Evaluation of rotational control and forces generated during first-order archwire deflections: a comparison of self-ligating and conventional brackets.

The purpose of this study was to compare the activation and deactivation forces generated during first-order archwire deflections when different sizes and types of NiTi wires are paired with conventional and self-ligating brackets (SLBs) and to evaluate the rotational control between these same archwire and bracket combinations. Four maxillary premolar SLBs (Damon 3MX, SmartClip, Carriere, and In-Ovation R) and one conventional twin bracket (Victory) were paired with seven archwires [0.014, 0.016, 0.018, 0.016 × 0.022 Ultra Therm (thermal A f 80-90°F), 0.016, 0.018 SPEED Supercable, and 0.017 × 0.025 Turbo]. A cantilever test design was used and 10 trials per bracket/archwire combination were performed. Load/deflection data were captured over 4 mm fi rst-order archwire deflections. Forces generated were compared across all bracket/archwire combinations. Among thermal archwires, for a given deflection, forces increased with increasing archwire size. Supercable archwires displayed less force than their same size thermal counterparts. The Turbo archwire generated force values in between those of 0.016 and 0.018 thermal archwires. Rotational control improved with increasing wire dimensions and for a given archwire size. Rotational control among brackets generally ranked as follows: In-Ovation R > SmartClip > Carriere and Damon 3MX.

A prospective comparative study between differential moments and miniscrews in anchorage control.

The purpose of this study was to measure the efficacy of anchorage control between differential moments mechanics and temporary anchorage devices in a clinical trial. Forty-six patients requiring extraction of maxillary first premolars were allocated into 2 treatment groups. The differential moments group (G1) received a nickel titanium (NiTi) intrusion arch and a 150g NiTi closing coil spring for separate canine retraction, followed by a continuous mushroom loop archwire for the retraction of the incisors. The TAD group (G2) received one miniscrew placed between maxillary second premolars and first molars with a 150 g NiTi closing coil spring connecting the miniscrew to a hook placed in the archwire between the lateral incisor and canine. Lateral cephalograms were taken before (T1) and after incisor retraction (T2). The ratio of molar protraction to incisor retraction was calculated and intragroup and intergroup changes in upper lip, maxillary incisor and molar position were analyzed by paired and independent t-tests. Twenty-eight patients were analyzed after 18 patients did not receive the intervention, were lost to follow-up, or discontinued treatment. The ratio of molar protraction to incisor retraction in G1 was 0.44 and in G2 was -0.11, which was significantly different. There was a statistically significant change in upper lip from T1 to T2 but no difference between the two groups. Moreover, there was a significant distal molar tipping and lingual incisor tipping in G2. There is a significant difference in the amount of anchorage control using differential moments mechanics compared to TADs. Although statistically significant retraction of upper lip was observed in both groups, there was no significant difference between the two groups.

Alveolar ridge width and height changes after orthodontic space opening in patients congenitally missing maxillary lateral incisors.

The purpose of this study was to evaluate the dimensional changes of the alveolar ridge in patients with congenitally missing maxillary lateral incisors. The width and height of the alveolar ridge were compared before and after opening space for an endosseous dental implant between the central incisor and canine. Pre- and post-treatment dental stone models of 31 patients (8 males, 23 females; mean age 15.1 ± 7.9 years pre-treatment, 17.6 ± 8 years post-treatment) with unilaterally or bilaterally, congenitally missing maxillary lateral incisors were used in this study. Pre- and post-treatment measurements included: the space between the maxillary central incisor and canine, the depth of the labial concavity, and the width and height of the lateral incisor alveolar ridge. Two different techniques were used to measure the ridge width. Student's paired samples t-test was used to test for significance. The alveolar ridge underwent statistically significant width loss (Method 1: 4-8 per cent, Method 2: 13-15 per cent) during the course of orthodontic treatment. A 6-12 per cent loss in ridge height was also noted. The depth of the labial concavity between the maxillary central incisor and canine nearly doubled. There was a significant decrease in the width and height of the alveolar ridge in patients congenitally missing a maxillary lateral incisor who received orthodontic treatment to create space for an endosseous dental implant.

Microdamage of the cortical bone during mini-implant insertion with self-drilling and self-tapping techniques: a randomized controlled trial.

