The Hyrax appliance with tooth anchorage variations in surgically assisted rapid maxillary expansion: a finite element analysis.

PURPOSE: It is known that a correct transverse maxillary dimension is a key factor for a stable occlusion, which brings functional and esthetic benefits for the patient. In patients presenting maxillary atresia and the completion of bone growth, a highly recommended option for correction is the surgically assisted rapid maxillary expansion (SARME) associated with the Hyrax appliance. The objective of this study was to evaluate the influence of tooth anchorage variations of the Hyrax appliance in SARME through finite element analysis, evaluating which anchorage option might be associated with more effective orthopedic results with less undesired side effects. METHODS: Five different dental anchoring conditions for the Hyrax appliance were simulated through FE analysis applying premolars and molars as anchorage, having the same force applied by the activation of the Hyrax screw (0.5 mm) in all groups. The maxillary displacement results (axes X, Y, and Z) and generated stresses for both teeth and maxillary bone were calculated and represented using a color scale. RESULTS: All groups presented significant bone displacement and stress concentration on anchoring teeth, with the group presenting anchorage in the 1st and 2nd molars showing the greatest maxillary horizontal displacement (axis X) and suggesting the lowest tendency of dental vestibular inclination. CONCLUSIONS: Variations in dental anchorage might substantially affect the maxillary bone and teeth displacement outcome. The protocol for the Hyrax apparatus in SARME applying the 1st and 2nd molars as anchorage might generate less tilting and inclination of the anchoring teeth.

Immediate effects of rapid maxillary expansion with Haas-type and hyrax-type expanders: a randomized clinical trial.

INTRODUCTION: The purposes of this study were to evaluate and compare the immediate effects of rapid maxillary expansion (RME) in the transverse plane with Haas-type and hyrax-type expanders by using cone-beam computed tomography. METHODS: A sample of 33 subjects (mean age, 10.7 years; range, 7.2-14.5 years) with transverse maxillary deficiency were randomly divided into 2 groups: Haas (n = 18) and hyrax (n = 15). All patients had RME with an initial activation of 4 quarter turns followed by 2 quarter turns per day until the expansion reached 8 mm. Cone-beam computed tomography scans were taken before expansion and at the end of the RME phase. Maxillary transversal measurements were compared by using the mixed analysis of variance (ANOVA) model and the Tukey-Kramer method. RESULTS: RME increased all maxillary transverse dimensions (P <0.0001). There was less expansion at skeletal than dental levels. The hyrax group had greater statistically significant orthopedic effects and less tipping tendency of the maxillary first molars compared with the Haas group. CONCLUSIONS: Both appliances were efficient in correcting a transverse maxillary deficiency. The pure skeletal expansion was greater than actual dental expansion. The hyrax-type expander produced greater orthopedic effects than did the Haas-type expander, but this effect was less than 0.5 mm per side and might not be clinically significant.

Oral health-related quality of life in women with temporomandibular joint disk anterior displacement before and after disk repositioning and anchoring surgery assessed with the Oral Health Impact Profile (OHIP-14).

OBJECTIVES: The aim of this study was to assess and compare oral health-related quality of life (OHRQOL) in women with temporomandibular joint (TMJ) disk displacement without reduction, before disk repositioning and anchoring surgery, in short-term follow-up, in different age groups, and with use of the Oral Health Impact Profile (OHIP-14). STUDY DESIGN: Fifty women ages between 17 and 60 years were divided into 4 age groups: 17-27, 28-38, 39-49, and 50-60 years. All the patients were asked to answer the OHIP-14 form before surgery and during their short-term follow-up. Seven domains of OHRQOL were rated on a 5-point Likert scale from 0 (never) to 4 (very often). Domains' scores and total OHIP-14 were compared between times by using Student's t test in the whole sample and in the 4 age groups. RESULTS: Both the whole sample and the age groups (17-27, 28-38, 39-49 years) showed a statistically significant decrease in all scores (P < .01). The age group 50-60 years showed a decrease in scores significant only in functional limitation (P = .05) CONCLUSIONS: TMJ disk anterior displacement had a negative impact on women's OHRQOL because of physical pain, physical disability, and psychological discomfort. TMJ disk repositioning and anchoring surgery improved overall OHRQOL in patients between 17 and 49 years of age; however, in patients between 50 and 60 years of age, there was improvement only in physical pain.

Soft-tissue changes during facial growth in skeletal Class II individuals.

INTRODUCTION: In orthodontic treatment, a harmonious soft-tissue profile can be difficult to achieve; the thickness of the soft tissues can vary greatly, and changes with growth and treatment can be difficult to predict. The purpose of this study was to investigate changes in the thickness and the length of the soft tissues of the nose, upper and lower lips, and chin due to growth from 6 to 16 years of age. METHODS: Cephalograms of 36 subjects (22 boys, 15 girls) with skeletal Class II malocclusions were analyzed. They participated in the Burlington Growth Study, and longitudinal records had been collected at ages 6, 9, 12, 14, and 16 years. The cephalograms were digitized and analyzed with Dentofacial Planner Plus (version 2.0; Dentofacial Software, Toronto, Ontario, Canada) software. Statistical analysis was performed with the nonparametric Friedman test, and comparisons among means were made with 1-way ANOVA software. RESULTS: All structures showed some growth at all stages. The nose showed the greatest increases in thickness and length in both sexes. There was sexual dimorphism at 16 years, with higher values for boys. Upper lips tended to reduce in the girls. Upper lip length showed slight increases, and base of the upper lip showed small increases for both sexes. The lower lip had moderate increases in all measurements, and its thickness showed sexual dimorphism at almost all ages. The soft tissues of the chin increased in both thickness and length, with no sexual dimorphism.

Change in the pulp chamber temperature with different stripping techniques.

BACKGROUND: The aim of this study is to evaluate the change in pulp chamber temperature during the stripping technique. METHODS: Seventy-eight proximal surfaces of 39 extracted human teeth were stripped by two techniques: double-sided perforated stripping disk (PSD) and handheld stripper (HS). The teeth were divided into three groups: incisors (group 1), premolars (2), and molars (3). A J type thermocouple was inserted into the pulp chamber for temperature evaluation during the stripping procedure. RESULTS: Temperature rise was observed in all groups. The average temperature increase for the incisors was 2.58°C (±0.27°C) with PSD and 1.24°C (±0.3°C) with HS; for the premolars, 2.64°C (±0.29°C) with PSD and 0.96°C (±0.39°C) with HS; and for the molars, 2.48°C (±0.38°C) with PSD and 0.92°C (±0.18°C) with HS. There was significant difference (p<0.001) in pulp temperature variation among the stripping techniques evaluated. Greater variations in the temperature were observed for the stripping technique with PSD for all groups (3.1°C in incisors and premolars, 3.2°C in molars). Stripping performed with HS had minor differences in pulp temperature (1.7°C in incisors, 1.9°C in premolars, and 1.2°C in molars) than those in PSD group. However, the temperature variation was less than the critical threshold (5.5°C) in all groups. The results for teeth group comparison showed no significant difference in the temperature variation. CONCLUSIONS: The stripping technique with PSD produced significant increase in pulp temperature, with no differences between the types of teeth. However, it may not be clinically relevant, and both stripping techniques can be used safely.

Indirect bonding with thermal glue and brackets with positioning jigs.

In orthodontics the precise location of bracket placement on the teeth is a goal in order to individualize and optimize treatment outcome. The authors will describe the indirect bonding procedure with thermal glue transfer tray and brackets with positioning jigs for precise bracket placement.