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Successful correction of overbite and overjet after orthodontic treatment may be judged in terms of incisor overbite and inter-incisal angle. Removable appliances can produce worthwhile overbite reductions, but the final inter-incisal angle depends upon skeletal pattern. It is vital, therefore, to make an assessment of this factor when planning treatment for a Class II malocclusion.
Lateral cephalometric radiographs were evaluated to determine the posttreatment stability of 66 patients treated with LeFort I osteotomies to reposition their maxillae superiorly. The sample was divided into three groups based on the degree of pretreatment overbite: openbite subsample--no incisal overlap; overlap subsample--incisal overlap and no incisal contact; contact subsample--incisal overlap with incisal contact. The cephalograms were superimposed and linear measurements were made at each interval (pretreatment, posttreatment, and at least one year posttreatment). The results clearly show that the three subsamples reacted differently during the posttreatment interval. 42.9 percent of the subsample with pretreatment openbite showed a significant increase in facial height, significant eruption of maxillary molars, and a significant decrease in overbite. 28.6 percent of the openbite subsample and 16.7 percent of the overlap subsample showed a significant increase in facial height, significant eruption of maxillary incisors, and no change in overbite. The contact subsample had no significant posttreatment changes. Possible reasons for the posttreatment instability in the openbite subsample are proposed.
This prospective clinical study was undertaken to analyze adult skeletodental changes induced by a reverse curve mushroom archwire during the initial stage of treatment. Lateral cephalograms from before treatment and immediately after bite opening were evaluated from 8 female adult patients who were undergoing lingual orthodontic treatment. Before treatment the patients had a mean overbite of 3.9 mm. Six linear and 5 angular measurements were selected for cephalometric analysis. The mean change in the cephalometric parameters was subjected to paired t-tests to determine whether the change was significant. There was a highly significant overbite reduction (-1.9 mm, P < .001) leaving a postintrusion overbite of 2.0 mm. The lower incisors were intruded 1.5 mm (P < .001) and the lower incisor edge was in an approximately stable sagittal position (L1 to NPg = -0.2 mm, NS). Some lower incisor proclination (L1 to MP = 1.2 degrees) was seen, which was not of significance. The mandibular molars were not significantly extruded. After bite opening the mandibular plane angle was not significantly altered. Consequently, the lower anterior face height was not significantly increased. The results of this study revealed that the use of reverse curve mushroom archwire is capable of intruding the lower incisors with minimal side effects on the posterior teeth.
This study evaluates the longitudinal changes in occlusal dimensions in young adults. The sample was composed of 27 individuals (13 male and 14 female individuals) who presented dental Class I and normal occlusion, according to the inclusion protocol. All teeth were present except for the third molars. The mean age of the subjects was 21 years and two months initially and 28 years and four months at the end of the observation period. The measurements collected in both arches were overbite, overjet, intercanine and intermolar distances, irregularity index, and perimeter. All measurements were taken from study dental casts by a calibrated operator, using a digital caliper. The paired t-test was used to evaluate the changes, using the difference between the initial and final mean measurements. Data indicated that the overbite increased 0.39 mm, the incisor irregularity increased 0.38 mm in the upper arch and 0.54 mm in the lower arch, and the arch perimeter decreased 0.67 mm in the upper arch and 0.71 mm in the lower arch (P > .05). The other measurements did not show significant changes. No sexual dimorphism was observed. It could be concluded that occlusal dimensions change throughout adult life. In the sample studied, changes were statistically significant for overbite, incisors irregularity, and arch perimeter after a mean period of seven years and two months. These changes can be observed in both sexes.
To compare normal overbite, deep bite and open bite cases with clinically healthy temporomandibular joints (TMJ) regarding the difference between condylar positions in centric relation (CR) and habitual or centric occlusion (CO), condylar paths and radiographic findings of condylar appearance in order to establish normative data. Three study groups of normal overbite, deep bite and open bite cases consisted each of 30 subjects with no detectable clinical signs of temporomandibular disorder. The CR-CO differences and axiographic tracings were recorded using the School Artikulator of Mack (SAM) diagnostic system. Condylar shape was evaluated on panoramic radiographs. The CR-CO differences were greater in the vertical plane in open bite cases, and direction of movements from CR to CO showed great variability. Open bite cases had significantly shorter condylar paths. Radiographic findings exhibited that 23% of the total sample showed evidence of erosion and 83% evidence of flattening of condyles. The erosion rates were higher in the open bite group, but flattening was seen more often in the deep bite group. Results of this study showed that open bite cases show larger vertical CR-CO slides and, shorter protrusion paths than normal and deep overbite cases. The radiographic appearance of condyles in non-patients may also differ significantly according to vertical incisor guidance type. Deep bite cases demonstrated a higher incidence of condylar flattening. This study indicates that the clinician should be paying special attention to the TMJ status of open bite patients.