INTRODUCTION: The purpose of this research was to evaluate microdamage accumulation after mini-implant placement by self-drilling (without a pilot hole) and self-tapping (screwed into a pilot hole) insertion techniques. The null hypothesis was that the mini-implant insertion technique would have no influence on microcrack accumulation and propagation in the cortical bones of the maxillae and mandibles of adult hounds. METHODS: Mini-implants (n = 162; diameter, 1.6 mm; length, 6 mm) were placed in the maxillae and mandibles of 9 hounds (12-14 months old) with self-drilling and self-tapping insertion techniques. The techniques were randomly assigned to the left or the right side of each jaw. Each hound received 18 mini-implants (10 in the mandible, 8 in the maxilla). Histomorphometric parameters including total crack length and crack surface density were measured. The null hypothesis was rejected in favor of an alternate hypothesis: that the self-drilling technique results in more microdamage (microcracks) accumulation in the adjacent cortical bone in both the maxilla and the mandible immediately after mini-implant placement. A cluster level analysis was used to analyze the data on the outcome measured. Since the measurements were clustered within dogs, a paired-samples t test was used to analyze the average differences between insertion methods at both jaw locations. A significance level of 0.05 was used for both analyses. RESULTS: The self-drilling technique resulted in greater total crack lengths in both the maxilla and the mandible (maxilla: mean difference, 18.70 ± 7.04 µm/mm(2); CI, 13.29-24.11; mandible: mean difference, 22.98 ± 6.43 µm/mm(2); CI, 18.04-27.93; P <0.05), higher crack surface density in both the maxilla and the mandible (maxilla: mean difference, 10.39 ± 9.16 µm/mm(2); CI, 3.34-17.43; mandible: mean difference, 11.28 ± 3.41 µm/mm(2); CI, 8.65-13.90; P <0.05). CONCLUSIONS: This study demonstrated greater microdamage in the cortical bones of adult hounds in both the maxilla and the mandible by the self-drilling insertion technique compared with the self-tapping technique.

Program ratings do not predict negative content in commercials on children's channels.

OBJECTIVE: The aim of this study was to determine the presence of negative content in commercials airing on 3 children's channels (Disney Channel, Nickelodeon, and Cartoon Network). METHOD: The 1681 commercials were coded with a reliable coding system and content comparisons were made. RESULTS: Although the majority of the commercials were coded as neutral, negative content was present in 13.5% of commercials. This rate was significantly more than the predicted value of zero and more similar to the rates cited in previous research examining content during sporting events. The rate of negative content was less than, but not significantly different from, the rate of positive content. Thus, our findings did not support our hypothesis that there would be more commercials with positive content than with negative content. Logistic regression analysis indicated that channel, and not rating, was a better predictor of the presence of overall negative content and the presence of violent behaviors. Commercials airing on the Cartoon Network had significantly more negative content, and those airing on Disney Channel had significantly less negative content than the other channels. Within the individual channels, program ratings did not relate to the presence of negative content. CONCLUSION: Parents cannot assume the content of commercials will be consistent with the program rating or label. Pediatricians and psychologists should educate parents about the potential for negative content in commercials and advocate for a commercials rating system to ensure that there is greater parity between children's programs and the corresponding commercials.

Skeletal and dental asymmetries in Class II subdivision malocclusions using cone-beam computed tomography.

INTRODUCTION: The objective of this study was to compare the degrees of skeletal and dental asymmetry between subjects with Class II subdivision malocclusions and subjects with normal occlusions by using cone-beam computed tomography. METHODS: Thirty subjects with Angle Class II subdivision malocclusions (mean age, 13.99 years) and 30 subjects with normal occlusions (mean age, 14.32 years) were assessed with 3-dimensional cone-beam computed tomography scans. Independent t tests were used to compare orthogonal, linear, and angular measurements between sides and between groups. RESULTS: Total mandibular length and ramus height were shorter on the Class II side. Pogonion, menton, and the mandibular dental midline were deviated toward the Class II side. Gonion and the anterior condyle landmark were positioned more posteriorly on the Class II side. The mandibular dental landmarks were located more latero-postero-superiorly, and the maxillary dental landmarks more latero-antero-superiorly on the Class II side. There was loss of maxillary arch length, and the mandibular molar was closer to the ramus on the Class II side. CONCLUSIONS: The etiology of Class II subdivision malocclusions is primarily due to an asymmetric mandible that is shorter and positioned posteriorly on the Class II side. A mesially positioned maxillary molar and a distally positioned mandibular molar on the Class II side are also minor contributing factors.

