalometric analysis. The evaluation was performed with specialized software (Mimics 21.0) and initial cone-beam computed tomography (CBCT) data. The alveolar bone height and thickness of the whole dentition area and alveolar crest level and root apex position of the incisors were measured with a series of appropriate CBCT images. One-way analysis of variance followed by the Tukey post hoc test and the Kruskall−Wallis test were performed for statistical comparisons. The class II open-bite group had increased alveolar bone height for the maxillary first molar and decreased alveolar bone height for mandibular molars compared to the class II non-open-bite group (p < 0.05 for both). Furthermore, there were significant negative correlations between the alveolar bone heights of the upper first and second molars (A6-height, A7-height) and overbite (both p < 0.01). The alveolar thicknesses of all measured teeth were generally reduced in the class II OB group.

A COMPARATIVE ELECTROMYOGRAPHIC STUDY OF TEMPORALAND MASSETER MUSCLE IN CLASS I AND CLASS II DIVISION I CASES

Aim- The purpose of this study was to record the electromyographic activity of the temporalis and masseter muscles in normal and Angle's class II division 1 cases in maximal biting in intercuspal position and during chewing and to compare the activities of the two muscles in class II division 1 cases with those of normal occlusion. Materials And Methods- 15 subjects of Angle's class II division 1 malocclusion with deep anterior overbite, skeletal class II pattern with ANB angle greater than 4° and normal mandibular plane angle were selected. The 15 normal occlusion subjects had normal overjet and overbite with class I dental arch and normal mandibular plane angle. All the subjects were male of 9-15 years of age, with full compliment of teeth particular for that age, were free of any temporomandibular joint disorder and had no history of previous orthodontic treatment. Electromyographic activity of the temporal and masseter muscles of both sides were recorded during maximal biting in intercuspal position and during chewing of peanuts. The peak to peak amplitude was obtained from the raw EMG data using the integrated software. The average peak to peak amplitude in uv were used for statistical analyses. Results And Conclusion-The results revealed that there was no statistically signicant differences in activity of the muscles of the right and left sides in both the groups. The activity of the masseter muscle in both maximal biting and chewing was signicantly higher in class I group. In class II division 1 group although the masseteric activity was higher, it was not statistically signicant. Comparison between the groups showed that the masseteric activity was signicantly higher in class 1 group for both chewing and maximal biting. The temporalis activity was also signicantly higher for class I group during chewing, but the difference in temporalis activity during maximal biting, although higher in class I group, was not statistically signicant.

Influence of the Text Neck Posture on the Static Dental Occlusion.

Background and Objectives: The excessive use of smartphones for various tasks led to a new adverse postural phenomenon called text neck. The aim of this study was to investigate the effect of the text neck posture (TNP) on static occlusion by using the T-Scan III occlusal diagnostic system. Materials and Methods: Nineteen subjects (aged 20 to 24 years) were considered for this research. They had normal values for anterior overbite and overjet, Angle Class I occlusion, no posterior crossbite, and no signs or symptoms of cervical or temporo-mandibular disorders. Occlusal registrations were performed with the T-Scan III system in a normal, neutral head posture (NHP), as well as in the TNP. The investigated parameters were: occlusion time (OT), asymmetry index of the occlusal force (AOF), percent of the maximum movie force (%MMF), and the time elapsed from the last occlusal contact until the maximum intercuspation (MAT-OTB). The last three parameters were analyzed in the maximum area frame (MA) of the registrations. For the statistical analysis of the recorded data, the Wilcoxon Signed Ranks test and the Spearman’s correlation coefficient were used. Results: The following values were obtained in NHP and in TNP: for AOF, 14.88 ± 10.39% and 18.04 ± 12.83%, respectively; for OT, 1.34 ± 1.84 s and 1.32 ± 1.8 s, respectively; for the %MMF, 97.5 ± 2.83% and 96.31 ± 3.17%, respectively; for MAT-OTB, 2.08 ± 1.82 s and 1.45 ± 2.3 s, respectively. There were no statistically significant differences between the static occlusal parameters measured in NHP and those in TNP. However, the high values of the AOF and OT in NHP revealed an imbalance of the occlusal force distribution between the right and left side in maximum intercuspation (MI), as well as a lack of simultaneity of static occlusal contacts. Furthermore, there was a significant, direct, and strong correlation between OT and AOF in NHP. Conclusions: The NHP should not be used as the starting position in TNP simulations in T-Scan studies, so as to avoid statistically insignificant differences between static occlusion in NHP and TNP. The healthy standing subjects, with normal occlusal relationships from the clinical point of view, revealed an occlusal instability in NHP when examined with the T-Scan.

