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Comparison of the effects of monoblock and twin-block appliances on the skeletal and dentoalveolar structures.

Functional appliances, which are used in the early treatment period of skeletal Class II malocclusions, induce the forward displacement of the mandible by altering the postural activity of the muscles and causing some changes in both skeletal and dentoalveolar structures. The purpose of this investigation was to evaluate the differences between monoblock and twin-block appliances. Two treatment groups composed of 26 growing patients with skeletal and dental Class II, Division 1, malocclusions, were compared to an untreated control group of 13 patients with the same morphologic characteristics and growth rate. These groups were matched according to their age, sex, and vertical and sagittal skeletal cephalometric and dental characteristics. Monoblock was worn by the subjects for 16 hours/day, whereas twin-block was worn 24 hours/day, even while eating. Patients of the control group were followed without any intervention. Treatment effects were identified with a conventional cephalometric analysis. The findings of this study revealed that by using these different functional appliances, the stimulation of the growth of the lower jaw and the correction of Angle Class II relationship were achieved. In the twin-block group, the mandibular plane angle and gonial angle increased, although a decrease in the degree of overbite occurred. In the monoblock group, upper incisors demonstrated a greater degree of retrusion. However, within the twin-block group, the lower incisors showed a greater degree of proclination.

Case-Control Studies↗

Biomechanical considerations in distraction of the osteotomized dentomaxillary complex.

The completely osteotomized dentomaxillary complex is essentially a free body constrained only by its soft tissue attachments. Therefore the line of action and point of application of any protractive force(s) used during distraction osteogenesis must be considered relative to its center of mass. This is in contrast to the nonsurgically separated dentomaxillary complex, which is a constrained body, and therefore the application of protractive force(s) must be considered relative to its center of resistance. These two centers are not coincident. With knowledge of the location of the center of mass, predictable protraction of the dentomaxillary complex can be achieved. In this study, the center of mass of an adult maxillary specimen osteotomized to emulate a Le Fort I osteotomy was determined. Protractive force(s) through the center of mass will produce linear advancement along its line of action. Protractive movement of the dentomaxillary complex can be adjusted downward and forward or upward and forward by locating the protractive force(s) line of action superior or inferior to the center of mass. A cleft patient is described wherein the surgically separated dentomaxillary complex is protracted downward and forward with a force vector superior to its approximate center of mass. This results in a predictable increase in overbite and overjet with negligible mandibular rotation.

Adult↗

A study of 1000 malocclusions selected by the HLD (CalMod) Index.

The purpose was to study the results of applying the HLD (CalMod) Index to a very large population of patients. The materials were the study models of 1000 cases that had already been measured and approved for treatment. Each model was remeasured and studied. The average age of the patients was 14.138 years of age; 55% were females and 45% were males. Fifty-six percent were approved on the basis of a score of 26 or more, and 44% were approved as one of the exceptions in the index. Fifty-eight percent of the patients were Class I, 35% were Class II, and 7% were Class III. Surprisingly, 26% of all the approvals (19% adjusted for overlap) were for overjets greater than 9 mm. Reverse overjets occurred at the rate of 2% of approvals. Deep impinging overbites with tissue destruction comprised 12% of all approvals and crossbites of individual anterior teeth with tissue destruction 4%. Only 4 cleft palate cases were recorded, as they do not routinely enter the system through the index route. No traumatic deviations were found. The HLD (CalMod) Index has been field tested under a very heavy load. This study demonstrated that it selects a very wide range of malocclusions.

Adolescent↗

Anterior segmental maxillary osteotomy. A 24-month follow-up.

Anterior segmental maxillary osteotomies were performed in 14 patients. Both the downfracture and the Wunderer methods were used. The patients were examined regularly until 24 months after surgery. No major complications occurred. Long-term stability of the osteotomy was found to be acceptable except when used to correct deep overbites. In these cases, other methods should be considered.

Adult↗

Morphology of the mandibular fossa and the articular eminence in temporomandibular joints with anterior disk displacement.

The depth, length, and depth:length ratio of the mandibular fossa, and the angles of the posterior slope of the articular eminence were measured for 91 temporomandibular joints (TMJ) with anterior disk displacement (ADD) in 79 female patients with TMJ dysfunction. As a control, 48 joints in 24 females without TMJ dysfunction were similarly measured. One of the angeles of the posterior slope of the articular eminence was larger for joints with ADD than for the controls (P < 0.01, Student's t-test). There were no other statistically significant differences between the two groups. Among the 91 joints with ADD, there was no statistically significant difference in any variable between joints with ADD with reduction (n = 46) and those with ADD without reduction (n = 45); likewise, there was no association between the magnitude of angle of the posterior slope of the articular eminence and overjet, overbite, canine relationship, or molar relationship.