The relationship of facial anatomic landmarks with midlines of the face and mouth.

STATEMENT OF PROBLEM: The importance of the midline is well known to dentists. Currently, there are no verifiable guidelines that direct the choice of specific anatomic landmarks to determine the midline of the face or midline of the mouth. PURPOSE: The purpose of this study was to determine the hierarchy of facial anatomic landmarks closest to the midline of the face as well as midline of the mouth. MATERIAL AND METHODS: Three commonly used anatomic landmarks, nasion, tip of the nose, and tip of the philtrum, were marked clinically on 249 subjects (age range: 21-45 years). Frontal full-face digital images of the subjects in smile were then made under standardized conditions. A total of 107 subjects met the inclusion criteria. Upon applying exclusion criteria, images of 87 subjects were used for midline analysis using a novel concept called the Esthetic Frame. Deviations from the midlines of the face and mouth were measured for the 3 clinical landmarks; the existing dental midline was considered as the fourth landmark. The entire process of midline analysis was done by a single observer and repeated twice. Reliability analysis and 1-sample t tests were conducted at alpha values of .001 and .05, respectively. RESULTS: The results indicated that each of the 4 landmarks deviated uniquely and significantly (P<.001) from the midlines of the face as well as the mouth. CONCLUSIONS: Within the limitations of the study, the hierarchy of anatomic landmarks closest to the midline of the face in smile was as follows: the midline of the oral commissures, natural dental midline, tip of philtrum, nasion, and tip of the nose. The hierarchy of anatomic landmarks closest to the midline of the oral commissures was: natural dental midline, tip of philtrum, tip of the nose, and nasion. These relationships were the same for both genders and all ethnicities classified.

Barriers to care-seeking for children's oral health among low-income caregivers.

OBJECTIVES: We identified psychosocial, structural, and cultural barriers to seeking dental care among nonutilizing caregivers of Medicaid-enrolled children. METHODS: We used Medicaid utilization records to identify utilizing and nonutilizing African American and White caregivers of Medicaid-enrolled children in Jefferson County, Kentucky. We conducted 8 focus groups (N=76) with a stratified random sample of responding caregivers; transcripts were qualitatively analyzed. RESULTS: Psychosocial factors associated with utilization included oral health beliefs, norms of caregiver responsibility, and positive caregiver dental experiences. Utilizing groups reported higher education; health beliefs included identifying oral health with overall health and professional preventive dental care with caregiver responsibility for children's overall health. These beliefs may mediate shared structural barriers, including transportation, school absence policies, discriminatory treatment, and difficulty locating providers who accept Medicaid. Expectation of poor oral health among some low-income caregivers was among factors identified with nonutilization. CONCLUSIONS: Disadvantaged caregivers reported multiple barriers to accessing dental care for their children. Providers, Medicaid administrators, and schools must coordinate steps to encourage caregiver-controlled dental care, build trust, and link professional preventive dental care with caregiver responsibility for children's overall health.

Clinically prescribed orthoses demonstrate an increase in velocity of gait in children with cerebral palsy: a retrospective study.

The purpose of this study was to determine the effect clinically prescribed ankle-foot orthoses (AFOs) have on the temporal-spatial parameters of gait, as compared with barefoot walking in children with cerebral palsy. A retrospective chart review of data collected between 1995 and 1999 in our motion analysis laboratory was performed. A retrospective chart review of 700 patients revealed 115 patients (mean age 9 years) who had a primary diagnosis of CP (diplegia n=97, hemiplegia n=18). All were wearing clinically prescribed hinged or solid AFOs at the time of undergoing a three dimensional gait analysis. In line with our standard clinical practice, data for both conditions (braced and barefoot walking) were collected the same day by the same examiner. Statistical analyses indicated the temporal and spatial gait parameters of velocity, stride length, step length, and single limb stance were significantly increased (p<0.001) with the use of AFOs versus barefoot walking. Cadence was the only parameter found to not be statistically different.