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Changes in the dentition secondary to palatal crib therapy in digit-suckers: a preliminary study.

This study investigated the effect of the palatal crib appliance used in the correction of open bite malocclusions secondary to fingersucking. Twelve experimental and 12 control subjects were studied for an average of 3.9 months. The sample consisted of patients who were both growing and not growing. Study models taken before and after the study period were analyzed for changes in the following dimensions: overbite, overjet, arch perimeter, arch length, and incisor angulation. Data were analyzed with student t-tests to determine statistical significance. Partial or complete closure of the open bite was achieved averaging 3.7 mm +/- 1.9 mm during the observation period in the experimental group treated with palatal crib therapy. In contrast, the control group displayed a mean bite opening of 0.4 mm +/- 0.8. These values were statistically significant at the P < 0.001 level. Open bite decreased as incisor angulation (P < 0.02), arch length (P < 0.05), and arch perimeter (P < 0.01) decreased. Overjet changes were minimal and statistically insignificant.

Adolescent↗

Effects of nonnutritive sucking habits on occlusal characteristics in the mixed dentition.

PURPOSE: Little is known about the extent to which nonnutritive sucking habits contribute to malocclusion in the mixed dentition. The purpose of this study was to report on the relationship between certain occlusal traits in the mixed dentition and longitudinal sucking behaviors. METHODS: Dental examinations were conducted on 630 children in the mixed dentition who participated in a large, ongoing longitudinal study. Five hundred eighty consented to impressions, and 524 adequate study models were obtained. Of these, 444 also had adequate longitudinal nonnutritive sucking data obtained via mailed questionnaires to parents at 3- to 6-month intervals from birth to 8 years. Sucking behaviors were grouped by predominant type and duration. Study models were hand articulated using wax bites to evaluate the occlusion for the presence of open bite, crossbite, molar relationship, and excessive overjet. Bivariate statistical analyses related presence of these malocclusions to sucking duration and type. RESULTS: Fifty-five percent of the children had malocclusions (anterior open bite, posterior crossbite, bilateral Class II molar relationship, or overjet >4 mm). Class II molar relationship was most common (30%). Overall, anterior open bite and posterior crossbite was associated with habits of 36 months or more. Sustained pacifier habits, including those of 24 to 47 months, were associated with anterior open bite and Class II molar relationships, while digit habits were associated with anterior open bite when sustained for 60 months or longer. CONCLUSIONS: Malocclusions are quite prevalent in the mixed dentition, and anterior open bite and posterior crossbite may be preventable by modifying nonnutritive sucking behaviors.

Chi-Square Distribution↗

Occlusal characteristics during different emergence stages of the permanent dentition in Tanzanian Bantu and finnish children.

Occlusal characteristics and anomalies were studied among 869 (428 boys, 441 girls) Tanzanian Bantu children aged 3.5-16 years and 706 (319 boys, 387 girls) Finnish children aged 5-11 years during different emergence stages of the permanent dentition. Various occlusal variables were registered according to described criteria. Multiple linear regression, ANOVA, t-test, Chi-square and logistic regression models were used to test for various statistically significant differences between different subgroups. Significant differences between Tanzanians and Finns were found for malocclusion, neutral and distal molar occlusion, mean values for overjet and overbite, overjet greater than 5 mm, deep bite and anterior open bite (all P < 0.0001). The most prevalent anomalies among Tanzanians were anterior open bite (7-19 per cent), increased overjet (3-19 per cent) and distal molar occlusion (3-16 per cent). For the Finns, distal molar occlusion (18-38 per cent) was the most prevalent anomaly, followed by deep bite (4-22 per cent) and increased overjet (4-40 per cent). An anterior crossbite was rare and equally distributed among the two ethnic groups. Girls had a larger mean value for overbite (P = 0.003) and more often a deep bite (P < 0.01) than boys. Mandibular incisor crowding among children with neutral occlusion (Class I malocclusion) occurred significantly more often among Finnish than Tanzanian children. In conclusion, various developmental changes in occlusion were observed leading to variation in occlusal characteristics and anomalies according to the emergence stages of the permanent dentition. Most of the classic malocclusions occur among Tanzanian children, but the prevalence differs from that in other parts of the world.

