ABSTRACT
Long fiber-reinforced composites (FRC) have been shown to have enhanced mechanical properties that allow their use in orthodontic appliances as bars that join teeth to form either anchorage or active units. This study was designed to determine if the bonding of an orthodontic attachment has sufficient strength to withstand loading during clinical use. The experimental model consisted of a hydroxyapatite stone that simulated enamel, FRC bars, and a bonded metal hook. Three specimen types were compared: (1) a metal hook-pad (the control), (2) a woven FRC with a hook-pad, and (3) a unidirectional FRC with a hook-pad. Loads were applied both parallel and at 90 degrees to the tooth surface. Under no condition was the FRC pad combination weaker than the control pad. Under some loading conditions, the loads before failure were as much as 3 times greater than those for the control. The lowest strength was found with loads at 90 degrees to the tooth surface for all 3 types. Failure normally occurred in the FRC and rarely at the bracket or tooth interface. The excellent bonding of the orthodontic attachment to the FRC and the high strengths of the FRC attachment combination demonstrate the ability to form connecting bars between teeth for either anchorage or active segmental movements. These bars offer advantages in simplicity in treatment by reducing the need for some bands, attachments, or wires.
Subject(s)
Composite Resins/chemistry , Dental Bonding , Orthodontic Appliance Design , Dental Stress Analysis , Durapatite , Humans , Materials TestingABSTRACT
Critical anchorage during orthodontic treatment in the mandible needs both time and effort and patient compliance. In 8 patients, 12 bicortical titanium screws (BIS) were used as anchorage units for orthodontic molar protraction. The criteria for patient selection were: critical anchorage in the lower jaw (i.e. retraction of anterior teeth undesirable) and molar extraction sites. After insertion of the screws in local anesthesia, orthodontic forces were applied immediately. One screw worked loose and had to be removed before the end of treatment. Problems encountered included impingement of the screw head and slight inflammatory reactions of the surrounding mobile mucosa, which necessitated premature removal of two screws. After healing, a new insertion site was chosen. Further treatment was uneventful. Anchorage for orthodontic forces as described offers several advantages. The total treatment time is reduced as the screws can be loaded immediately. The line of action of the orthodontic force coincides with the level of the center of resistance of the molar resulting in a favorable translatory tooth movement. Treatment does not depend on patient cooperation.
Subject(s)
Dental Implants , Orthodontic Appliance Design , Tooth Movement Techniques/instrumentation , Adolescent , Adult , Dental Stress Analysis , Female , Humans , Male , Mandible/surgery , Middle Aged , TitaniumABSTRACT
This study was carried out to investigate the validity of the overbite depth indicator (ODI) and the anteroposterior dysplasia indicator (APDI), based on the cephalometric analysis of 122 Caucasians selected at random for assessment of vertical and sagittal relationships. Considering the occlusion, the sample was divided into three classifications in the sagittal component: 36 cases of neutrocclusion, 54 cases of distocclusion, and 34 cases of mesiocclusion. The sample was also categorized according to the overbite relationship: 54 cases of normal overbite, 34 cases of open bite, and 34 cases of deep overbite. In the sagittal component analysis, the APDI measurement resulted in significant differences between the neutrocclusion, distocclusion, and mesiocclusion groups. In the vertical component analysis, the ODI significantly distinguished between the normal and deep overbite groups, and the open bite and deep overbite groups, but not between the normal overbite and the open bite groups. A receiver operating characteristic (ROC) analysis showed that the APDI matched the anteroposterior molar relationship in 88 per cent, and the ODI matched the amount of incisor overbite in 81 per cent.
Subject(s)
Cephalometry , Diagnosis, Oral/methods , Malocclusion/pathology , Adolescent , Adult , Analysis of Variance , Child , Female , Humans , Male , Malocclusion/diagnostic imaging , ROC Curve , Radiography , Reproducibility of Results , Sampling Studies , Statistics, Nonparametric , Vertical DimensionABSTRACT
This study evaluated the ability of some cephalometric measurements to differentiate between horizontal and vertical malocclusions and normal occlusion. Based upon the Angle classification and the vertical incisor overbite, 122 randomly selected subjects were assigned to 3 horizontal and 3 vertical groups: neutrocclusion, distocclusion, mesiocclusion as well as open bite, normal overbite, and deep bite. Evaluation of the lateral cephalograms was based on Denture Frame Analysis and cephalometric standard measurements (SNA, SNB, ANB, Wits appraisal, Björk polygon, overbite depth indicator, incisor inclination, incisor protrusion, facial height ratio). The statistical evaluation assessed the ability of the measurements to show significant differences between the individual horizontal and vertical groups. Using Denture Frame Analysis, all vertical groups could be differentiated by the occlusomandibular angle (OP-MP) and all horizontal groups by the angle between the A-B plane and the mandibular plane as well as by the inclination of the upper incisors to the A-B plane with statistical significance (p < 0.05). Among the standard measurements, the Wits appraisal was the only one to show differences between all horizontal groups with statistical significance. None of the standard measurements could fully differentiate the vertical groups. The above measurements from the Denture Frame Analysis distinguished the types of malocclusion in anteroposterior and vertical direction including significant distinction between the neutrocclusion group and the malocclusion groups. Therefore a cephalometric classification was feasible in terms of hyper- and hypodivergence as well as of a mesial or distal dentofacial relationship.
