Changes In Overbite Research Articles

Rigid versus wire fixation for mandibular advancement: Skeletal and dental changes after 5 years

The bilateral sagittal split osteotomy (BSSO) is the most common surgical procedure for the correction of mandibular retrognathism. Commonly, the proximal and distal segments are fixated together with either wire or rigid screws or plates. The purpose of this study was to compare long-term (5 years) skeletal and dental changes between wire and rigid fixation after BSSO. In this multisite, prospective, randomized clinical trial, the rigid fixation group received three 2-mm bicortical position screws, and the wire fixation group received inferior border wires and 6 weeks of skeletal maxillomandibular fixation with 24-gauge wires. Cephalometric films were obtained 2 weeks before surgery and at 1 week, 8 weeks, 6 months, 1 year, 2 years, and 5 years after surgery. Linear cephalometric changes were referenced to a cranial base coordinate system. Before surgery, both groups were comparable with respect to linear and angular measurements of craniofacial morphology. Both groups underwent similar surgical changes. Skeletal and dental movements occurred in both groups throughout the study period. Five years after surgery, the wire group had 2.2 mm (42%) of sagittal skeletal relapse, while the rigid group remained unchanged from immediately postsurgery. Surprisingly, at 5 years, both groups had similar changes in overbite and overjet. This was attributed to dental changes in the maxillary and mandibular incisors. Although rigid fixation is more stable than wire fixation for maintaining the skeletal advancement after a BSSO, the incisor changes made the resultant occlusions of the 2 groups indistinguishable. (Am J Orthod Dentofacial Orthop 2002;121:610-9)

Long-term stability of the leveling of the curve of Spee

The aim of the study was to investigate whether the orthodontic leveling of the curve of Spee is a treatment procedure with a stable result on a long-term basis. Measurements were made on the plaster casts of 149 orthodontically treated patients (57 males and 92 females). The mean age before treatment was 12.8 years (range, 8-25 years). Study casts were taken before treatment (T1), at the completion of orthodontic therapy (T2), and 6.7 years (mean) posttreatment (T3). Inclusion criteria were no extractions, all Angle classifications except Class III malocclusions, and all permanent teeth fully erupted except second and third molars. The curve of Spee and the irregularity index were measured on standardized digital photographs of the casts. Overjet and overbite were assessed with a ruler. Changes in the curve of Spee were correlated with changes in irregularity index, overjet, and overbite from T1 to T3. The following results were noted: (1) leveling of the curve of Spee is a relatively stable treatment procedure compared with a return of incisor crowding and deepening of the bite; (2) neither the initial depth of the curve of Spee nor the initial irregularity index is an indicator for the amount of relapse; (3) the amount of leveling is not correlated with the relapse of the 4 tested parameters (curve of Spee, irregularity index, overjet, and overbite); and (4) there is a mild correlation between the relapse of the curve of Spee and the relapse of the irregularity index, overjet, and overbite. According to the results of the study, leveling the curve of Spee during orthodontic treatment seems to be very stable on a long-term basis; it was weakly correlated with the other variables tested. (Am J Orthod Dentofacial Orthop 2002;121:266-72)

Cephalometric and physiologic predictors of the efficacy of an adjustable oral appliance for treating obstructive sleep apnea.

The purpose of this study was to investigate whether any physiologic or cephalometric parameters could be used to predict the efficacy of an adjustable mandibular advancement appliance for treating obstructive sleep apnea (OSA). Forty-two male and 5 female patients with OSA were recruited on the basis of baseline polysomnography with a documented Apnea and Hypopnea Index (AHI) greater than 15 per hour. Repeat polysomnography was performed with the appliance in place. Baseline cephalometry was performed for each patient, and follow-up cephalometry was completed for 19 of the subjects. The subjects were divided into 3 groups on the basis of the degree of change in the AHI with oral appliance therapy: good response (> 75% decrease in AHI), moderate response (25% to 75% decrease in AHI), and poor response (< 25% decrease in AHI). Patients with a good response were younger and had smaller upper airways. In a linear regression analysis, the change in AHI (%) was associated with physiologic (age and body mass index), cephalometric (overjet, height of the maxillary molars, vertical height of the hyoid bone), and airway variables. However, changes in either overbite or overjet were not related to changes in any of the polysomnographic variables for the 19 subjects. A stepwise regression analysis revealed a better treatment response with the adjustable mandibular advancement appliance in patients who were younger and had a lower body mass index, a longer maxilla, a smaller oropharynx, a smaller overjet, less erupted maxillary molars, and a larger ratio of vertical airway length to the cross-sectional area of the soft palate.

