Evaluation of miniscrew-supported rapid maxillary expansion in adolescents: A prospective randomized clinical trial.

OBJECTIVES:: To evaluate and compare the dental and skeletal changes with conventional and miniscrew-supported maxillary expansion appliances in adolescents. MATERIALS AND METHODS:: Forty patients were divided into two groups, with one group receiving a tooth-borne expander and the other group receiving an expander supported by four miniscrews (bone-borne). Multiplanar coronal and axial slices obtained from cone-beam computed tomography images were used to measure the changes in transverse skeletal widths, buccal bone thickness, tooth inclination, and root length. Paired t-tests and independent-sample t-tests were used to compare the two expansion methods. RESULTS:: Bone-borne expansion increased the maxillary suture opening more than 2.5 times than tooth-borne expansion both anteriorly and posteriorly. Between the maxillary first premolars, sutural expansion accounted for 28% and 70% of the total transverse width increase in the tooth-borne and bone-borne expander groups, respectively. Similarly, 26% and 68% of the total expansion was of skeletal nature in the tooth-borne and bone-borne expander groups between the maxillary first molars. The pattern of expansion was variable, with most of the patients in both groups demonstrating a triangular-shaped sutural opening that was wider anteriorly. Subjects in the conventional group experienced significantly more buccal bone reduction and greater buccal inclination of the teeth. No significant differences were observed for root length measurements between the two groups. CONCLUSION:: Use of bone-borne expansion in the adolescent population increased the extent of skeletal changes in the range of 1.5 to 2.8 times that of tooth-borne expansion and did not result in any dental side effects.

Extraction versus non-extraction: evaluation by digital subtraction radiography.

The aim of this study was to investigate the facial profile changes of patients treated with and without extractions of four first premolars using novel computer-based digital subtraction software. The pre- and post-treatment radiographic image pairs of 25 extraction (13 girls and 12 boys, mean age = 12.64 +/- 1.82 years) and 24 non-extraction (12 girls and 12 boys, mean age = 12.48 +/- 1.66 years) Class I patients were subtracted by the software. Student's t-tests were used to determine whether the subtraction values for the linear measurements of radiographic differences registered at various anatomical landmark parameters were statistically different between the groups. To further determine whether any variables related to upper and lower lip changes, regression analyses were performed. The main soft tissue differences between the groups were established at labrale superior, labrale inferior, and sulcus inferior points, with extraction patients showing significantly more retruded upper and lower lips. However, the mean differences between the groups did not exceed 1 mm for these variables. Changes at labrale superior and labrale inferior were associated with sagittal movement of the maxillary (r = 0.549) and mandibular (r = 0.630) incisor midpoints. Changes at sulcus inferior were associated with both sagittal and vertical displacement of mandibular incision point (r = 0.676). Some dentofacial alterations were found but in view of the differences between the groups pretreatment, the inter-group differences reflect different treatment intent rather than differences arising from the extraction and non-extraction modalities.

Smile esthetics: perception and comparison of treated and untreated smiles.

INTRODUCTION: Although orthodontic treatment is based primarily on occlusal relationships, greater attention is now paid to enhancing dentofacial characteristics to produce optimal facial esthetics. The purposes of this study were to compare smile esthetics among extraction and nonextraction patients and a control group, assess certain dentofacial characteristics in those groups, and discuss how these features relate to smile esthetics. METHODS: Panels of orthodontists, plastic surgeons, artists, general dentists, dental professionals, and parents used a 5-point scale to rate smiling photographs of 25 extraction, 25 nonextraction, and 25 untreated control subjects. Dentofacial characteristics of the 3 groups were obtained from lateral cephalometric analyses, direct biometric measurements, and frontal photographs. Smile esthetics and differences among the 3 groups were subjected to 1-way analysis of variance (ANOVA), and Pearson correlation coefficients were calculated to determine the relationship of the variables to the esthetic score. RESULTS: The mean esthetic scores for the extraction, nonextraction, and control groups were 3.15, 3.12, and 3.26, respectively. Visible dentition width relative to the smile width ratio and intercanine distance relative to smile width ratio were significantly different among the groups, with extraction patients showing a slightly wider dental arch relative to the soft tissue (P < .05). There was also a significant difference in the U1-SN angle among the groups (P < .05), and this variable showed a strong correlation with the esthetic score as did maxillary gingival display (P < .05). However, our study groups could not be differentiated in smile esthetics.

Scanning electron microscope study of the effects of soft drinks on etched and sealed enamel.

The purpose of this study was to determine the effects of cola and other acidic drinks on etched tooth enamel in a simulated oral environment. The test beverages were cola, orange soda, lemon soda, and sparkling mineral water. Sixty extracted premolars were divided into an experimental group (n = 40) and a control group (n = 20). Half of the buccal surface of each tooth in the experimental group was coated with wax. The teeth were etched for 60 seconds with 37% phosphoric acid, and half of the teeth were also bonded. The experimental group was further divided into 4 subgroups of 5 teeth each, and each subgroup was exposed to 1 of the test beverages in a thermocycling apparatus. The apparatus was designed to keep the teeth in artificial saliva for 2 hours and in the soft drink at room temperature for 15 minutes. This procedure was performed 3 times a day for 5 days. The control group was also divided into 4 subgroups of 5 teeth each. Half of the buccal surface of each tooth in 2 subgroups was coated with wax, and the teeth in the other 2 were left uncoated. One waxed and 1 unwaxed subgroup were then etched, and the other waxed and unwaxed subgroups were etched and bonded. The waxed subgroups were stored in artificial saliva for 5 days, and the unwaxed subgroups were examined without further exposure to liquids. Surfaces exposed to acidic soft drinks were compared with control surfaces under a scanning electron microscope. Defect zone borders were observed between the exposed areas and the wax-coated areas of teeth in the experimental groups, especially the subgroups exposed to cola, orange soda, and lime soda. Fewer defect zones were observed on teeth exposed to sparkling mineral water. The results indicate that acidic soft drinks cause enamel demineralization on etched tooth surfaces.