Subject(s)
Cephalometry/methods , Malocclusion/diagnosis , Vertical Dimension , Adolescent , Adult , Analysis of Variance , Cephalometry/statistics & numerical data , Child , Child, Preschool , Diagnosis, Differential , Europe , Female , Humans , Male , Observer Variation , Random AllocationABSTRACT
The purpose of this study was to evaluate the Denture Frame Analysis. This adjunctive cephalometric analysis of the lateral headfilm was introduced in Japan, but no data exist for the Caucasian population at present. One-hundred-and-six Caucasians were randomly selected and assigned to one of four groups, according to their malocclusion: Angle Classes I, II, and III, and anterior open bite. Statistical testing showed significant differences among the four groups for most of the measurements investigated. The Denture Frame Analysis distinguished the different types of malocclusion, and evaluated skeletal and dental relationships. The occlusal plane aids in the determination of the objectives and limits of orthodontic therapy.
Subject(s)
Cephalometry/methods , Malocclusion/diagnosis , Adolescent , Adult , Child , Child, Preschool , Dental Arch/pathology , Evaluation Studies as Topic , Female , Humans , Incisor/pathology , Male , Malocclusion/therapy , Malocclusion, Angle Class I/diagnosis , Malocclusion, Angle Class II/diagnosis , Malocclusion, Angle Class III/diagnosis , Mandible/pathology , Maxilla/pathology , Molar/pathology , Orthodontics, Corrective , Palate/pathology , Patient Care Planning , Vertical Dimension , White PeopleABSTRACT
Centric relation records of 19 dental students were obtained with leaf gauges and by mandibular manipulation. The condyle/fossa relationships were subsequently evaluated with enhanced sagittal cephalometry. Both clinical methods of obtaining centric relation revealed considerable variation of the condyle location within the glenoid fossa. Only 10% of the patients showed a condyle position "upward and forward" in the fossa with the leaf gauge method. In the mandibular manipulation technique of obtaining centric relation, 10% of the patients showed an "upward and rearward" position of the condyle.
Subject(s)
Centric Relation , Jaw Relation Record/methods , Mandibular Condyle/anatomy & histology , Adult , Cephalometry , Female , Humans , Male , Mandible , Manipulation, Orthopedic , Temporomandibular Joint/anatomy & histologyABSTRACT
Bilateral bite force was measured in a sample of 457 subjects (231 males and 226 females) from 6 years through 20 years. The mean maximum bite force was found to increase from 78 Newtons at 6 to 8 years to 176 Newtons at 18 to 20 years. While earlier studies have shown adult males have a greater mean bite force than females, this difference is not evident during growth and development. Gender-related bite force difference likely develops during the postpubertal period in association with greater muscle mass development in males.
Subject(s)
Bite Force , Growth , Adolescent , Adult , Aging , Bicuspid/physiology , Child , Facial Muscles/growth & development , Female , Humans , Linear Models , Male , Molar/physiology , Muscle Development , Puberty , Sex Factors , Stress, Mechanical , Tooth, Deciduous/physiology , TransducersABSTRACT
A new device for measuring and recording bilateral bite force in the molar/premolar region has been developed. Because this new device is elastic and conforms to the occlusal surfaces of the teeth, and because the sensing element is relatively comfortable, it is believed that experimental subjects are less reluctant to register true maximal forces than in earlier studies. Potential correlations of maximum bite force to gender, age, weight, body type, stature, previous history of orthodontic treatment, presence of TMJ symptoms (jaw motion limitation, clicking with pain, or joint pain), or missing teeth were studied in a sample of 142 dental students. The mean maximum bite force of the sample was found to be 738 N, with a standard deviation of 209 N. The mean maximum bite force as related to gender was found to be statistically significant, while the correlation coefficients for age, weight, stature, and body type were found to be low. Even so, all data scatterplots exhibited relatively positive relationships. Correlations of maximum bite force to an earlier history of orthodontic treatment or to the absence of teeth were not found. Subjects reporting TMJ symptoms did not exhibit a significantly different maximum bite force than subjects without symptoms.
Subject(s)
Bite Force , Adult , Age Factors , Bicuspid/physiology , Body Height , Body Weight , Equipment Design , Female , Humans , Male , Molar/physiology , Orthodontics, Corrective , Regression Analysis , Sex Factors , Somatotypes , Stress, Mechanical , Temporomandibular Joint Disorders/physiopathology , Tooth Loss/physiopathology , TransducersABSTRACT
Maximum bilateral bite force, determined in 129 dental students, was evaluated with regard to six skeletal and eight dental measurements acquired from conventional lateral cephalometric radiographs. Statistically significant correlations for three of the skeletal measurements were found. Maximum bite force increased with regard to decreasing mandibular plane/palatal plane angle and to decreasing mandibular plane angles. Maximum bite force increased with an increasing ratio of posterior facial height to anterior facial height. Significant statistical correlation for only one of the eight dental measurements was found: maximum bite force related directly with increasing maxillary and/or mandibular dentoalveolar heights, and unexpected finding.