A new method of evaluating posterior occlusion and its relation to posttreatment occlusal changes.

The purpose of this study was to assess the relationship between posterior occlusion and posttreatment changes in other occlusal variables. Pretreatment (T1), posttreatment (T2), and postretention (T3) records were obtained for 49 Class I (n = 23) and Class II (n = 26) extraction cases. Overbite, overjet, mandibular incisor irregularity, right and left molar deviations, midline deviation, and mandibular arch length were measured, and occlusal registrations were made of each set of dental casts. The proximity of posterior occlusal surfaces was measured as the contact or near-contact areas at or below 300 microm thickness, based on the optical densities of scanned images of the posterior occlusal registrations. The treatment changes for overbite, overjet, right and left molar deviation, and arch length were significantly greater in the Class II group, and the reductions in incisor irregularity were greater in the Class I group. No other class differences were found. Overbite, overjet, and incisor irregularity increased after treatment, and arch length continued to decrease, with no significant class differences. Contact and near-contact areas at or below 300 microm constituted 7% of the functional occlusal table for both classes at the end of treatment, having decreased significantly in both groups (21% in Class I and 29% in Class II) during treatment. Because contact and near-contact areas increased in some patients and decreased in others, there were no significant posttreatment changes. Negative correlations were found between contact and near-contact areas at T2 and changes in overjet from T2 to T3, and between contact and near-contact areas at T3 and changes in overbite from T2 to T3. No relationships were found between posterior contact and near-contact area and incisor irregularity. We concluded that (1) the area of actual and near contacts at or below 300 microm decreased significantly with treatment, indicating that, despite excellent treatment results by conventional standards, the proximity of posterior occlusal surfaces lessened; (2) the proximity of the posterior occlusal surfaces should not be expected to increase posttreatment; (3) posttreatment contact and near-contact areas may be factors in overbite and overjet stability; and (4) posttreatment contact and near-contact areas are not related to incisor irregularity.

Orthodontic side-effects of mandibular advancement devices during treatment of snoring and sleep apnoea.

The aims of this study were to investigate possible orthodontic side-effects following the use of mandibular advancement devices (MAD) in adults with snoring and sleep apnoea. A second objective was to analyse the effect of the appliance design. Seventy-five patients treated with MAD and 17 reference patients were studied at follow-up after 2.5 +/- 0.5 years. In the test group, 47 patients were provided with soft elastomeric devices, while the remaining 28 patients received hard acrylic devices. The treatment induced a change in overjet of -0.4 +/- 0.8 mm (mean +/- SD) and a change in overbite of -0.4 +/- 0.7 mm (mean +/- SD). These changes were larger than those found in the reference group (P < 0.01). The odds ratio (OR) for the largest quartile of reduction in overjet was 3.8 in patients using hard acrylic devices compared with those using soft elastomeric devices (P < 0.05). A large reduction in overjet in patients using the hard acrylic devices was unrelated to the degree of mandibular protrusion by the device. The OR for a large reduction in overjet in patients using the soft elastomeric devices with a protrusion of 6 mm or above was 6.8 compared with smaller mandibular protrusions (P < 0.05). The results indicate that the orthodontic side-effects are small during the treatment of adult subjects with MAD for snoring and sleep apnoea, especially in patients using soft elastomeric devices with mandibular protrusions of less than 6 mm. The follow-up of patients treated with MAD is recommended, as individual patients may experience marked orthodontic side-effects.

Stability of anterior openbite correction with multiloop edgewise archwire therapy: A cephalometric follow-up study

Successful treatment of anterior openbite malocclusion is considered one of the most challenging areas in orthodontics. This study was designed to evaluate the treatment effects of the multiloop edgewise archwire therapy in openbite correction and to investigate the stability of correction during a 2-year follow-up period. The subjects consisted of 55 white patients who presented with anterior openbite. The subjects were divided into 2 groups: the growing group included 29 patients and the nongrowing group included 26 patients. The lateral cephalograms were analyzed for skeletal, esthetic, and dentoalveolar changes. Analysis of the pretreatment and posttreatment cephalometric radiographs revealed that the overbite increased an average of 4 mm in both the growing and the nongrowing groups. Analysis of the posttreatment and follow-up cephalometric radiographs proved that the treatment results obtained by this therapy were very stable. The changes in overbite during the 2-year follow-up period were not significant. (Am J Orthod Dentofacial Orthop 2000;118:43-54)

Supine Cephalometric Analyses of an Adjustable Oral Appliance Used in the Treatment of Obstructive Sleep Apnea.