Are morphological and morphometric characteristics of maxillary anterior region and nasopalatine canal related to each other?

The main purpose of this article was to clarify the relationship of anterior bone and tooth morphology with NPC. The anatomical features of the NPC region in three dimensions from coronal, axial, and sagittal directions were analyzed using CBCT and the effects of age, gender, sagittal root positions (SRPs) of central teeth, anterior overbite depth (AOD), central incisor (CI)/palatal plane (PP) angle, NPC/PP angle, and collum angles (CA) on NPC were evaluated in a group of the Turkish population. In this retrospective study, CBCTs of a total of 330 individuals between the ages of 17 and 82 were evaluated. The effects of SRP, AOD, CI/PP angle, NPC/PP angle and CA on the anatomical features of NPC were examined on the basis of age and gender. Descriptive statistics, Kolmogorov-Smirnov, Chi-square, Wilcoxon, Mann-Whitney-U, Kruskal-Wallis, and Spearman correlation tests were used. p values of < 0.05 were accepted as statistically significant. While the SRPs, CI/PP angle, NPC/PP angle, CA, and age did not differ statistically according to NPC shape (p > 0.05), NPC shape varied according to gender and AOD (p < 0.05). It was found that cylindrical NPC (32.8%) was more common in females, while conical-shaped NPC (30.7%) was more common in males (p < 0.01). While most conical NPC was detected in individuals with Class I overbite depth, cylindrical NPCs were found in Class II and III individuals (p < 0.01). The results showed that gender and AOD are influential factors on NPC shape. While conical-shaped NPC is more common in individuals with bite depth incisal, cylindrical-shaped NPC is more likely to be seen in individuals with middle and cervical thirds.

Efficacy of Bite Opening in Begg's Technique

Introduction: With the introduction of Begg’s, technique there isopening up of deep anterior overbite by depressing both upper and lower anterior teeth in their sockets. The aim of the study was to evaluate the efficacy of bite Opening by the Begg technique during the first stage of treatment cephalometrically. Materials and Methods: Materials for the study consisted of thirty pre-treatment and end of stage 1 cephalograms taken of patients treated with Begg mechanics. Tracing of the radiographs of Class I, Class II division 1 and Class II subdivision malocclusion cases were made and reference planes were drawn. The difference between the pre-treatment and stage-I measurements for all the sixteen parameters were analysed statistically. The student paired t-test was applied to determine the level of significance. Results: The estimation of apparent bite opening due to lower incisor proclination was derived using correlation coefficient and the regression equation was estimated. Overbite is reduced markedly with a mean of 4.66 +/- 1.637 mm, which is statistically highly significant. The result showed an apparent bite opening with a mean value of 1.97+2.44 mm which is statistically highly significant. Conclusion: Overbite was reduced markedly in all the cases with this technique used by Begg’s and mandibular incisors showed a marked amount of intrusion, which accounts for 63.6% of bite opening which is found to be the primary factor contributing to correction of deep overbites.

Effect of Orthodontic Treatment on Anterior Tooth Displacement in Patients with Periodontal Disease: A Meta-Analysis.

Objective To systematically evaluate the effect of orthodontic treatment (ODT) on anterior tooth displacement (ATD) in patients with periodontal disease. Methods PubMed, Web of Science, Embase, China National Knowledge Infrastructure, and Wanfang databases were electronically searched for relevant literature studies on ODT and basic treatment for ATD in patients with periodontal disease, and then the related journals and reference lists of the included studies were manually searched. The search time was set from January 2010 to May 2021. Stata 16.0 software was used for meta-analysis. Results Totally, 783 articles were retrieved, and finally, 14 studies were included. The effective rate of basic treatment combined with OTD was significantly higher than that of basic treatment alone (OR = 7.27, 95% CI: 3.76, 14.04). Specifically, the combined treatment led to lower values of periodontal pocket depth (SMD = −2.30, 95% CI: −2.94, −1.66), anterior overjet (SMD = −2.75, 95% CI: −3.72, −1.78), anterior overbite (SMD = −2.13, 95% CI: −3.16, −1.10), and periodontal bleeding index (SMD = −4.25, 95% CI: −5.48, −3.03) compared with those of basic treatment alone. Conclusion Compared with basic treatment, ODT combined with basic treatment is more effective for patients with periodontal disease-caused ATD and can also improve the clinical symptoms of patients.

