Long-term effectiveness of the continuous and the sectional archwire techniques in leveling the curve of Spee.

INTRODUCTION: The correction of a deep overbite with the subsequent achievement of long-term stability is a difficult problem for orthodontists. The role of leveling the curve of Spee (COS) in bite opening and the success of orthodontic treatment has been well documented in the literature. The aim of this study was to investigate whether leveling the COS, by using 2 orthodontic treatment techniques, produces stable results on a long-term basis. METHODS: We compared the long-term stability of leveling the COS with the straight-wire Alexander technique and the bioprogressive sectional-arch technique. The randomly selected subjects for this retrospective study were obtained from the private practices of Drs R. G. Alexander and Ruel Bench. Study models taken 2 months before treatment (T1), 2 months after treatment (T2), and after retention (T3) were evaluated. Measurements of the COS were made on the mandibular casts with a commercially available palatometer. Mandibular intercanine width, overbite, overjet, mandibular incisor irregularity, and mandibular arch length were also recorded. RESULTS AND CONCLUSIONS: Both techniques produced highly significant reductions in the COS (T1 to T2). Statistically significant, but clinically insignificant, postretention relapse of the COS occurred (T2 to T3). For both techniques, a statistically significant difference was seen in the incidence of the relapse of the COS between patients who were completely leveled posttreatment and those who were not. We did not find a correlation between pretreatment COS and relapse in any of the other occlusal traits studied.

Malocclusion as a risk factor in the etiology of headaches in children and adolescents.

INTRODUCTION: The purpose of this study was to determine the importance of occlusal factors in recurrent headaches in children and adolescents without other signs or symptoms of temporomandibular disorders or related craniomandibular disorders. METHODS: A sample of 50 children and adolescents, ages 8 to 16, who reported headaches was obtained from the University at Buffalo Orthodontic Clinic records; a control group of 50 children and adolescents, matched for age and sex, was also obtained. Plaster models, made during the routine collection of orthodontic records, were used to obtain the following occlusal trait measurements: Angle classification, overjet, anterior and posterior crossbite, scissors-bite, overbite, open bite, dental midline discrepancy, crowding, spacing, and dental development stage. RESULTS: Overbite, overjet, and posterior crossbite showed statistically significant associations (chi-square) with increased risk for headaches. Logistic regression analysis demonstrated that overjet was a significant factor only because of its correlation with overbite and posterior crossbite. Overjet was not significant after adjusting for the other 2 variables, whereas overbite and posterior crossbite were associated with significantly increased risk (>3:1) of headache. The combination of 2 or more of these 3 occlusal factors increased the risk of headache even more (8.5:1). CONCLUSIONS: Posterior crossbite and overbite > or =5 mm were associated with significantly increased risk of headache in children and adolescents.

Leveling the curve of Spee with a continuous archwire technique: a long term cephalometric study.

INTRODUCTION: The orthodontic technique favored by a clinician frequently determines how a deep curve of Spee (COS) is leveled. The primary purpose of this investigation was to confirm radiographically the long-term effectiveness of a continuous archwire technique--the Alexander discipline--in leveling the COS in patients with Class II Division 1 deep-bite malocclusions treated without extractions. METHODS: The sample for this retrospective cephalometric study consisted of the randomly selected orthodontic records of 31 subjects (22 female, 9 male) treated with the continuous archwire technique in the private practice of Dr R.G. "Wick" Alexander in Arlington, Texas. RESULTS: The mean pretreatment COS for this sample was 2.47 mm, and the corresponding mean posttreatment COS was 0.19 mm. The COS was completely level in 21 patients after treatment, and the rest had slight residual COS at the end of this phase. Ten of the 31 subjects remained level from 5 to 25 years after orthodontic treatment. CONCLUSIONS: The results indicate that most leveling was accomplished by the extrusion of the premolars. The continuous archwire technique is effective in leveling the COS in patients with Class II Division 1 deep-bite malocclusions treated without extractions when the initial COS is 2 to 4 mm. The leveling of the COS with the continuous archwire technique takes place by a combination of premolar extrusion and, to a lesser extent, incisor intrusion.

Alveolar bone osteoblast differentiation and Runx2/Cbfa1 expression.