OBJECTIVES: To assess tooth and arch dimensions, occlusal relationships and the presence of spacing or crowding in primary dentition of Jordanian children. STUDY DESIGN: A list of 10 kindergartens was randomly selected in the governate of Irbid, Jordan. A total of 1048 children (2.5-6 years old) with complete primary dentitions were examined for occlusal relationships in three planes, and the presence of spacing or crowding. Of those, study casts were taken for 87 randomly selected 4-5-year-old children (39 girls, 48 boys). Measurements of tooth and arch dimensions were made using electronic digital sliding callipers. RESULTS: In general, males had larger mesiodistal tooth width and larger arch dimensions. Bilateral mesial step molar relationship was found in 47.7% of children followed by bilateral flush terminal molar relationship in 37% and bilateral distal step in 3.7%. Asymmetric right/left molar relationship was found in 11.6% of children examined. Class I canine relationship was found in 57% of children, followed by Class II canines in 29% and Class III canines in 3.7%. Fifty per cent of children examined had Class I incisors, 24.7% had Class II Division 1, 13.5% had Class II Division 2 and 11.8% showed reversed overjet. Ideal overbite was seen in 44.3% of children, reduced overbite in 21.8%, increased overbite in 28.2% and 5.7% had anterior openbite. Buccal crossbite was seen in 7% of the sample. Generalized spacing was found in 61.8% and 61.1% of children in the upper and lower arches, respectively. Anthropoid spaces were found in 70% of the upper arches and in 51% of the lower arches. CONCLUSIONS: Males had larger tooth/arch dimension than that of females in the primary dentition stage. Mesial step molar relationship was found in 47.7% of the subjects followed by flush terminal molar relationship in 37%. The majority of children examined had spaced primary dentition.
The purpose of this study was to use the Peer Assesment Rating (PAR) index score to evaluate the treatment and posttreatment changes of Class III patients treated by protraction facemask. The sample consisted of 20 Chinese children, 6 to 11 years old, with Class III skeletal malocclusion who had been treated with maxillary expansion and a protraction facemask. The average treatment time was 8.2 months, followed by 1 year of retention with a Class III functional appliance. Study casts were taken pretreatment (T1), posttreatment (T2), 1 year follow-up (T3), and 2 years follow-up (T4). After treatment, PAR scores were calculated for each time period. Differences among the 4 time periods were analyzed with the Wilcoxin matched-pairs test. Significant reductions in PAR scores were found at T2 (56%), T3 (70%), and T4 (63%) compared with T1. Immediately posttreatment (T2), 17 (85%) of 20 patients had improved PAR scores by a reduction of at least 30%. Reductions were caused primarily by correction of the anterior crossbite. One year after treatment (T3), further reductions in PAR score were noted (P <.01) as a result of better alignment of the anterior segment, improvement of the buccal occlusion, and overbite and midline corrections. Two years after treatment (T4), PAR scores were higher than at the previous time period. The increases were due to relapses in overjet (4 of 20 patients), overbite, and centerline corrections. These results indicate that significant reductions in the severity of Class III malocclusion can be achieved with early orthopedic facemask treatment. In most cases, further improvement in the PAR score can be expected 1 and 2 years after treatment. In a few patients, the benefits of early treatment are negated by relapses in overjet, overbite, and centerline corrections during the follow-up period.
