Sagittal airway changes: rapid palatal expansion versus Le Fort I osteotomy during maxillary protraction.

The purpose of the present study was to evaluate upper airway changes related to craniofacial changes induced by a facemask (FM) combined with Le Fort I osteotomy without down-fracture in Class III maxillary retrusion subjects (group 1) when compared with a similar group of subjects treated with traditional rapid palatal expansion and FM therapy. Pre- (T1) and post- (T2) protraction cephalometric radiographs of group 1 (10 females and 6 males; mean age 12.75 ± 1.91 years) and group 2 (7 females and 9 males; mean age 12 ± 1.7 years) were traced. The treatment duration was 149 ± 14 days (approximately 5 months) and 270 ± 46 days (approximately 9 months) for groups 1 and 2, respectively. A paired t-test for intergroup comparisons of values at T1, an independent samples t-test for intragroup comparisons of values at T1 and T2, and a non-parametric Mann-Whitney U-test for intergroup comparisons were used. To evaluate the relationship between changes in upper airway dimension and craniofacial morphology, a multiple-regression analysis was performed. Significant maxillary protraction along with clockwise rotation of the mandible was achieved in both groups. Counter-clockwise maxillary rotation was significant in group 1 (P < 0.05) but not in group 2. While nasopharyngeal measurements (PNS-ad1, PNS-ad2) showed significant increases (P < 0.05) as a result of treatment in both groups, oropharyngeal measurements did not change. Maxillary protraction, which was achieved in both groups but in a shorter period of time in group 2, improved nasopharyngeal but not oropharyngeal airway dimensions.

Effect of short curing times with a high-intensity light-emitting diode or high-power halogen on shear bond strength of metal brackets before and after thermocycling.

OBJECTIVE: To test the hypothesis that short curing times using a high-intensity light-emitting diode (LED) or high-power halogen are not associated with compromised shear bond strength (SBS) of metal brackets before and after thermocycling. MATERIALS AND METHODS: Two hundred forty extracted human premolar teeth were divided into six groups of 40 each. Metal brackets were bonded using a light-cured composite (Transbond XT). In group 1 a conventional halogen light (Hilux) was used for 40 seconds. In groups 2, 3, and 4 a high-power halogen light (Swiss Master) was used for 2, 3, and 6 seconds, respectively. In groups 5 and 6 a high-intensity LED (Bluephase) was used for 10 and 20 seconds, respectively. After bonding, half of the specimens in each group were thermocycled, and all specimens were tested for SBS. After debonding, the bracket bases and the enamel surfaces were scored according to the Adhesive Remnant Index. RESULTS: Two-way analysis of variance detected significant differences in SBS values with respect to curing method (type of light-curing unit and curing time) (P  =  .0001) and thermocycling (P  =  .01). Tukey post hoc analysis showed that with or without thermocycling the mean SBS values of groups 1, 4, 5, and 6 were not significantly different, whereas group 2 showed the lowest SBS values. The predominant failure site for groups 2 and 3 was between the bracket and the adhesive and for groups 4, 5, 6 it was at the tooth/adhesive interface. CONCLUSION: Curing time can be reduced to 6 seconds with high-power halogen light and to 10 seconds with high-intensity LED without compromising in vitro SBS of metal brackets.

A comparative evaluation of casein phosphopeptide-amorphous calcium phosphate and fluoride on the shear bond strength of orthodontic brackets.

The purpose of the study was to evaluate and compare the effects of topical application of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and fluoride on the shear bond strength (SBS) of orthodontic brackets bonded to human premolar teeth. Eighty extracted human premolar teeth were cleansed of soft tissue, then polished with non-fluoridated pumice, and immersed in water for 1-3 months until testing. The teeth were randomly divided into four groups: group 1, control, without pre-treatment of the enamel; group 2, the enamel was treated with 5 per cent sodium fluoride varnish for 4 minutes; group 3, the enamel was treated with CPP-ACP for 3 minutes; and group 4, the enamel was treated with 5 per cent sodium fluoride and CPP-ACP. All bonded specimens were immersed in distilled water at room temperature for 24 hours and subsequently tested for SBS in a universal testing machine. After debonding, the bracket bases and the enamel surfaces were examined by eye to assess any adhesive remaining, in accordance with the Adhesive Remnant Index (ARI). Descriptive statistics were calculated for each group. Analysis of variance and Tukey honestly significant difference (HSD) test were performed to compare the SBS of the groups. The chi-square test was used to evaluate differences in ARI scores between the groups. The SBS in group 2 was significantly lower than groups 1, 3, and 4 (P < 0.001). ARI scores were not significantly different between the four groups (P > 0.05). CPP-ACP, either alone or combined with fluoride, may safely be used as a prophylactic agent before bracket bonding.

Cephalometric evaluation of molar distalization by hyrax screw used in conjunction with a lip bumper.

