Long-term stability of rapid palatal expander treatment and edgewise mechanotherapy.

Previous studies on long-term stability of orthodontic treatment primarily have focused on the stability of the lower arch treated with edgewise appliances. The aim of this study was to evaluate the long-term stability of the upper and the lower dental arches of patients treated with a rapid palatal expander. The sample comprised of 165 dental casts randomly selected from patients who had been out of retention for 8 to 10 years at a mean age of 30 years. Measurements were made directly on dental casts obtained at the three time intervals: before treatment, after treatment, and after retention. Differences over time between the upper and the lower dental arches and between intervals were analyzed by a two-way multivariate analysis of variance (MANOVA) and post hoc Bonferroni t tests. Differences between after treatment and after retention were statistically significant (P < 0.006) for all except lower intermolar width. However, only for lower and upper arch lengths and perimeters were the differences greater than 2.0 mm. Treatment with the rapid palatal expander presented good stability for upper intercanine width, upper and lower intermolar widths and incisor irregularity. Lower intercanine, arch length, and perimeter presented poor stability.

The validity of maxillary expansion indices.

Numerous indices have been proposed to help the clinician decide how much maxillary expansion will be required to alleviate crowding. The purpose of this investigation was to examine the validity of Pont's index, Schwarz's analysis and McNamara's rule of thumb. Records of 40 patients (20 females and 20 males) were selected from 155 consecutive pretreatment records. The discrepancy between actual intermolar/interpremolar widths and the index-generated widths were correlated against measures of crowding, and linear regressions were computed. Statistical analysis revealed that (1) males had more significant correlations between arch width and crowing than females, (2) interpremolar widths were more strongly correlated than intermolar widths, (3) Pont's index and McNamara's rule of thumb overestimated required arch width by 2.5 mm to 4.7 mm and 2.7 mm to 3.7 mm respectively, and (4) Schwarz's analysis overestimated interpremolar width by 2.5 mm to 4.3 mm but was reasonably accurate for intermolar width in males. The results suggest that these indices potentially overestimate the arch expansion required to alleviate crowding.

The validity of the prediction of Soft Tissue profile changes after LeFort I osteotomy using the dentofacial planner (computer software).

The purpose of this study was to examine the validity of the prediction of soft tissue changes after LeFort I osteotomy with the DentoFacial Planner (DFP) (computer software). The preoperative and postoperative lateral cephalograms of 21 white adult orthodontic patients (10 males and 11 females) who underwent only LeFort I osteotomy as part of their overall treatment were digitized. A coordinate system of X and Y axes were used to assess the amount and direction of movement of the maxilla. The SN + 7 degrees was the X axis, and a perpendicular to this plane from nasion was the Y axis. The sample was divided into two groups depending on the amount of forward movement of the maxilla. More than 2 mm of anterior placement of the maxilla comprised the advancement group (13 patients) and less than 2 mm comprised the impaction group (8 patients). The selection criteria for the sample were (1) before and after cephalograms taken with lips in repose and in centric occlusion; (2) all preoperative records taken almost immediately before surgery; (3) postoperative records taken at least 6 months after surgery and checked by regional superimposition of the preoperative and postoperative lateral cephalograms onto the maxilla and the mandible. No tooth movement occurred between the time the records were taken. The following soft tissue landmarks were examined: pronasale, subnasale, stomion superior, middle upper lip, stomion inferior, middle lower lip, labrale inferior, labiomental fold, and pogonion. The results indicate that for some of these landmarks the amount and direction of soft tissue changes differed between the DFP prediction and the actual surgical changes by LeFort I osteotomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Integumental profile changes after surgical orthodontic correction of bimaxillary dentoalveolar protrusion in black patients.

An investigation was undertaken to evaluate the soft-tissue changes of the lips as a result of dentoalveolar setback procedures performed to reduce bimaxillary dentoalveolar protrusion in black patients. Lateral head films of 14 adult patients taken preoperatively and postoperatively were compared to evaluate soft- and hard-tissue changes. A stepwise regression analysis with hard-tissue changes, initial interlabial gap, lip thickness, and lip area as predictor variables was performed to assess their influence on the change in an associated soft-tissue point. Upper lip thickness and horizontal change in PR accounted for 60% of the horizontal variance in the upper lip at SLS, and horizontal change in PR accounted for 80% of the horizontal variance in LS. Lower lip area accounted only for 28% of the horizontal variance in the lower lip at LI. Vertical changes of the upper lip were small and could not be predicted. Vertical changes of the lower lip were small but predictable: IL and lip thickness accounted for 75% of the vertical variance in the lower lip at ILS, and ID accounted for 58% of the vertical variance in LI.

Mandibular growth changes and maturation of cervical vertebrae--a longitudinal cephalometric study.

The relationship of cervical vertebral maturation and mandibular growth changes are assessed in annual lateral cephalometric radiographs of thirteen caucasian females from 9 to 15 years of age. Statistically significant increases in mandibular length, corpus length and ramus height are associated with specific maturation stages in the cervical vertebrae.

Skeletal age assessment using the first, second, and third fingers of the hand.

The purpose of this study was to determine whether skeletal age assessments using the first, second, and third fingers of the hand are as valid as those using the entire hand-wrist. Previous studies have demonstrated that treatment can be better oriented to the unique physiologic characteristics of the individual if skeletal age is used to assess maturational status. The sample was selected from the files of the Bolton-Brush Foundation and consisted of radiographs of 19 male and 20 female subjects whose yearly hand-wrist radiographs were available covering the age span of 10 to 16 years for girls and 12 to 18 years for male subjects. Two maturity indicators, the sesamoid and the epiphyseal-diaphyseal stages of ossification, were evaluated. Reliability of the method was tested by the t test for paired comparisons and the Pearson product-moment correlation. To determine the validity of the method, an analysis of variance (ANOVA) was used. In addition, the Pearson product-moment correlations between the two methods were performed and the 95% confidence intervals for mean differences for each sex and time were calculated. As indicated by the ANOVA, the two methods differed by a statistically significant amount, with the three-fingers assessments being slightly more advanced than the hand-wrist assessments. Although they differed, for the male subjects, the three-fingers method never deviated from that of the hand-wrist by more than 2.89 months with a minimum deviation of 0.32 months. For the female subjects, the maximum deviation was 4.45 months with a minimum of 1.55 months.(ABSTRACT TRUNCATED AT 250 WORDS)

A longitudinal growth study: maxillary length at puberty in females.

1. A great individual variability is present in the timing of the maximum increment in ANS-PNS. 2. The maximum increment in maxillary length occurred before, as well as after, menarche, onset of epiphyseal-diaphyseal fusion, and peak of growth in height. 3. The later the maximum increment of growth occurred, the earlier menarche and onset of fusion occurred in relation to the peak. 4. The amount of growth at peak and duration of growth were not dictated by the absolute size of the maxilla at peak. 5. There was no significant difference in the amount of growth of maxillary length before or after menarche. 6. Timing of maximum increment in maxillary length was weakly correlated with onset of epiphyseal-diaphyseal fusion and menarche.