Posttreatment changes after successful correction of Class II malocclusions with the twin block appliance.

This investigation is a continuation of a previously published study assessing the treatment effects of the Twin Block appliance. All active treatment was carried out during the mixed dentition stage (mean starting age, 9 years 1 month) with final follow-up for the treatment group occurring in the permanent dentition (mean age, 13 years 1 month). Of the original group consisting of 28 consecutively treated severe skeletal Class II patients, 26 were available for follow-up. A comparison group of 28 untreated Class II subjects matched for age, sex, and vertical facial type was obtained from the Burlington Growth Centre according to the original study design. Of these 28 control subjects, 24 had 4-year follow-up cephalometric films available. The mean age of the controls was 12 years 11 months at the time of follow-up. During the active treatment phase, the Twin Block group experienced an average increase in mandibular unit length of 6.5 mm over a mean of 14 months (annualized rate of change of 5.6 mm per year). In comparison, the control group experienced a 2.3 mm increase in mandibular unit length during the 13-month observation period (annualized rate of 2.1 mm per year). In the posttreatment phase, the change in mandibular unit length for the Twin Block group was 6.0 mm over a 36-month period (annualized rate of change of 2.0 mm per year). The control group experienced an average increase in mandibular unit length of 6.7 mm over the posttreatment assessment period that was 34 months in duration (annualized rate of change of 2.4 mm per year). Although there was a slight reduction in mandibular growth rate after treatment, much of the significant increase in mandibular length achieved during the active phase of treatment with the Twin Block appliance was still present 3 years later when the subjects had matured into the permanent dentition stage.

Treatment effects of the twin block appliance: a cephalometric study.

A clinical study was undertaken to investigate the treatment effects of a modified Twin Block appliance. Pretreatment and posttreatment cephalometric records of 28 consecutively treated patients with Class II malocclusions were evaluated and compared with an age- and sex-matched sample of untreated Class II control subjects. The treatment group was considered to have severe skeletal Class II malocclusions and was treated using only the Twin Block appliance. Results indicated that mandibular growth in the treatment group was on average 4.2 mm greater than in the control group over the 14-month treatment period. In addition, some dentoalveolar effects in both arches contributed to the overjet correction. No statistically significant increase in the SN-mandibular plane angle occurred during treatment and, in general, the magnitude and direction of the skeletal changes were found to be quite favorable.

Dens evaginatus: review of the literature and report of several clinical cases.

Dens evaginatus (DE) presents as an innocuous looking tubercle of enamel on the occlusal surface of a tooth, most commonly a bicuspid. Problems can arise when the tubercle is either worn, ground, or fractured off, resulting in pulpal exposure and possible loss of vitality of the tooth. Dentists who perform orthodontic treatment should be aware of this dental anomaly, which occurs in at least two per cent of the Asian and Native Indian populations. Bicuspid extraction cases should involve the extraction of the anomalous premolars rather than the normal ones. In addition, the dentist should be mindful of occlusal changes that may occur during treatment or occlusal equilibration, both of which can jeopardize the vitality of teeth with DE. Pulp capping or partial pulpotomy has been postulated to be one of the most reliable forms of vital tooth treatment when pulp exposure is encountered following the sterile removal of the tubercle. When pulp exposure is not encountered, preventive resin composite sealing of the dentin or class I amalgam cavity preparation seems to be the treatment of choice.

Case report: modified use of the Jasper Jumper appliance in a skeletal Class II mixed dentition case requiring palatal expansion.

The Jasper Jumper appliance provides a method of Class II correction with an active force component that the patient cannot remove. A modification of classic Jasper Jumper usage is illustrated in a mixed dentition case where full banding is impractical. This report shows how Jasper Jumper springs can be attached to a fixed maxillary expansion appliance and a lower lingual holding arch for correction of a Class II malocclusion. Cephalometric analysis revealed that despite seemingly adequate anchorage for the springs, treatment changes were largely dentoalveolar, with minimal improvement in the underlying skeletal structures. Some restraint of maxillary growth was found, but most of the overjet correction was due to forward movement of the mandibular dentoalveolar complex and retraction of the maxillary dentoalveolar complex.

Whole body bone resorption in the growing pig.

UNLABELLED: Our knowledge of total body bone resorption during growth is limited. The primary purpose of this study was to determine if a commercially available bone resorption assay, developed for measuring human bone resorption, could be used to measure whole body bone resorption in young, growing pigs. A secondary purpose was to evaluate if this method could detect changes in bone resorption in response to certain dental appliances which have been shown to change mandibular and maxillary growth. Five growing 4-month-old male Hanford minipigs (Sus scrofa) were housed in metabolic cages for 24 h, every other day, over a period of 1 month. Three of the animals were fitted with a mandibular protrusive orthodontic appliance. Total 24 h urines were collected in which the concentration of creatinine and collagen type I N-telopeptide crosslinks (NTx, a marker of bone resorption) were measured. The NTx immunoassay was originally developed for the analysis of human urine. Pig bone was powdered, defatted, and decalcified, and the resulting powder digested with bacterial collagenase. The digest was screened for NTx content, in the same fashion as the pig urines. Bone extract and pig urines were cross-calibrated to a standard of adolescent human urine. This allowed calculation of the daily quantity of pig bone resorbed. Daily metabolite excretion was quite variable in these growing animals; for NTx the CV was 31%, for creatinine the CV was 25%. The mean daily quantities of bone resorption ranged between 26 and 46 grams of bone which amounted to 1.2-1.7% of estimated total skeletal mass. The protrusive appliances increased bone resorption significantly during the first two weeks of the trial. IN CONCLUSION: the NTx assay can be used to measure bone resorption in pigs; the assay is sensitive enough to indicate changes in bone resorption, such as those caused by an orthodontic mandibular protrusive appliance. During growth, bone resorption varies greatly from day to day. On average, every 24 h, 1.4% of the skeletal mass is resorbed.

Dens evaginatus from an orthodontic perspective: report of several clinical cases and review of the literature.

The anomaly of dens evaginatus manifests itself as an innocuous-looking tubercle of enamel on the occlusal surface of a premolar tooth. Problems can arise when the tubercle is either worn, ground, or fractured off, resulting in pulpal exposure and possible loss of vitality of the tooth. Orthodontists should be particularly aware of this dental anomaly, which occurs in at least 2% of the Asian and Native Indian population. Premolar extraction cases should be planned to include extraction of the anomalous premolars instead of the normal ones. In addition, the orthodontist should be wary of occlusal changes during treatment or occlusal equilibration that might jeopardize the vitality of teeth with dens evaginatus. Pulp-capping or partial pulpotomy has been postulated as the most reliable form of treatment to prevent loss of vitality of the affected teeth and to allow continued root maturation where necessary.

State family leave laws and the legal questions they raise.

Some lawmakers proclaim that their vote for family leave laws is a vote for the American family. This author surveys these popular laws state by state and discovers disturbing legal questions in this new front of costs and obligations that is advancing on employers.

The new wave of employee benefits litigation.

Forecasters warn of storm clouds on the horizon in the form of increased benefits litigation for employers. The threat is real, but taking precautions now can reduce the risk.