Alveolar bone cells have a unique origin and functionality, but may resemble skeletal osteoblasts. Osteoblast differentiation and gene expression are regulated by the Runx2/Cbfa1 transcription factor. However, most studies on Runx2/Cbfa1 expression have been on rodent cells and the few studies on human osteoblasts have had differing results. The purpose of this study was to characterize Runx2/Cbfa1 expression in primary cell cultures derived from human alveolar bone. An alveolar bone chip was incubated in alpha-minimum essential medium (alpha-MEM) supplemented with fetal calf serum (10% FCS). Explant cultures were harvested after 3-4 weeks of outgrowth and grown in alpha-MEM with FCS. This media was supplemented with ascorbate, beta-glycerophosphate and dexamethasone to promote osteoblast differentiation over 14 days. RT-PCR analysis and Western blots showed a rapid increase in Runx2/Cbfa1 mRNA (2.1-fold) and protein (2.3-fold) levels in 3 days, followed by a slight decline. There was also a rapid increase in bone sialoprotein expression (2.9-fold) in 3 days, followed by a further increase (3.6-fold) at 14 days. There was a slower increase in alkaline phosphatase expression (1.6-fold) and activity (3.1-fold) over 7 days, followed by a gradual decline. In contrast, collagen mRNA levels showed little change over 14 days. These findings attest to the osteogenic potential of primary cell cultures derived from human alveolar bone. Osteoblastic differentiation in human alveolar bone involves an increase in Runx2/Cbfa1 expression that may be an important component of the differentiation process.

Prediction accuracy of computer-assisted surgical visual treatment objectives as compared with conventional visual treatment objectives.

PURPOSE: This present study used the conventional visualized treatment objectives (VTOs) as a tool to evaluate the predictive value of the Dolphin computer-assisted VTOs. MATERIALS AND METHODS: Presurgical cephalometric tracing predictions generated by oral and maxillofacial surgeons and the Dolphin Imaging software were compared with the postsurgical outcome as seen on lateral cephalometric tracings. Sixteen measurements of the predicted and actual postsurgical hard tissue landmarks were compared statistically. RESULTS: A paired Student's t test showed that 7 measurements had statistically significant differences for the conventional VTOs (facial angle, P < .0001; AOC, P < .0001; SNB, P = .003; ANB, P = .004; U1-NA-degrees, P = .01; U1-NA-mm, P = .02; and N perp Pog, P < .0001), while 9 measurements were statistically significant ( P = <.0001) for Dolphin (facial angle, P = .0001; AOC, P = .005; SNB, P = .001; ANB, I = .04; U1-NA-degrees, P = .003; PogNB, P = .04; U1-NA-mm, P = .002; N perp Pog, P = .0001; UFH, P = .03; and LFH, P = .03). CONCLUSION: From these data, it appears that both VTOs demonstrated good predictive comparative outcome and are equally precise.

The effects of computer-aided anteroposterior maxillary incisor movement on ratings of facial attractiveness.

BACKGROUND: Before planning orthodontic treatment, it is necessary to understand societal preferences for facial esthetics. The anteroposterior (AP) position of the maxillary incisors affects the appearance of the soft tissue profile and can be manipulated by orthodontic techniques. To improve the ability to predict the most suitable maxillary incisor position, numerous cephalometric and profilometric measurements have been suggested. Among them are the Six Elements to Orofacial Harmony proposed by L. F. Andrews, whereby forehead angulation is used to dictate maxillary incisor sagittal position. Our aim was to evaluate differences in preference for the AP position of the maxillary incisor between orthodontic and lay panels. METHODS: A smiling profile photograph was taken of a female subject who best fit the chosen soft tissue normative values and whose maxillary incisors were in an Element II position. The photograph was manipulated to simulate maxillary protrusion and retrusion at 1-mm increments to a maximum of +/-4 mm. Panels of orthodontists and nonorthodontists scored the attractiveness of the photographic variations according to a 100-mm visual analogue scale. RESULTS: The 4-mm retrusive photograph was significantly less desirable than all others, which suggests that, from an esthetic standpoint, it is preferable to either leave a normally protrusive maxillary dentition where it is or advance rather than retract the maxillary anterior teeth. Orthodontic training did not significantly affect the magnitude of the ratings or pattern of preference in our sample. CONCLUSIONS: Andrews' Element II provides an additional useful method to evaluate attractiveness relative to the maxillary incisor position.