Adolescent↗

[Posterior disk displacement of the temporomandibular joint. Apropos 2 cases].

Posterior displacement of the temporo-mandibular joint disk is exceptional. The most typical clinical sign is sudden onset unilateral molar open bite. This lateral open bite is accompanied by a sensation of an intra-articular foreign body and more rarely by painful episodes. The joint sounds are not characteristic. Mouth opening is slightly limited. There is no consensus concerning treatment. Conservative treatment can be prescribed in cases with functional impairment. First line invasive techniques should be avoided.

Adult↗

Adaptation of guinea-pig superficial masseter muscle to an increase in occlusal vertical dimension.

To study the effect of increased occlusal vertical dimension on the fibre phenotypes of the superficial masseter muscle, the composition of myosin heavy-chains (MHC), myosin light-chains (MLC) and tropomyosin was investigated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and two-dimensional gel electrophoresis in conjunction with densitometric analysis in normal (control) and bite-opened (5.7 mm increase in the vertical dimension for 1 week) guinea-pigs. The superficial masseter contained two fast-type MHC isoforms, II-1 and II-2, in both the bite-opened and control groups; their relative content (mean+/-SD, n = 7) was 47.8+/-2.9% and 52.2+/-2.9%, in the bite-opened and 44.4+/-3.0% and 55.6+3.0% in control preparations, indicating no significant (p>0.05) changes in MHC composition in association with the bite opening. On the other hand, significant differences in MLC and tropomyosin composition were found between the two preparations. Although the MLC consisted of three components, LC1f, LC2f and LC3f, in both preparations, their relative content (mean+/-SD, n = 7) was 37.1+/-2.4%, 49.6+/-1.6% and 13.2+/-3.2%, respectively, in the bite-opened and 28.1+/-3.1%, 50.9+/-1.6% and 21.0+/-3.5% in the control preparations, indicating that the bite opening induced a significant (p < 0.0001) increase in the relative content of LC1f at the expense of that of LC3f. Although the tropomyosin consisted of two components, TM-alpha and TM-beta, in both preparations, their relative content (mean+/-SD, n = 7) was 91.8%+/-1.9% and 8.2+/-1.9%, respectively, in the bite-opened and 95.9+/-0.7% and 4.1+/-0.7% in the control preparations, showing a significant (p < 0.001) increase in the relative content of TM-beta in relation to the bite opening. These results indicate that in guinea-pigs an increase in occlusal vertical dimension for 1 week changes the composition of MLC and tropomyosin, with no significant change in MHC, in the masseter muscle. These changes might be required to meet altered functional demands.

Adaptation, Physiological↗

Electromyographic and ultrasonographic observations of masseter and anterior temporalis muscles in children.

Muscle thickness and activity of masseter and anterior temporalis muscles in children with Class I molar occlusion having normal anterior relation, anterior deep-bite and anterior open-bite were measured using ultrasonographic and electromyographic techniques. The results demonstrated an increased muscle thickness in the deep-bite followed by open-bite subjects. Muscle activity was high in the same groups. A significant correlation between thickness and activity was noted only in the anterior temporalis muscle of subjects with normal anterior relation. Activity index indicated that masseter contributed to the higher activity in the clenching effort.

Child↗

Insufficient endogenous control of tumor necrosis factor-alpha contributes to temporomandibular joint pain and tissue destruction in rheumatoid arthritis.