AIM: To determine the treatment effects of the Hyrax screw, when used with a lip bumper appliance, on the distalization of maxillary molars and the reciprocal effects on the anchor premolars and maxillary incisors. METHODS: Records, including study casts, lateral cephalometric radiographs, extra- and intraoral photographs of 9 patients were taken at the start of treatment and after distalization was achieved. Wilcoxon signed rank test was performed to analyze the skeletal and dental changes. RESULTS: During the active period of maxillary molar distalization, the maxillary incisors significantly proclined by 5.89 degrees (P <.05), 5.39 degrees (P <.05), and 1.72 mm (P <.05) relative to the SN, RH, and RV planes, respectively. The maxillary first molars showed significant distal crown tipping, as evidenced by 4.61-degree (P = .00), 4.17-mm (P = .00), and 1.11-mm (P = .02) decreases in U6-RH angle, U6 perpendicular RV, and U6 perpendicular RH distances respectively. Anchorage loss, with 4.17 mm mesial movement of the maxillary second premolars, was significant (P = .01). CONCLUSION: When selecting the appropriate method for maxillary molar distalization, anchorage loss potential, the need for patient compliance, and the duration of treatment should be considered.

Longitudinal changes in craniofacial factors among snoring and nonsnoring Bolton-Brush study participants.

The extent to which craniofacial risk factors are manifested from childhood in habitual snorers and those with obstructive sleep apnea hypopnea syndrome (OSAHS) is unknown. The purpose of this study was to examine the differences in craniofacial factors between snorers and nonsnorers from childhood to adulthood. The sample consisted of 80 Bolton-Brush subjects (men, 52%; white, 100%) recalled at adult ages (53-78 years) who had existing prepubertal (age, 4-5 years) and pubertal (age, 12-13 years) records. Snoring was assessed at the adult age through subjective and spousal reports. Cephalometric radiographs were used to characterize 13 craniofacial hard and soft tissue measurements. The t tests revealed that there was a trend (P <.10) for longer hyoid-to-mandibular plane distance at prepubertal and pubertal ages and significant (P <.05) differences at adult recall for snorers. Posterior airway space was significantly smaller for snorers at adult recall. The longitudinal analysis did show a significant change in 9 craniofacial variables over time, but this change was not different between snorers and nonsnorers. We concluded that snorers exhibit a lowered hyoid position from childhood and that longitudinal changes must be explored further with a larger sample.

A comparative analysis of maxillary tooth movement produced by cervical headgear and pend-x appliance.

The purpose of this study was to compare the effects of cervical headgear and pend-x on the maxillary first molar, second molar, first premolar, and upper incisors. Cephalometric radiographs were obtained at the start of treatment (T1) and after molar distalization was completed (T2) for 13 patients in a pend-x group and 13 patients in a cervical headgear group. The changes of the maxillary teeth were measured on maxillary superimpositions. Nonparametric Mann-Whitney U-test was used to compare the mean differences between the two groups. The mean amount of distalization for the headgear group was 3.15 +/- 1.94 mm and that for the pend-x group was 3.81 +/- 2.25 mm. The second molar teeth were also distalized to a mean amount of 2.27 +/- 1.33 mm in the headgear group and 2.04 +/- 2.15 mm in the pend-x group. The mean treatment time for distalization was 11.38 +/- 3.18 months for the headgear group and 7.31 +/- 4.09 months for the pend-x group. During distalization, the maxillary molars tipped distally in both groups, but intergroup differences were not significant. The anterior inclinations of the first premolar and upper incisor increased significantly in the pend-x group (P < .01). Maxillary molars showed no vertical movement in the pend-x group but extruded in the headgear group (P < .01). The anchorage loss of the pend-x appliance as well as the necessary patient compliance and greater treatment time with the cervical headgear should be taken into consideration.

Orthognathic surgery outcome analysis: 3-dimensional landmark geometric morphometrics.

Traditional cephalometric analysis of 2-dimensional (2D) landmarks has been limited to distances, indices, and angles. Quantitative results vary depending on what baseline is chosen. Geometric morphometric techniques, such as Procrustes superimposition, assume all landmarks carry equivalent information. Using these methods, landmark coordinates (x, y, z) facilitate comparison of patients and "normative"shapes and assessment of pre- to postoperative outcomes. Pre- and postoperative lateral and frontal cephalograms and stereophotograms were taken of a 48-year-old Caucasian man and a 38-year-old Caucasian woman. Coordinates of 3D hard tissue landmarks were collected directly from scanned cephalograms, and 3D soft tissue landmarks were collected onscreen. Procrustes superimpositions of pre- and postoperative 3D craniodental landmark coordinates and 3D soft tissue coordinates were made, and scatter plots were created to show the surgical shape change separately for each patient. Procrustes superimposition of the preoperative and "normative craniodental data (18-year-old male and female Bolton standards) provided both qualitative and quantitative evaluations of the patients, allowing a better determination of the required treatment. Unlike traditional baseline-dependent methods, Procrustes shape analysis produces a single useful measure of surgical shape change or comparison to normative shape.