Although many improvements have been made in orthodontic surgical procedures for mandibular retrognathism, relapse continues to occur. This study was designed to compare the stability of rigid and nonrigid fixation between 2 groups of patients who had undergone mandibular advancement surgery via sagittal split ramus osteotomy. Retrospective cephalometric measurements were made on 54 randomly selected orthognathic surgical patients. The patients, 7 males and 47 females, were divided into 2 groups: 28 patients stabilized by means of rigid fixation and 26 patients fixated with interosseous wires. The age of the patients ranged from 15.3 to 49.7 years. Lateral cephalograms were used to evaluate each patient at 3 distinct intervals: 7.0 +/- 2.0 days before surgery (T1), 34.4 +/- 15.0 days postsurgery (T2), and 458 +/- 202 days after sagittal split osteotomy (T3). Eighteen linear and angular measurements were recorded and differences between the 3 time periods were evaluated. Statistical analyses were performed to assess the differences in the 2 fixation types between and within each group at different time intervals. The following measurements showed statistically significant skeletal relapse over time, for the P value.0028: Co-Go, ANS-Xi-Pm, IMPA, overbite, and overjet. The remaining variables showed no statistically significant relapse. The only measurement that showed a statistically significant group difference between T1 and T2 was DC-Xi-Pm. Results of the study led to the following conclusions: there was statistically significant relapse in mandibular length, lower anterior face height, mandibular arc, lower incisor inclination, overbite, and overjet in each group, regardless of the type of fixation. The potential was greater for relapse in patients stabilized with transosseous wiring. Although multifactorial, relapse in overbite and overjet may be a combination of skeletal and dental changes. (Am J Orthod Dentofacial Orthop 2000;118:397-403).
This study examined the accuracy and reliability with standardized definitions among 30 orthodontists in assessing different aspects of malocclusion from the study casts of 10 patients. Previous studies have indicated a lack of consistency among orthodontists in describing malocclusions. The diagnostic subcategories measured in this study included maxillary and mandibular crowding, overbite, overjet, and a modified molar, premolar, and canine Angle classification. Intraclass correlations indicated that the reliability of all parameters was good (intraclass correlation > 0.80), with overbite being the most reliable (0.98) and maxillary crowding and canine classification somewhat less reliable (0.89 and 0.87, respectively). Among Angle classifications, molar classification was the highest (0.95), followed by premolar (0.92) and canine (0.87). This study also measured the accuracy of the orthodontists' measurements compared with established true values (validity). T tests indicated that mandibular arch crowding and overbite were not statistically different from the true values. Overjet and molar classification were assessed very close to the true values. Although premolar and canine classifications were statistically different from the true values, they were within a one-eighth cusp of the true value (a clinically insignificant difference). The orthodontists consistently overestimated the amount of maxillary arch crowding or spacing. The results suggest that high reliability and reasonable accuracy can be expected for assessing study casts when using standardized definitions for the diagnostic subcategories.
The aim of this study was to investigate growth and treatment changes in patients with Class II Division 1 malocclusion treated with a combined headgear-activator appliance. The sample consisted of 20 consecutive male patients treated with headgear-activator. Their compliance was checked after 2 months of treatment, and 3 patients dropped out. Lateral cephalograms, obtained 6 months before treatment, at the start of treatment, after 6 and 12 months of treatment, and 24 months after treatment, were analyzed by the method of Pancherz. The results disclosed that during growth, on average, overjet, molar relationship, and jaw-base relationship improved, and the mandibular incisors became retruded; the changes were statistically significant over a 2-year period. There was no significant change in the overbite. During the 12 months of treatment, there was no maxillary forward growth, and the jaw relationship improved (P <.001) because of forward growth of the mandible (P <.001). The molar relationship and the overbite improved (P <.001). Significant treatment effects included reduction in overjet (P <.001) and overbite (P <.01), and improvement of jaw-base (P <.05) and molar (P <.001) relationships. There was significant restraint of maxillary forward growth (P <.05). The eruption of the maxillary incisors and molars was restrained (P <.05). The average basic growth pattern in Class II Division 1 malocclusion resulted in small favorable changes in overjet, molar relationship, and jaw-base relationship. The main effect of the headgear-activator appliance was a favorable dental change, limited to restraint of maxillary forward growth but not affecting the vertical dimension.