OBJECTIVE: To investigate whether pain and tissue destruction in the temporomandibular joint (TMJ) of patients with rheumatoid arthritis (RA) are influenced by plasma levels of the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) or the soluble receptor TNFsRII. METHODS: Fifty-one patients with RA were included. TMJ resting pain intensity, pain intensity upon mandibular movement, tenderness to palpation, pressure-pain threshold, and presence of anterior open bite were assessed. Venous blood was obtained for analysis of TNF-alpha, TNFsRII, and inflammatory markers. RESULTS: A total of 29 patients had TMJ pain and 22 patients had anterior open bite. In the group of patients with TMJ pain, 12 had anterior open bite and 17 did not. In the patients without TMJ pain 10 patients had anterior open bite and 12 did not. Patients with or without anterior open bite did not differ regarding any investigated variable. Plasma TNF-alpha and TNFsRII were positively correlated in the total patient sample. TNFsRII was negatively correlated with degree of anterior open bite in patients with TMJ pain but positively correlated with TMJ pressure-pain threshold in patients with elevated plasma TNF-alpha. CONCLUSION: Our results indicate that insufficient systemic endogenous control of TNF-alpha seems to contribute to TMJ pain and tissue destruction in RA.

Arthralgia↗

Skeletal and dental effects during observation and treatment with a magnetic device.

The aim of this study was to evaluate the effects of a magnetic appliance, MAD IV, on the treatment of anterior open bites in growing patients. The study material included the lateral cephalograms and hand-wrist radiographs of 16 patients who had an anterior open bite malocclusion. The radiographs were taken at the beginning (T1) and at the end of observation period (T2) and at the end of MAD IV application (T3). At the beginning of the study, the mean age of the subjects was 11 years two months. To define the direction of facial growth, the patients were first observed for nine months without any orthodontic or orthopedic approach. At the end of the observation period, patients who had shown a vertical growth direction, resulting in an increase in open bite, were given an MAD IV appliance and were instructed to wear the appliance 18 hours a day for 7.5 months. Thirty-two different parameters were evaluated from the lateral cephalograms. Paired t-tests were used for statistical evaluation of differences that occurred during the periods and between the periods. During the observation period, the patients continued their mandibular posterior rotation resulting in an increase in lower facial height (P < .001) and an open bite (P < .01). During the treatment period, the patients showed an anterior mandibular rotation with statistically important decreases in lower facial height and open bite (P < .001). In the treatment of anterior open bite with the MAD IV appliance, skeletal changes played a role along with dental and dentoalveolar effects.

Adolescent↗

Altered jaw posture and occlusal disruption patterns following mandibular advancement therapy for sleep apnea: a preliminary study of cephalometric predictors.

PURPOSE: Reports of irreversible alteration in jaw posture and destructive occlusal contact relationships in individuals using mandibular advancement devices for obstructive sleep apnea are beginning to appear. This study sought cephalometric means of identifying such individuals before commencing therapy. MATERIALS AND METHODS: Cephalograms of 34 obstructive sleep apnea sufferers who had worn mandibular advancement devices for 2 years were compared retrospectively with baseline films taken at commencement of therapy and analyzed for signs of morphologic changes in jaw position and occlusal relationship. In affected patients, two distinct morphologic species of mandibular reposturing became evident: (1) bilateral posterior open bite with destructive incisal attrition; and (2) less destructive intermediate open bite over the premolar and first molar regions. From the observed morphology patterns, gonial angle and maxillary-mandibular plane angle were analyzed as possible vertical cephalometric risk predictors, with newly defined pterygoid advancement proportion (PtAP) as a horizontal predictor. RESULTS: Three patients displayed the posterior open bite pattern and had gonial angles < or = 119 degrees and maxillary-mandibular plane angles < or = 16 degrees, with PtAP values > or = 0.48. Prediction intervals for the five intermediate open bite cases were 118 degrees < or = gonial angle < or = 128 degrees, and 23 degrees < or = maxillary-mandibular plane angle < or = 32 degrees. PtAP values were > or = 0.52. CONCLUSION: Cephalometric analysis can help practitioners identify which apnea patients might be likely to develop irreversible mandibular postural changes from wearing a jaw-repositioning device.

Cephalometry↗

Effects of cervical headgear on overbite against the background of existing growth patterns. A retrospective analysis of study casts.