The Relation among Teeth and Maxillary Dental Arch Dimensions with Anterior Teeth Angulation and Inclination.

Objectives This study aimed at finding out whether anterior teeth angulation and inclination have a relationship with the maxillary teeth and dental arch dimensions. Methods Fifty study models with normal occlusion were selected from the archive of the Department of Orthodontics at Baghdad Dental Faculty. Maxillary dental arch width and length at different points were determined in addition to measuring anterior teeth angulation, inclination, crown thickness, overjet, overbite, and Bolton's ratios. The unpaired t-test and Pearson's correlation coefficient test were used for data analysis. Results No statistical gender differences were reported in all measurements except the dental arch widths and length where males had significantly higher mean values. Only the maxillary incisor's inclination showed a direct weak significant correlation with the total arch length. Conclusions The inclination of upper incisors had a minimal effect on increasing dental arch length.

Cephalometric evaluation of changes in vertical dimension and molar position in adult non-extraction treatment with clear aligners and traditional fixed appliances.

ABSTRACTIntroduction: Orthodontists have been using clear aligners to treat malocclusions, and one potential effect of treatment with orthodontic aligners is the intrusion and/or resists extrusion of the posterior teeth. This “bite-block effect” is primarily anecdotal due to the frequent occurrence of posterior open bites in patients after clear aligner therapy. Objective: The purpose of this study was to compare changes promoted by clear aligners and traditional fixed appliances in cephalometric measurements of the vertical dimension and molar position in adult patients with Class I malocclusion treated with non-extraction. Methods: Pre- and post-treatment lateral cephalometric radiographs of adult patients treated with either clear aligners (n=44) or traditional fixed appliances (n=22) were selected for retrospective analysis. Eight interval measurements and one nominal measurement were evaluated: anterior overbite (OB), mandibular plane angle related to cranial base (SN_MP) and related to Frankfort (FMA), lower molar height (L6H) and upper molar height (U6H), palatal plane to mandibular plane angle (PP_MP), lower facial height (LFH), total facial height (TFH), and posterior open bite (Posterior_OB). A single evaluator traced all cephalographs, and changes in select measures of the vertical dimension were compared within and between groups. Results: OB decreased (1.15 mm) and L6H increased (0.63 mm) in the traditional fixed appliance group. Mandibular plane angles (related to cranial base and to Frankfort) increased (0.43° and 0.53°, respectively) in the clear aligner group, but just FMA showed significant difference between groups (difference of 0.53°). LFH and TFH increased (ranging from 0.52 mm to 0.80 mm) in both groups, with no differences between treatment modality. Presence of visible posterior open bite significantly increased over the course of treatment. OB, FMA and L6H exhibited an interaction between treatment stage (pre- and post-treatment) and modality (clear aligner therapy and traditional fixed appliances), but no interaction among these three variables was found. Conclusions: The evidence does not support the theory that clear aligner therapy produces better vertical dimension control than traditional fixed appliances. Traditional fixed appliance therapy slightly extruded the lower molar, and clear aligner therapy produced a slightly mandibular backward rotation.

Prosthetic treatment for patient with anterior overbite and partial edentulism using maxillary hybrid telescopic double crown RPD and mandibular fixed prostheses: A 11-yr follow-up

Prosthetic treatment for patient with anterior overbite and partial edentulism using maxillary hybrid telescopic double crown RPD and mandibular fixed prostheses: A 11-yr follow-up

Evaluation of the facial soft tissue changes in skeletal anterior open bite patients treated with rapid molar intruder appliance using cone beam computed tomography

Aim: The aim of this study was to evaluate the facial soft tissue changes in skeletal anterior open bite patients treated with rapid molar intruder appliance using cone beam computed tomography (CBCT). Materials and Methods: This retrospective study included 2 groups. The first treatment group included randomly selected CBCT scans of 20 skeletal open bite patients (8 males and 12 females, mean age 11.6±1.1 years) who were treated with the rapid molar intruder appliance (RMI) for molar intrusion. The CBCT scans were taken before treatment (T1) and after open bite correction (T2). The facial soft tissue changes in the treatment group were compared with a closely matched second untreated control group with normal anterior overbite (9 males and 11 females, mean age 11.9± 1.2 years). Results: The first group showed significantly greater decreases in the angle of facial convexity and the H angle than the second group. The first group showed significantly greater increases in the lower lip protrusion and the soft tissue chin prominence than the second group. The upper lip protrusion and the soft tissue facial height were decreased in the first group and increased in the second one. The difference was statistically significant. The nasolabial angle was increased in the first group and decreased in the second one. The difference was statistically significant. Conclusions: Molar intrusion using the rapid molar intruder appliance (RMI) could result in significant improvement in the facial soft tissue profile in skeletal anterior open bite patients.