Adult↗

Two-couple orthodontic appliance systems utility arches: a two-couple intrusion arch.

The utility arch is a two-couple intrusion arch wire used for control of anterior deep overbite. It is similar to a one-couple intrusion arch in that it is commonly made with rectangular wire, attached to the teeth only at the molars and the incisors and is activated for incisor intrusion by a molar tip back bend. It differs from a one-couple intrusion arch by the insertion of the incisor segment into the incisor brackets. This results in a fixed point of application of the intrusion force anterior to the incisors and, therefore, incisor rotation by the moment of the force. In addition, insertion of the rectangular wire into the incisor brackets usually creates a third-order couple for incisor rotation. Depending on how it is used, the moment of this couple may be activated in either direction and the resulting associated equilibrium forces will either supplement or reduce the vertical equilibrium forces created by the activation bends at the molars.

Dental Stress Analysis↗

Selected aspects of the art and science of facial esthetics.

The historical aspects of facial esthetics and its role in orthodontic teachings and practice are traced to their origins in classical art. Related discussions include the failure of "divine proportions," the ascent of the Class II facies, and the influence of 19th century pseudoscience. Today, the treatment of facial form for a diverse society requires a tolerant sense of esthetic pluralism. Moreover, advances in neuroscience and psychology have extended understanding of the biological basis of variation in facial expression and judgment. The nature of oral esthetics was examined through quantitative studies of the smile line. Significant sexual dimorphism was found, ie, the gingival smile line (GSL) appears to be a female lineament and the low smile line seems to be a male lineament. Further results indicated that the GSL is associated with several facial characteristics, including anterior vertical maxillary excess, and the muscular capacity to raise the upper lip significantly higher than average on smiling. Other variables associated with GSL are statistically significant increases in overjet, interlabial gap at rest, and overbite. The gingival smile line is not necessarily objectionable esthetically and it will normally diminish with age. However, the treatment of choice for the GSL patient with an uncoached complaint is orthognathic surgery and orthodontics.

Adolescent↗

Treatment response and long-term dentofacial adaptations to maxillary expansion and protraction.

The purpose of this article is to summarize the short-term and long-term results of the authors' clinical prospective study on the treatment of Class III malocclusion using the protraction facemask. An attempt is made to answer questions pertaining to this treatment modality. Twenty patients with skeletal Class III malocclusion were treated consecutively with maxillary expansion and a protraction facemask. A positive overjet was obtained in all cases after 6 to 9 months of treatment. These changes were contributed to by a forward movement of the maxilla, backward and downward rotation of the mandible, proclination of the maxillary incisors, and retroclination of the mandibular incisors. The molar relationship was overcorrected to Class I or Class II dental arch relationship. The overbite was reduced with a significant increase in lower facial height. The treatment was found to be stable 2 years after removal of the appliances. At the end of the 4-year observation period, 15 of the 20 patients maintained a positive overjet or an end-to-end incisal relationship. Patients who reverted back to a negative overjet were found to have excess horizontal mandibular growth that was not compensated by proclination of the maxillary incisors. A review of the literature showed that maxillary expansion in conjunction with protraction produced greater forward movement of the maxilla. Maxillary protraction with a 30 degrees forward and downward force applied at the canine region produced an acceptable clinical response. The reciprocal force from maxillary protraction transmitted to the temporomandibular joint did not increase masticatory muscle pain or activity. Significant soft tissue profile change can be expected with maxillary protraction including straightening of the facial profile and better lip competence and posture. However, one should anticipate individual variations in treatment response and subsequent growth changes. Treatment with the protraction facemask is most effective in Class III patients with a retrusive maxilla and a hypodivergent growth pattern. Treatment initiated at the time of initial eruption of the upper central incisors helps to maintain the anterior occlusion after treatment.

Adaptation, Physiological↗

Craniofacial morphology, dental occlusion, tooth eruption, and dental maturity in boys of short stature with or without growth hormone deficiency.

The aim of this project was to study the craniofacial morphology, dental occlusion, dental maturation and tooth eruption in short-statured boys with growth hormone secretion ranging from low to high. The measurements from lateral and posteroanterior cephalograms, orthopantomograms and plaster models were used. Almost all linear measurements of the facial structures were significantly smaller. A disproportionate growth in the cranial base structures as well as in the jaws resulted in facial retrognathia, a proportionately smaller posterior than anterior facial height, and a steep vertical inclination of the mandible. Dental crowding was more common and the overbite was small. Dental maturity and tooth eruption were delayed 1.2 and 1.3 yr, respectively. No significant differences between the idiopathic short-statured and the growth hormone-deficient group in any of the above-mentioned variables were found. It can be concluded that although most of the cephalometric variables measured differed significantly from the average, the facial appearance of the boys is not conspicuous and is of minor clinical importance. However, the short-statured boys might be in greater need of orthodontic treatment due to the higher percentage of dental crowding.

