Centrographic analysis of 1-phase versus 2-phase treatment for Class II malocclusion.

INTRODUCTION: Cephalometric analyses have been used by orthodontists to track growth and monitor treatment effects. Most of these analyses have normative values to which patients are compared, but some "normal" patients vary quite a bit from the normative values. The centrographic analysis is a visual analysis with no angles to measure or normative values to compare. After a reference plane is developed, the relative position of variable landmarks can be seen. METHODS: We used the centroid centrographic analysis to study the effects of 1-phase and 2-phase orthodontic treatment. Phase 1 treatment consisted of bionator (n = 66), headgear/biteplane (n = 69), or observation (n = 65) until a Class I molar relationship was achieved or 2 years had elapsed. After 1 year, all subjects underwent full orthodontic treatment with fixed appliances. RESULTS: Centrographic analysis showed that early treatment has effects on the mandible. However, the differences were not apparent by the end of fixed appliance treatment. CONCLUSIONS: The skeletal effects of phase 1 treatment disappear by the end of fixed appliance treatment.     

One-phase vs 2-phase treatment for developing Class III malocclusion: A comparison of identical twins

Despite the known influence of early treatment on the facial appearance of growing patients with skeletal Class III malocclusion, few comparative reports on the long-term effects of different treatment regimens (1-phase vs 2-phase treatment) have been published. Uncertainty remains regarding the effects of early intervention on jaw growth and its effectiveness and efficiency in the long term. In this case report, we compared the effects of early orthodontic intervention as the first phase of a 2-phase treatment vs 1-phase fixed appliance treatment in identical twins over a period of 11 years. Facial and dental changes were recorded, and cephalometric superimpositions were made at 4 time points. In spite of the different treatment approaches, both patients showed identical dentofacial characteristics in the retention phase. Through this case report, we intended to clarify the benefits of undergoing 1-phase treatment against 2-phase treatment protocols for treating growing skeletal Class III patients.     

External apical root resorption in Class II malocclusion: a retrospective review of 1- versus 2-phase treatment.

External apical root resorption (EARR) is an imperfectly understood problem of orthodontic treatment. The records of 138 children with Class II malocclusion (overjet > 7 mm) participating in a randomized clinical trial of early orthodontic treatment were reviewed. The patients were treated in either 1 phase with fixed appliances only (n = 49) or 2 phases with headgear (n = 49) or bionator (n = 40) followed by fixed appliances. The 3 groups were similar in age, sex, and malocclusion severity at enrollment. The records examined included anamnestic data, clinical examination records, panoramic radiographs before and after fixed appliance therapy, and posttreatment periapical radiographs. All radiographs were reviewed and scored independently by 2 examiners for maxillary incisor root development, morphology, and EARR. Of the 532 incisors scored, 11% of central and 14% of lateral incisors demonstrated moderate to severe (>2 mm) EARR. The proportion of incisors with moderate to severe EARR was slightly greater in the 1-phase treatment group. There was no difference in the incidence of EARR between teeth that had had trauma and those that had not, and there was only a slight increase in frequency of root resorption in teeth with unusual root morphology. Significant associations exist among EARR, the magnitude of overjet reduction, and the time spent wearing fixed appliances. However, not all incisors in a child respond in the same way, so other variables must play a role in determining the root response to orthodontic forces.     

Comparison of peer assessment ratings (PAR) from 1-phase and 2-phase treatment protocols for Class II malocclusions.

The purpose of this study was to compare the dentoalveolar outcomes after 1-phase and 2-phase orthodontic treatment of Class II malocclusions. Class II subjects (n = 208) were randomized to 1-phase or 2-phase treatment with either bionator or headgear/biteplate. The peer assessment rating (PAR) was calculated from pretreatment, prephase 2, and final study models. Chi-square, Kruskal-Wallis, and Wilcoxon rank sum tests were used to evaluate the differences among treatment groups, sexes, races, pretreatment, mandibular plane angle, severity, and compliance. Spearman rank correlation coefficients were used to examine relationships between PAR at different times. The dropout rate of 24.6% did not adversely affect the ability to detect differences of clinical importance or impact treatment groups disproportionately. There were no significant differences with respect to initial PAR or final PAR among the 3 treatment protocols. The 2 early treatment groups had lower PAR scores than the 1-phase group before phase 2 (P =.0001). Lower PAR scores were achieved at both the beginning and end of phase 2 in girls (P =.03; P =.02, respectively). There were differences in the pre-phase-2 and post-phase-2 PAR scores based on initial severity (P =.0006; P =.02, respectively), with greater improvement in the patients whose malocclusions were less severe initially. Mandibular plane angle had no effect on pre-phase-2 or post-phase-2 PAR scores. These results do not support the hypothesis that different dentoalveolar outcomes are obtained between 2-phase and 1-phase treatment of Class II malocclusions.     