A prospective clinical trial was conducted to determine the skeletal and dental contributions to the correction of overjet and overbite in Class III patients. Thirty patients (12 males and 18 females with a mean age of 8.4 +/- 1.7 years) were treated consecutively with protraction headgear and fixed maxillary expansion appliances. For each patient, a lateral cephalogram was taken 6 months before treatment (T0); immediately before treatment (T1); and 6 months after treatment (T2). The time period (T1-T0) represented changes due to 6 months of growth without treatment; (T2-T1) represented 6 months of growth and treatment. Each patient served as his/her own control. Cephalometric analysis described by Björk (1947) and Pancherz (1982a,b) was used. Sagittal and vertical measurements were made along the occlusal plane (OLs) and the occlusal plane perpendicular (OLp), and superimposed on the mid-sagittal cranial structure. The results revealed the following: with 6 months of treatment, all subjects were treated to Class I or overcorrected to Class I or Class II dental arch relationships. Overjet and sagittal molar relationships improved by an average of 6.2 and 4.5 mm, respectively. This was a result of 1.8 mm of forward maxillary growth, a 2.5-mm of backward movement of the mandible, a 1.7-mm of labial movement of maxillary incisors, a 0.2-mm of lingual movement of mandibular incisors, and a 0.2-mm of greater mesial movement of maxillary than mandibular molars. The mean overbite reduction was 2.6 mm. Maxillary and mandibular molars were erupted occlusally by 0.9 and 1.4 mm, respectively. The mandibular plane angle was increased by 1.5 degrees and the lower facial height by 2.9 mm. Individual variations in response to maxillary protraction was large for most of the parameters tested. Significant differences in treatment changes between male and female subjects were found only in the vertical eruption of mandibular incisors and maxillary and mandibular molars. These results demonstrate that significant overjet and overbite corrections can be obtained with 6 months of maxillary protraction in combination with a fixed expansion appliance.
A prospective study was undertaken to investigate the relationship between various measured pre-treatment parameters and the reduction in overjet achieved when using a twin block functional appliance. Forty-three subjects were fitted with a twin block functional appliance, and a number of pre-treatment clinical and radiographic morphological features were recorded. The functional appliance wear was monitored for 6 months and any individual who did not co-operate with wear was excluded from the subsequent analysis. Multiple regression analysis with stepwise inclusion was used to relate the percentage reduction in overjet achieved by functional appliance wear to any of the pre-treatment parameters. The data from 22 individuals was included in the final analysis. The overbite and SNB angle were the most strongly related variables to percentage reduction in overjet. These were then used to construct a predictive equation for the expected percentage reduction in overjet: Percentage reduction in overjet in 6 months = 132 + 4.9x1 - 1.4x2, where x1 = overbite and x2 = SNB. The pre-treatment overbite was, in isolation, the most influential feature in predicting the percentage of overjet reduction.
Early interceptive treatment for the elimination of factors inhibiting dental arch development and mandibular and maxillary growth is applied varyingly by orthodontists, possibly because there is little scientific evidence that such interventions are of actual benefit. The aim of this study was to determine specific factors for treatment need in the early mixed dentition period in order to obtain basic data to support early intervention. The study was part of a larger survey of 8768 children aged between 6 and 17 years. From this sample, 1975 children aged between 6 and 8 years were used to estimate the prevalence of malocclusions using the Index of Orthodontic Treatment Need (IOTN) during the early mixed dentition period. The results showed that deep overbite and overjet, both more than 3.5 mm, were the most frequent discrepancies, affecting 46.2 and 37.5 per cent of patients, respectively. An anterior open bite was registered in 17.7 per cent, crossbite in 8.2 per cent, and a reverse overjet in 3.2 per cent. A tooth width to arch length discrepancy was recorded in 12 per cent of teeth in the upper arch and in 14.3 per cent in the lower arch. The proportion of children estimated using the Dental Health Component of the IOTN to have a great or very great treatment need (grades 4 and 5) was 26.2 per cent. The higher values of treatment need during the mixed dentition period may account for temporary changes in the dentition and for the discrepancy in overjet and overbite. These discrepancies will be compensated in part during mandibular growth and development of the dental arch. Nevertheless, the findings indicate the early development of progressive malocclusion symptoms which are evidenced in the IOTN and concur with the acronym 'MOCDO' hierarchy (missing, overjet, crossbite, displacement, overbite). This early formation of progressive symptoms inhibiting or disturbing mandibular or maxillary growth or the development of the normal dental arch, i.e. crossbite, reverse overjet and increased overjet with myofunctional disorders, should be treated at an early stage.