Adolescent↗

A multidisciplinary treatment approach to a complicated maxillary dental trauma: a case report.

This case report describes the treatment of an 18-year-old male who lost two central maxillary incisors due to dental trauma. Because of a deep overbite and serious occlusal instability, the lost teeth 11 and 21 could not be replaced by a conventional fixed prosthesis. The vertical dimension of occlusion was increased using a Hawley-type appliance over a period of 1 year. When sufficient intermaxillary space was gained the alveolar ridge was augmented with a mandibular symphysis graft. Nine months later two one-stage non-submerged implants (ITI, Straumann, Waldenburg, Switzerland) were inserted. After further soft tissue adaptation to two temporary acrylic crowns, porcelain veneers were placed on the two implants and the lateral incisors.

Adolescent↗

Selection of dentofacial measurements for an orthodontic treatment priority index.

A battery of thirty dentofacial measurements was studied in an attempt to identify those measurements most closely related to a clinical assessment of the need for orthodontic treatment in the Dutch population. This was done by inspecting the mean values of these measurements computed within several treatment priority groups, a stepwise regression analysis relating treatment priority scores to these dentofacial measurements, and a quadratic discriminant function analysis between the group of children requiring orthodontic treatment and the group for which treatment was deemed unnecessary. The variables identified by inspection were 1) overjet, 2) overbite, 3) upper molar arch width, 4) the angle defined by articulare-gonion-menton, 5) lower arch length and 6) the ANB angle; the first four of these proved to be the most important when the contributions of all thirty of the variables to the TPI were assessed by means of the stepwise regression analysis. Overjet was also found to be an important predictor variable by Freer in relating Grainger's orthodontic TPI to dentofacial measurements in a group of patients with distoclusion; the ANB angle was found to be the most effective discriminator between normal and Class II American children. The results of the present study then, to this extent at least, agree with those found in other populations. It would appear that any "universal" TPI would have to involve those aspects of dentofacial morphology measured by overjet and the ANB angle. Within the context of the Dutch population the variables identified proved to be effective discriminators in the decision of "to treat or not to treat," correctly classifying 100% of the children in the sample who were judged by two experienced orthodontists as requiring treatment. While this decision rule did suggest treatment for 17% of the children judged to not require treatment, these cases were in the "doubtful" category (Table I) and might therefore warrant continued monitoring before any final decision is reached.

Child↗

Relationship of occlusion and periodontal disease: part IX-incisor inclination and periodontal status.

In this study population the following observations have been made: Periodontal destruction, gingival inflammation and mobility were not significantly related to axial inclination of the incisor teeth. Labial gingival recession of the mandibular incisor was related to linguoversion (less than 85 degrees to GoGn). No other associations between incisor inclination and labial or lingual recession were found. Age was not related to either maxillary or mandibular incisor inclination. The periodontal-incisor inclination relationships reported above for periodontal destruction and gingival inflammation were not altered by the factor of age. Study of the secondary influence of incisor inclination on the relationships of selected occlusal factors and periodontal pathosis showed: A. Severe overjet (more than 6mm) had been found to be associated with more periodontal destruction. With severe overjet maxillary incisors in linguoversion (less than 100 degrees to SN) were somewhat healthier than all others. Among the same cases of severe overjet mandibular incisors in labioversion had slightly more disease than all others. B. The absence of a significant correlation between anterior overbite or crowding reported previously was not influenced by incisor inclination. C. Facial alveolar bone thickness, observed clinically, was studied for its relation to periodontal destruction and gingival inflammation. Thick facial alveolar bone was found to be associated with increased pathosis. This finding was not consistent for the maxillary and mandibular incisor and the influence of other factors might be suspected: Incisor inclination had no effect on the bone thickness-periodontal disease findings.

Adolescent↗

The application of quantitative perioral assessment to orthodontic case analysis and treatment planning.