OBJECTIVE: To test the questions "Does cervical headgear treatment necessarily lead to a reduction of overbite?" and "Are there differences in treatment results due to different growth patterns or the initial overbite?" MATERIALS AND METHODS: Initial and intermediary casts of 247 patients who had been treated exclusively with headgear were analyzed for changes in the occlusal relationship of the first molars and overbite. Orthodontic treatment consisted of the application of cervical headgear with nonangulated external arms applied at a force of 3.5-4.0 N. Only patients showing dental changes of occlusal relationship > or = 4 mm during at least a 6-month treatment duration were selected. Growth patterns were identified by the y-axis values measured on lateral cephalograms obtained at study entry. Six groups were formed on the basis of these growth patterns. RESULTS: Headgear treatment induced bite deepening in patients with vertical growth patterns and bite opening in patients with horizontal growth patterns. Further subdivision based on initial overbite revealed bite deepening in patients with small initial overbite and bite opening in patients with large initial overbite. These differences were statistically significant (P < .05). Only minor changes were observed in patients with an initial overbite of 3-4 mm. CONCLUSIONS: Overbite reductions were not dependent on the growth pattern. Orthodontists should expect bite opening in deep-bite situations and bite deepening in open-bite situations. However, initial overbite situations of 3-4 mm should not be expected to change in a significant way.

Cephalometry↗

Increase in vertical dimension alters mechanical properties and isometric ATPase activity in guinea pig masseter.

To study the changes in mechanical and metabolic properties associated with an increase in the vertical dimension of the face, isometric tension, isometric ATPase activity, unloaded shortening velocity (Vmax), and the tension transients in response to step stretches in length were measured at constant levels of various Ca2+ activations in glycerinated masseter muscles (75 to 150 microns in diameter and about 3 mm long) from normal and bite opened (6 mm increase in the vertical dimension, period of 1 week) guinea pigs. The isometric tension increased sigmoidally with an increase in Ca2+ concentration in both preparations. However, the bite opening shifted the pCa-relative tension relationship in the direction of increasing Ca2+ required for activation, and the pCa at Km (Ca2+ concentration required to develop half maximum tension) was 6.40 +/- 0.08 in control and 6.27 +/- 0.05 in the bite opened preparations. The maximum isometric tension at the saturating Ca2+ concentration was greater in the bite opened preparation. The ATPase activity changed almost in parallel with the tension (i.e., Ca2+ concentration) in both preparations. However, the tension cost (ATPase activity/tension) was significantly (p < 0.05) lower in the bite opened preparation, compared with the control. The Vmax at the saturating Ca2+ concentration was lower in the bite opened preparations. The tension transients in response to step stretch in length were characterized by four distinct phases; the first phase of an immediate tension increase coincident with the stretch, the second phase of a rapid quasi-exponential tension reduction, the third phase of a minute tension increase and the fourth phase of a slow tension reduction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗

The effect of sagittal orientation of the distractor on the biomechanics of mandibular lengthening.

PURPOSE: It has been previously demonstrated that distractors placed parallel to the mandible in the transverse plane, without regard to the vector of distraction create lateral displacement tendencies at the appliance-bone interface, leading to potential clinical problems and complications. The purpose of this study was to evaluate the biomechanical effects of linear distractor orientation in the sagittal plane relative to the anatomic axis of the mandible (mandibular plane) and the maxillary occlusal plane. MATERIALS AND METHODS: A 2-dimensional model of the human mandible was generated for computer simulation of osteodistraction. Positional changes of the distal mandibular segment were then analyzed during 10 mm of incremental lengthening based on distractor orientation relative to the maxillary occlusal plane. RESULTS: Distractors placed parallel to the inferior border of the mandible without regard to the maxillary occlusal plane created a vertical translation of the distal bone segment resulting in an anterior open bite. The magnitude of the anterior open bite was proportional to the angle between the vector of distraction and the maxillary occlusal plane, and to the amount of distraction. Placement of the distractors parallel to the maxillary occlusal plane eliminated the tendency for an anterior open bite. CONCLUSIONS: The orientation of the distractors relative to the maxillary occlusal plane is one of the important biomechanical parameters that must be included in preoperative planning for mandibular osteodistraction.