OBJECTIVE: To investigate the effects of the Klearway(TM) appliance on the upper airway in patients with obstructive sleep apnea (OSA) in the supine position. METHODS: Sixteen subjects (12 males and 4 females) were recruited on the basis of baseline polysomnography with a documented Apnea and Hypopnea Index (AHI) >15 per hour. A second overnight sleep study was performed for each subject with the appliance in place. Baseline supine cephalometry was performed for each subject before the initial insertion of the appliance, and follow-up supine cephalometry was undertaken with the appliance in place. RESULTS: The polysomnographic variables improved significantly, and the mean changes in overbite and overjet were 5.15 mm and 6.26 mm after insertion of the Klearway(TM) appliance. The supine sagittal cross-sectional areas of the pharynx and the tongue significantly increased, while the linear distance from the hyoid position to the mandibular plane or the RGN-C3 line significantly decreased after insertion of the appliance. The ratio of the vertical pharyngeal length to the sagittal cross-sectional area of nasopharynx or tongue decreased significantly. When the subjects were evaluated on the basis of the after-insertion AHI, the group with good response (n = 11) was found to be significantly younger than the group with the poor response (n = 5). Similarly, the good responders revealed less prominent chins, larger tongue heights, and an increase in hypopharyngeal sagittal cross-sectional area after insertion of the appliance. There was a significant correlation between the improvement in AHI (%) and the supine middle airway space (r = -0.52, p < 0.05). CONCLUSION: The mechanical effect of the Klearway(TM) appliance on the upper airway and the stabilization of jaw posture may be important determinants of the efficacy of the appliance.

Evaluation of the vertical holding appliance in treatment of high-angle patients

Controlling the vertical dimension of high-angle patients without the benefit of compliance can be a challenging aspect of orthodontic treatment. This retrospective study examines the skeletal and dental effects of a modified transpalatal bar, dubbed the vertical holding appliance (VHA), which was used in an attempt to control the vertical dimension of high-angle patients. Two cephalometrically similar groups of high-angle patients (16 patients each) were compared to determine advantages from using the VHA. Group I (n = 16, pretreatment age 13.4 ± 1.6 years) was treated with 4 premolar extractions in conjunction with the VHA cemented in place for 17.4 ± 6.1 months. Group II (n = 16, pretreatment age 13.4 ± 1.9 years), which was matched for age and pretreatment skeletal pattern, was treated with the Tweed technique and 4 premolar extractions. Lateral cephalometric radiographs were taken before the placement of the VHA, as well as at the end of treatment. The results showed that although y-axis increased significantly in group II ( P < .05), it remained the same in group I. Within group I, the Frankfort mandibular plane angle and gonion gnathion/sella nasion angle decreased, whereas both of these values increased in group II. However, these changes were statistically insignificant. Lower anterior face height increased more in group II than in group I ( P < .05). The percentage of lower anterior face height to total anterior face height decreased in group I, whereas it increased in group II. The difference between the 2 groups was determined to be significant ( P < .01). Eruption of the maxillary first molar within group I was less than in group II. No significant differences were found between groups I and II for changes in overbite. (Am J Orthod Dentofacial Orthop 2000;117:700-5)

Vertical components of overbite change: A mathematical model

The purpose of this study was to better understand the multidimensional nature of overbite changes that occur during adolescence. The study used longitudinal cephalograms of 181 untreated children (102 males, 79 females) taken at ages 10 and 15. Four major components that directly affect overbite were measured: (1) maxillary vertical displacement, (2) mandibular vertical displacement, (3) upper incisor vertical change within the bone, (4) lower incisor vertical change within the bone. Cranial base, maxillary, and mandibular superimpositions were performed for each subject to assess the vertical changes that occurred in these 4 components and to assess overbite. A multiple regression analysis was used to develop a mathematical model describing the relationships of these components to changes in overbite. The model was validated with an independent subsample and a comparison of subjects whose overbites decreased and those whose overbites increased. The results showed that overbite changed minimally (0.2 mm) over the 5-year period; variation ranged from a 2.4 mm decrease to a 5.6 mm increase. The regression model indicated that the mandibular skeletal changes were twice as important as the mandibular dental changes and about 2.5 times as important as the maxillary changes in effecting overbite change. Within the mandibular skeletal component, vertical growth was more important than mandibular rotation in determining overbite change. The model demonstrated that a multivariate approach is necessary to understand overbite changes. More effective orthodontic treatment might be achieved by focusing on the primary components effecting overbite change, especially those with the greatest potential for therapeutic modification. (Am J Orthod Dentofacial Orthop 2000;117:486-95)

Changes in overbite and face height from 5 to 45 years of age in normal subjects.