The present study prospectively assesses the skeletal stability in a consecutive series of Binder syndrome patients (n = 7), aged 16 to 20 years, who underwent LeFort I osteotomy fixed with miniplates and the associated morbidity. All patients underwent a one-piece LeFort I osteotomy fixed with four miniplates in conjunction with orthodontic treatment during the period of 1986-1992. Five of seven patients underwent iliac grafting to their deficient premaxilla and interpositionally at their osteotomy sites. Six of seven patients underwent bone graft augmentation of their deficient nose (four costochondral, one cranial, and one iliac). Serial cephalometric radiographs were taken at standard intervals after surgery (1 week, 6-8 weeks, 1 year). Horizontal, anterior vertical, and posterior vertical directional changes were then measured at each interval. With the radiographs superimposed, the amount of change was measured by the method of anatomic best fit. The 1-year postoperative cephalograms also were assessed for overjet and overbite. The medical records were reviewed for morbidity. Each patient had a complete set of longitudinal records. Follow-up ranged from 1.5 to 5.5 years at the close of the study. Perioperative morbidity was unremarkable, other than one patient whose cranial bone graft dehiscence through the nasal skin required regrafting. The mean (effective) maxillary advancement for the group was 6.0 mm, with 5.9 mm maintained 1 year later. The mean anterior vertical change of the maxilla was 4.2 mm, with 3.1 mm maintained; whereas the mean posterior vertical change was 2.8 mm, with 2.2 mm maintained. All patients maintained a positive overjet and overbite at 1 year. In our series, a staged reconstructive approach for Binder syndrome was carried out in the teenage years and included orthodontic treatment, orthognathic surgery, and nasal augmentation. The extent of skeletal relapse of the LeFort I osteotomy fell within a range that could be managed effectively to maintain a long-term positive overjet and overbite.
In a sample of 30 partially edentulous subjects, provided with an immediate complete upper denture and a partial lower denture and followed for 2 years, a correlation analysis was performed between facial morphology, as measured by lateral head films, and EMG peak mean voltages of the anterior temporal and masseter muscles when clenched and during swallowing and chewing, and of the lip muscles during swallowing. At the pre-treatment stage, when the patients occluded on a residual anterior dentition, correlations between facial morphologic characteristics and peak mean voltages of the jaw closing muscles indicated stronger muscle activity in individuals with a square facial type. No significant associations were observed between muscle activity and the age of the subjects, which ranged from 36 to 71 years. After placement and use of the dentures a significant forward-upward rotation of the mandible with a decrease in overbite occurred, as a result of resorption of the edentulous maxillary ridge. At the 1 year stage of denture use, the elevator activity showed no significant correlations with facial morphology. On the other hand, negative correlations were observed especially between the anterior temporal activity and anterior overbite. Similar negative correlations were observed for the lip activity during swallowing, especially of the upper lip. These findings suggest occlusal contact between the incisors during the various functions in subjects with a small overbite. The findings further suggest that the anterior temporal and the upper lip muscles are sensitive to changes in anterior occlusal relations of the dentures.
This study assessed the temporomandibular joint of 34 children with spastic quadriplegic cerebral palsy for contractures to determine whether joint abnormalities were related to oral-motor dysfunction. Subjects were found to have restrictions in mandibular range of motion, increased overjet and decreased overbite. Increased overjet corresponds to retrognathia and decreased overbite relates to fixed posterior rotation of the mandible. The severity of many of these abnormalities correlated with the severity of oral-motor dysfunction. Abnormalities in overbite were particularly significant. The authors conclude that temporomandibular joint contractures in this population are related to problems in oral-motor function. It is hoped that further research in this area will lead to new therapies for children with feeding and swallowing problems.
The aim of this study was to investigate the relationship between occlusal factors (overjet, overbite, Angle's Classification of molars and cuspids, the relationship of the primary molars, openbite, lateral openbite, scissorbite and crossbite) and bruxism in permanent and mixed dentition in Turkish children. For this reason 182 children with mixed dentition and 212 children with permanent dentition were included in this study. Occlusal conditions were examined clinically and bruxism was assessed by using interview and questionnaires. Z Test was used to compare the results. It was found that in both dentitions some occlusal factors related with bruxism (overjet > 6 mm, overbite > 5 mm, negative overjet, openbite in permanent dentition; overjet > 6 mm, overbite > 5 mm, scissorbite, anterior-posterior multiple teeth crossbite, Angle Class I occlusion in mixed dentition.
The purpose of the study was to evaluate the longitudinal relationship between incisal wear of central incisors and the size of vertical overbite (OB) and horizontal overjet (OJ). Stone casts of 51 subjects were used for the determinations. Casts were obtained when the subjects were 15 and 27 years old. Statistical analysis was performed with the t test for paired samples, the chi-square test of association. Pearson's product moment correlation coefficient, and Spearman's rank correlation coefficient. Both overbite and overjet diminished after 12 years, and incisal wear increased. It was concluded that increase in age, incisal wear, vertical overbite and incisal occlusion (OB/OJ) are clinical predictors of wear of maxillary and mandibular central incisors in adolescents.