Maximum tonicity of the lips can be accurately measured through the use of the pommeter. 2. Patients with significant hypertonicity of the lips whose maxillary central incisors are positioned oingualy as in Class II, Div. 2 and also in certain Class I malocclusions should be treated nonextraction and as early as possible. Torguing maxillary incisors into a more normal labial axial inclination is a form of expansion which does not detrimentally affect the position and function of the perioral muscles. In this early conservative approach not only is arch length increased but also marked improvement in the overbite is accomplished. These types of treated malocclusions should be retained until after the eruption of the second permanent molars. 3. If extraction is necessary in patients with hypertonic lip muscles it should be done as far as possible from the incisor teeth, preferably the second premolars. 4. In Class I malocclusions where maximum tonicity is in the normal range is to attempt to accommodate blocked out or rotated teeth within the framework of the perioral musculature surrounding the teeth...

Adolescent↗

The mandibular plane angle in activator treatment.

The long-term results of activator treatment were investigated in 15 subjects with a small and 13 subject with a large pretreatment mandibular plane angle. The results of the investigation revealed the following: 1. Activator treatment resulted in a general improvement in the sagittal and vertical incisor relationship in both large and small angle cases. 2. Overjet relapse was more frequent and overbite relapse less frequent in large angle cases than in small angle cases. 3. During the period before treatment follow-up examination the frequency of patients with open bite increased in the large angle group and decreased in the small angle group. 4. The mandibular intercanine arch width was smaller and the frequency of crowding in the mandibular incisor segment was higher in the large angle group than in the small angle group. 5. A large pretreatment mandibular plane angle, per se, was not a primary factor in treatment failure. However, an unfavourable mandibular growth in combination with an atypical tongue function seemed to be the main reason for the relapse found in the large angle subjects.

Activator Appliances↗

Soft tissue changes associated with mandibular subapical osteotomy.

Sophisticated treatment planning for those individuals with severe dental and facial disproportions requires accurate prediction of posttreatment results. Preand posttreatment cephalometric X-rays for a group of twelve patients treated by a combined orthodontic-oral surgical approach were evaluated. The surgery was of either the standard mandibular subapical osteotomy or Kole type of procedure. Surgical repositioning of the anterior mandibular alveolus resulted in various changes in hard tissue and soft tissue profile. In summary, these changes were: 1. Decreased lower facial height. 2. More relaxed lip posture as revealed by an increased superior vermilion lip length and decreased inferior vermilion lip length. 3. Stomion moved inferior and posterior relative to the lower facial plane. 4. Superior labial sulcus became less concave. 5. Inferior labial sulcus became more concave. 6. Superior vermilion and inferior vermilion moved posterior relative to the lower facial plane. 7. Chin radius and lip-chin-throat angle decreased. 8. Overbite and overjet increased while Wits analysis decreased. 9. Facial contour angle was unchanged. Changes were similar for both standard subapical and Kole groups with the main difference being a greater reduction in facial height with the Kole group.

Adolescent↗

A comparative cephalometric study of Class II, Division 1 nonextraction and extraction cases.

1. Cephalometric tracings of thirty Class II, Division 1 cases without extraction and twenty-five Class II, Division 1 cases with extraction were evaluated and statistically compared by means of the overbite depth indicator (ODI) and the anteroposterior dysplasia indicator (APDI). 2. The mean ODI in the nonextraction group, in particular, was significantly higher than that of the extraction group. 3. Three clinical examples were presented to demonstrate the values of ODI and APDI as adjuncts to cephalometric differential diagnosis. 4. With respect to the vertical component it may be concluded that the lower the ODI value from the normal mean a case presents, the greater the incidence of an extraction procedure as a compromise for the poor skeletal pattern. 5. With respect to the horizontal component the initial APDI reading indicates the severity of skeletal discrepancy. When the posttreatment APDI reading falls below the normal mean, a relapse is probable: the lower the figure a case possesses, the greater the chance of relapse. In such incidences an extraction procedure must be provided to ensure the stability of occlusion.

Adolescent↗

Anomalies of occlusion predisposing to occlusal interference in children.

The associations between different types of occlusal interference and of occlusal anomalies were studied in children 7, 11 and 15 years of age. Incisor and buccal crossbite and post-normal occlusions were positively related to large antero-posterior distance or lateral deviation between the retruded and intercuspal mandibular positions, and to nonworking side interference. There was a positive correlation between frontal open bite and nonworking side interference, while large overbite was negatively correlated. The correlations found were numerically small, indicating that other factors apart from those studies must be significantly involved in such occlusal interferences.

Adolescent↗

Maxillary incisor intrusion and facial growth.

A palate and first molar anchorage appliance is used to intrude upper incisors, and the effects on dental and skeletal variables are examined in 25 growing females and 25 matched controls. On average, the mandible was unaffected for the entire treated sample, but those with the largest reduction in overbite showed more increase in mandibular length than expected.

Cephalometry↗