Primary Retention of Molars and RANKL Signaling Alteration during Craniofacial Growth.

The primary retention of molars observed in clinic corresponds to a still-unexplained absence of molar eruption despite the presence of an eruption pathway, resembling the experimental transient inhibition of RANKL signaling in mice. The aim of the present study was to confront the hypothesis according to which the primary retention of molars is associated with transitory perturbations to RANKL signaling during growth as part of a wider craniofacial skeleton pattern. The experimental strategy was based on combining a clinical study and an animal study corresponding to the characterization of the craniofacial phenotypes of patients with primary retention of molars and analyses in mice of the consequences of transient inhibition of RANKL signaling on molar eruption and craniofacial growth. The clinical study validated the existence of a particular craniofacial phenotype in patients with primary retention of molars: a retromandibular skeletal class II typology with reduced mandibular dimensions which manifests itself at the dental level by a class II/2 with palatoversion of the upper incisors and anterior overbite. The animal study demonstrated that transient invalidation of RANKL signaling had an impact on the molar eruption process, the severity of which was dependent on the period of inhibition and was associated with a reduction in two craniofacial morphometric parameters: total skull length and craniofacial vault length. In conclusion, primary retention of molars may be proposed as part of the craniofacial skeleton phenotype associated with a transitory alteration in RANKL signaling during growth.

Without mini-plates, mini-implants and surgery: treatment of severe anterior open bite in an adult patient - a case report

Introduction: Currently, there is a tendency to treat open bite with mini-implants, miniplates, and orthognathic surgeries and build ups when these protocols are not always indicated and to be apply them unnecessarily and excessively. Objectives: This case report describes treatment of a severe anterior open bite in an adult patient with step bends and vertical elastics. Case report: The female patient was 29 years and 8 months old and reported that she had low self-esteem; therefore, she wanted to have her untreated open bite closed. By examination, a convex profile, vertical growth pattern, dental midline deviation, and tongue exposure could be seen upon smiling. The dental and skeletal sagittal relationship was Class II. The overjet was +5 mm and the anterior overbite was -5.5 mm. The severe skeletal open bite involved the first molars to the anterior teeth, and it was treated only with step bends and vertical elastics over 2 years. Results: Significant facial improvement, maxillary incisor exposure upon aesthetic smiling, and adequate overbite and overjet were observed. The upper and lower dental midlines fit to the sagittal line. A counterclockwise rotation of the mandible was observed. The severe skeletal open bite was treated. Conclusions: Severe skeletal open bite malocclusion treated with step bends and vertical elastics in adult patient demonstrated efficient, predictable and stable open bite correction.

Anatomical relationship between the maxillary posterior teeth and the sinus floor according to an anterior overbite.

To evaluate the vertical relationship between the maxillary sinus floor (MSF) and the maxillary posterior teeth (MPT) according to an anterior overbite. The patients were divided into three groups according to an anterior overbite. The open bite group (OBG) included patients with an anterior overbite of ≤0mm, the normal overbite group (NBG) included patients with an overbite of 0-3mm, and the deep bite group (DBG) included patients with an overbite ≥3mm. Thirty patients were randomly matched into each group based on age and sex. The distances and vertical relationship between the MSF and the MPT was analysed using cone-beam computer tomography. The vertical relationship between the two was classified as either favourable or unfavourable for the intrusion of the posterior teeth. A higher ratio of patients in the OBG had MPT positioned close to the MSF than the DBG. Intrusion of the posterior teeth was unfavourable for an average of 87.2%, 77.2% and 70.2% molars in the OBG, NBG and DBG, respectively. The vertical distance between the MSF and the MPT is associated with an anterior overbite. The posterior teeth were in an unfavourable position for the orthodontic intrusion in the OBG as compared to the other groups. Additional caution is needed when planning orthodontic intrusion treatment for patients with an anterior open bite. But, there were some individual variations within each group.