Biomechanical Phenomena↗

[Effect of the early intervention of oral habits on the development of dental occlusion].

BACKGROUND: Sucking habits are related to malocclusion. AIM: To evaluate the effect of a counseling interview about inhibiting this oral habit and, its influence on dental occlusion and labial-lingual posture. METHOD: 40 children (mean age = three years), with a sucking habit and anterior open bite, received counseling aiming for the interruption of this habit. Measurements of the open bite were made, as well as a myofunctional evaluation, prior to counseling and, three and six months after it. RESULTS: 26 children stopped with the habit of sucking, with 25 children presenting a reduction of the open bite. No change was observed in labial-lingual posture. CONCLUSION: The counseling interview favored the interruption of the oral habit and the correction of the open bite.

Bottle Feeding↗

Overbite and overjet characteristics of refined diagnostic groups of temporomandibular disorder patients.

Overbite and overjet were studied as continuous variables to examine for any relationship to diagnostic groups of temporomandibular disorders (TMD) compared with symptom-free controls. This avoided the bias of arbitrary definitions of normal and abnormal for these occlusal variables and also avoided the masking effect of studying symptoms rather than diagnostic entities. Incisal overbite in primary osteoarthrosis (OA) was shifted toward the minimal and open bite ranges as compared with the controls (p less than 0.02). Open bite occurred in only the two OA classes studied and in a few cases with myalgia only but was absent in the symptom-free controls. Overbite in myalgia was slightly skewed to the lower range. Deep bite was not more common in the myalgia, disk displacement (with or without reduction), or the OA groups. Increased overjet characterized OA groups, especially when there was a history of derangement (p less than 0.004), but did not characterize the other diagnostic groups. Except for open bite, overbite and overjet characteristics as isolated variables did not distinguish TMD patient groups. It is hypothesized that open bite in OA can be the result of joint changes rather than a predisposing occlusal cause.

Adult↗

Variations of the gonial angle in vertical surgical reduction of the maxillary-mandibular complex.

From an esthetic point of view, the mandibular or gonial angle plays an important role in ensuring a harmonious facial profile. The purpose of this study was to analyze the values of the mandibular angle in relation to variations of the vertical and sagittal positions of the jaw. The study was carried out on a sample of 42 patients who underwent surgery for maxillary-mandibular repositioning, advancing or raising the jaw, after a Le Fort I osteotomy and bilateral sagittal osteotomy of the jaw according to the technique described by Obwegeser-Dal Pont. In all patients, the maxillary bone was raised with a discrepancy of at least 3 mm between the anterior and posterior portions (favoring the latter) as a result of (clockwise) rotation of the bispinal plane. The data, obtained by means of cephalometric analysis according to the method of Ricketts, showed how changes in the gonial angle differed between patients who require correction of an open-bite and those who do not. In particular, in patients without an open-bite, advancement of the maxilla limited the opening of the angle. Similarly, in patients with an open-bite, the tendency to form an open gonial angle can usually be corrected by the association of advancement of the maxilla whenever possible.

Adolescent↗

Growth patterns in subjects with long and short faces.