The purpose of this study was to evaluate changes in overbite over a 40-year span, and to relate these changes to those occurring in vertical skeletal facial relationships. Lateral cephalograms of 20 males and 15 females from the Iowa Facial Growth Study were evaluated at ages 5, 10, 15, 25, and 45 years. Correlation coefficients were computed to determine the relationship between overbite and various skeletal parameters. Analysis of variance and Duncan's multiple-range test were used to compare various periods of growth. Statistical significance was predetermined at the 0.05 level of confidence. No significant correlations were found between the absolute values of overbite and the vertical skeletal parameters in either males or females. Incremental changes in overbite during four growth periods were compared with changes in various vertical parameters and only a few significant correlations were found. In males, the change in overbite was significantly correlated with changes in N-Ans'/N-Me and MP:SN during the 10-to-15 year growth period. In females, the change in overbite was significantly correlated with changes in N-Ans'/N-Me% during the 5-to-10-year period and also with change in Ar'-Go/S-Go% during the 15-to-25-year period. In general, changes in overbite with age are difficult to predict from the initial overbite in the deciduous or mixed dentitions. On the other hand, evaluation of individual curves shows that males who initially had the least amount of overbite maintained that trend during the later stages of development. Although overbite changes were significantly associated with changes in some vertical parameters, the associations were not of clinical significance for predictive purposes, and overbite changes are probably dependent on concurrent changes in the growth of the alveolar processes.

Effects of a myofunctional appliance on orofacial muscle activity and structures.

The aim of the study was to examine the effect of an oral shield treatment on orofacial muscle activity and facial morphology in children with lip and/or tongue dysfunction. The sample consisted of 7 girls and 2 boys, 7 to 12 years old. EMG recordings with and without the shield in situ were obtained when the shield was placed, and 3, 6, and 12 months later. Lateral cephalograms were obtained at the initial and 1-year stages. The lip muscles showed dominant activity when the subjects were sucking on an empty straw and during swallowing; this was strongest during the first 3 months. The mentalis, buccinator, and digastric muscles generally showed weaker activity. The anterior temporal muscle showed dominant activity during maximal clench, but after the 3-month stage a significant decrease was noted. After 1 year of treatment, no significant changes in overjet or overbite were observed. Most of the craniofacial growth changes were normal for the age group. The results indicate that treatment with an oral shield caused a decrease in orofacial muscle activity during oral functions. Although there was a slight average retraction of the maxillary incisors, the change in position was not statistically significant.

下顎枝矢状分割術を受けた下顎前突患者における顎顔面形態の長期変化とこう合の安定性

The purpose of this study was to investigate the long-term dentofacial changes following sagittal splitting ramus osteotomy in mandibular prognathism patients and to clarify morphologic factors relevant to the stability of occlusion during the retention period.Lateral cephalograms of 19 patients (5 males and 14 females), observed for more than three years after the end of active treatment, were analyzed for evaluation of dentofacial changes. The materials were obtained at five stages: before treatment, immediately before surgery, at removal of intermaxillary fixation, at the end of active treatment and at the last. Dentofacial changes were analyzed and compared between the stages.The results were as follows:1. During the preoperative orthodontic treatment, the mandibular incisors were inclined labially and menton was displaced downward.Menton was moved backward 11.1mm on average by surgery. The maxillary and mandibular incisors moved lingually and elongated during intermaxillary fixation.During the postoperative orthodontic period, menton was displaced forward and upward (average; anteriorly 2.6mm, superiorly 0.6mm). A correlation was found between the amounts of mandibular setback and forward displacement of menton. The maxillary incisors were inclined labially.During retention, the menton was displaced downward and mandibular incisors were slightly inclined labially.2. Overjet and overbite tended to decrease slightly during the retention period. At the end of treatment, an acceptable occlusal relationship in the anterior region was maintained in most cases. Two patients showed edge-to-edge occlusion and one of them showed open bite.No correlation was found between the dentofacial morphology before treatment and changes in overjet or overbite. A significant correlation was found between the amount of mandibular setback and the decrease in overbite. Vertical changes in menton and labial inclination of mandibular incisors during the retention period play a significant role in the occlusal stability after orthognathic surgery.

The effect of extraction of four second permanent molars on the incisor overbite.

Changes in incisor overbite were compared in 33 subjects who had four second molars extracted and 33 untreated subjects. There was an average increase in overbite of 0.7 mm in the extraction group, significantly different from an average decrease of -0.8 mm in the control group. The tendency to increase in overbite was greater in subjects whose presenting overbite was already reduced. The mechanism responsible for overbite reduction appeared to be a slight distal movement of the dentition, with retroclination of incisors and increase in inter-incisal angle.