Outcomes in a 2-phase randomized clinical trial of early class II treatment

In a 2-phased, parallel, randomized trial of early (preadolescent) versus later (adolescent) treatment for children with severe (>7 mm overjet) Class II malocclusions who initially were developmentally at least a year before their peak pubertal growth, favorable growth changes were observed in about 75% of those receiving early treatment with either a headgear or a functional appliance. After a second phase of fixed appliance treatment for both the previously treated children and the untreated controls, however, early treatment had little effect on the subsequent treatment outcomes measured as skeletal change, alignment, and occlusion of the teeth, or length and complexity of treatment. The differences created between the treated children and untreated control group by phase 1 treatment before adolescence disappeared when both groups received comprehensive fixed appliance treatment during adolescence. This suggests that 2-phase treatment started before adolescence in the mixed dentition might be no more clinically effective than 1-phase treatment started during adolescence in the early permanent dentition. Early treatment also appears to be less efficient, in that it produced no reduction in the average time a child is in fixed appliances during a second stage of treatment, and it did not decrease the proportion of complex treatments involving extractions or orthognathic surgery.     

双期矫治与摆式矫治器治疗安氏Ⅱ类错(牙合)牙根吸收对比研究

目的：对比研究双期矫治和摆式矫治器在治疗安氏Ⅱ类错[牙合]时的牙根吸收情况。方法：选取双期矫治病例18例,摆式矫治器病例20例,治疗前均无牙根吸收,治疗前后拍摄上切牙X线根尖片,在根尖片上对治疗组的上切牙牙根吸收评级,对比分析两治疗组病例的牙根吸收情况。结果：中切牙和侧切牙在两治疗组中的根吸收程度无统计学差别,但是无论双期矫治还是摆式矫治器矫治,侧切牙的根吸收程度都比中切牙严重。结论：在治疗安氏Ⅱ类错[牙合]时,双期矫治和摆式矫治器矫治的牙根吸收程度基本相同。     

Severe mandibular retrognathism: orthodontic versus surgical orthodontic treatment.

1. Treatment of Class II, Division 1 malocclusions should be accomplished by normalization of the abnormal structures that are identified diagnostically. 2. In the presence of mandibular retrognathism and unfavorable growth potential (limited amount, undesirable direction), surgical mandibular lengthening should be incorporated into the treatment plan. 3. Compensation for mandibular retrognathism by conventional orthodontic and facial orthopedic treatment incurs the risk of (a) increase in nasolabial angle, (b) reduction in upper lip support, (c) increase in lower facial concavity, (d) excessive proclination of lower incisors with compromise of labial periodontal support, and (e) protracted duration of appliance therapy and accompanying detrimental periodontal and root resorption effects.     

Creep versus microstructure of gamma2-containing amalgams.

An analysis of the relationship between creep and microstructural characteristics of several gamma2-containing amalgams showed the grain size of the Ag-Hg phase (gamma1) to be a predominant factor influencing creep. When gamma1 grain size is increased, creep is reduced.     

Outcomes of open versus closed treatment of mandibular subcondylar fractures.

OBJECTIVES: The purpose of this study was to compare the long-term treatment results of open reduction and rigid internal fixation (ORIF) with closed reduction and maxillomandibular fixation (CRMMF) for subcondylar fractures when guided by specific indications and contraindications. PATIENTS AND METHODS: A protocol for the treatment of condylar process fractures was developed that included absolute and relative indications and contraindications as well as a technique regimen. To evaluate the results of this protocol, 10 patients treated with CRMMF and 10 treated by ORIF were recalled after a minimum of 6 months and examined for gender, race, diagnosis, age at injury, time since operation, and cause of the fracture. Each group was assessed by 2 blinded investigators for maximum interincisal opening, right lateral excursion, left lateral excursion, protrusive movement, deviation on opening, scar perception, motor function, sensory perception, contour perception, occlusion, and perception of pain. Nonparametric data were compared for statistical significance with a chi-square analysis and parametric data with an independent samples t-test (P < .05). RESULTS: No statistically significant differences existed between the ORIF and CRMMF groups for gender, race, diagnosis, or cause. Moreover, no differences existed for age at injury, maximum interincisal opening, right lateral excursion, left lateral excursion, protrusive movement, deviation on opening, or occlusion. Differences were noted between groups for time since operation, scar perception, and perception of pain. Using the protocol outlined, there were no differences between the ORIF and CRMMF groups for ranges of motion, occlusion, contour, and motor or sensory function. The ORIF group was associated with perceptible scars. The CRMMF group was associated with chronic pain. CONCLUSIONS: Using a treatment protocol, there were few differences in outcomes between patients treated with CRMMF and ORIF for subcondylar fractures.     

Appointment frequency versus treatment time

A study is presented of 92 orthodontic patients whose treatment was completed between the years 1985 and 1987. Because of the unique situation in the clinic in which the study was undertaken, patients are seen at long intervals as compared to what normally would be considered the "standard" length of time between appointments. It is concluded that the overall length of treatment did not increase significantly, even though patients were seen much less frequently. The differences may have been partially attributable to the new high-tech appliances and materials used today and partially related to the fact that indeed it may not be necessary to see patients at 3- or 4-week intervals.