The purpose of this study was to assess skeletal factors associated with the development of vertical facial disproportions. Angular measurements based on longitudinal lateral cephalometric radiographs of 16 male and 16 female subjects, from the ages of 4 through 18 years, were used. Subjects were selected on the basis of lower face height (ANS-Me) as a percentage of morphologic face height (N-Me). A single x-ray photograph at age 15 for the boys and 13.5 for the girls was used to classify each subject's occlusion as either open-bite or deep-bite. Sella-nasion/palatal plane, sella-nasion/mandibular plane, sella-nasion/anatomic occlusal plane, palatal plane/mandibular plane, and cranial base angle were analyzed statistically and graphically. It was found that (1) with the exception of sella-nasion/palatal plane and cranial base angles, all angular measurements demonstrated a progressive reduction throughout development in both open bites and deep bites; (2) the palatomandibular angle discriminated between open bites and deep bites throughout the developmental phase; (3) within each sex, typologic differences were evident in all angular measurements, with the exception of cranial base and occlusal plane; and (4) the cranial base angle demonstrated clear sexual dimorphism, and its magnitude was not associated with vertical dysplasia. The progressive reduction of angles in skeletal open bite reduced or maintained the magnitude of the imbalances, while the reduction of angles accentuated the skeletal deep bite with age. The inclination of the palatal plane and its constancy suggested that downward and backward rotation of the mandible in open bite subjects is precommitted in response to dentoalveolar compensatory changes with the center of rotation at the molars. The magnitude of the mandibular plane angle is not adequate for assessment of diagnostic or prognostic predictive value in determining the pattern of growth.

Adolescent↗

Craniofacial structure related to inheritance pattern in amelogenesis imperfecta.

The aim of this study was to investigate the craniofacial structure in 66 children and adolescents, 34 girls and 32 boys, with known clinical manifestations and inheritance patterns for amelogenesis imperfecta (AI), and to compare the results with those obtained in a control group of age and sex matched persons with normal occlusion. The ages ranged from 6.8 to 21.2 years. Clinically, AI was divided into cases characterized by either hypoplasia or hypomineralization of the enamel. In a further subgrouping, eight clinical variants were diagnosed. Measurements of 12 angular and 15 linear, parameters on lateral cephalometric radiographs were included in comparisons between the AI and the control group. Compared with the control group, the AI group displayed statistically significant differences indicating a skeletal open bite. In the analysis of inheritance patterns and clinical manifestations, a skeletal open bite was associated with autosomal dominant (AD) and X-linked inheritance, and in the AD group with hypomineralization. When all cases except those with X-linked inheritance were pooled, deviations indicating a skeletal open bite were found in the subgroups "rough hypoplastic AI" and "hypomineralization AI." Since a skeletal open bite was found both with X-linked inheritance and in some of the subgroups connected with autosomal inheritance, the hypothesis of a pleiotropic gene effect as the cause of the simultaneous occurrence can be ruled out. The influence of modifying genes or environmental factors is suggested.

Adolescent↗

Anterior tooth relations in Kenyan Africans.

Dental plaster casts of 235 Maasai, 116 Kikuyu and 61 Kalenjin children aged 3-16 yr were studied to determine the incidence and magnitude of diastemas, overbite, overjet and anterior open bite. The highest prevalence of diastema was amongst the Maasai (61.3%), of overbite (84%) and overjet (99%) amongst the Kikuyu, and of anterior open bite amongst Kalenjin (24%), with values greater than 0.4 mm up to 11.5 mm. Comparison of the mean values showed that diastema (1.77 mm) and overjet (4.4 mm) were greatest in Maasai, overbite (3.53 mm) in Kalenjin, and anterior open bite (3.50 mm) in Kikuyu. In the total sample, the prevalence and mean of diastema were 49%, 1.68 mm; of overbite 77.4%, 2.96 mm; of overjet 88.6%, 3.83 mm; and of anterior open bite 16.5%, 2.69 mm (with values between 0.4-11.5 mm), while 5.5% had an edge-to-edge bite (-0.5-0.5 mm). The prevalence of diastema decreased whilst its magnitude increased with age. The mean values of overbite and overjet increased, while those for anterior open bite decreased with age. The mean values of diastema, overbite and overjet were greater amongst the females, but the difference was significant only for overjet. The high prevalence and greater values of measurements of anterior tooth relations may be related to variable growth of the bimaxillary dentoalveolar complex and soft tissue influences. This may be important in orthodontic treatment planning, dental prostheses and other clinical dental treatments in Kenyan populations.

Adolescent↗