Maturation of untreated normal occlusions

The dental casts of 65 untreated normal occlusions were evaluated to determine the nature and extent of the developmental maturation process of the normal dentition. Six dental parameters were examined in the mixed dentition (9 to 10 years), early permanent dentition (12 to 13 years), and early adulthood (19 to 20 years). Results showed decreases in arch length and intercanine width; minimal overall changes in intermolar width, overjet, and overbite; and increases in incisor irregularity. Females showed more severe changes than males. The individual changes found were not correlated to changes in any of the other parameters measured. No associations or predictors of clinical value were found. The changes found in a sample of untreated normals were similar in nature but lesser in extent than postretention changes found in a sample of treated cases.

Overbite and face height in 44 male subjects with class I, class II/1 and class II/2 occlusion

Overbite, total face height and lower face height were measured on lateral cephalometric radiographs of subjects with Class I, Class II/I and Class II/2 occlusions at age 10 and 15 years, recorded at visit 11 and visit 21 of a series respectively. Analysis of variance showed intra- and inter-observer error to be small within the context of the parameters used. Overbite was largest and face height smallest in the Class II/2 Group and the reverse in the Class I Group with the values for the Class II/I Group falling in between. Correlation coefficients revealed a negative relationship between face height and overbite, and change in face height and overbite, being more significant in respect of lower face height than total face height.

Spontaneous Changes in the Incisor Relationship following Extraction of Lower First Permanent Molars

The spontaneous changes in overbite, overjet and incisor inclinations during the first year following extraction of both lower first permanent molars were investigated in 43 (19M, 24F) patients whose ages ranged from 8–14 years at the time of extraction. The changes were measured on 90° left lateral cephalometric radiographs taken before extraction and approximately 12 months later. On average, there was a tendency for the overbite and overjet to increase with associated retroclination of lower and proclination of upper incisors. The range of the changes was relatively large. When the overbite showed an appreciable increase during the period of observation, pre-existing proclination of upper or lower incisors and an increased overbite or overjet were the most frequent findings. Remarkably, a previously increased overjet seemed to be a better indicator of an overbite that would increase than was the Previous overbite itself. In most cases showing a previously normal overbite or overjet, the overjet after extraction remained stable. Correlation of the overbite and overjet together against the changes in overbite proved disappointing from the prognostic standpoint except that previously incomplete overbites almost invariably increased.

A comparison of the ages at eruption of the maxillary lateral incisor to Class I and Class II occlusions

The purpose of this study was to observe overbite changes associated with interceptive orthodontic treatment at the University of Toronto. A random sample of 100 cases was studied, using pretreatment and posttreatment record casts. The overbite changes observed were compared to a sample of untreated Burlington Research Centre Controls crossmatched by age and sex. Statistically significant changes in overbite were shown to be associated with the use of cervical headgear, anterior biteplane, cervical headgear combined with anterior biteplane, Class II elastics, Class II elastics combined with cervical headgear, and cervical headgear combined with a mandibular lip plumper. In those cases which initially displayed overbite values less than the mean values for their age and sex, treatment produced a measurable increase in overbite. Cases which evidenced a deep overbite at the beginning of treatment showed a marked reduction in overbite. The findings of this study indicate that interceptive orthodontic treatment modalities available to the general practitioner can produce significant changes in overbite.

Overbite changes associated with interceptive orthodontic procedures

Overbite changes associated with interceptive orthodontic procedures

Change in overbite: A ten-year postretention study

T he general tendency for incisal overbite to “relapse” or return toward its pretreatment relationship makes this a topic of considerable interest to the orthodontist. To date, studies relating postretention changes in overbite to individual morphologic characteristics have not been conclusive. The common shortcoming in previous investigations of overbite relapse is the absence of a long-term postretention period. In studies that did have patient records with an adequate postretention period (5 years or more), there was a relatively small sample. The objective of the present investigation is to correlate incisal overbite to other craniofacial characteristics through serial evaluation of lateral cephalometric roentgenographs of seventy orthodontic,ally treated persons who have been free of retention appliances for at least 10 years.

Overbite changes in the Begg and edgewise techniques

A radiographic cephalometric appraisal was made of certain tooth movements occurring in the treatment of deep-overbite cases utilizing the Begg and edgwise techniques. Emphasis was placed upon those tooth movements which appear to affect overbite correction. The four teeth selected for this investigation were the maxillary central incisor, the maxillary first molar, the mandibular central incisor, and the mandibular first molar. Standard planes of reference were constructed from which measurements of angular and linear tooth changes were made. In addition, superimposition was made upon the anterior cranial fossa to observe changes due to general facial growth, intramaxillary and intramandibular growth, and orthodontic treatment.