Journal of Orthodontics

To determine if the extractions of lower primary canines are an effective procedure to relieve crowding of the labial segment.

randomized controlled trial.

83 cases were collected in clinics in Italy, Germany and Wales. The groups were followed over a 2-year period.

Subjects were randomly allocated to a primary canine non-extraction or extraction group. Dental casts of the patients were collected at the start and at the recall period of the trial. The outcome measures recorded were lower incisor crowding, arch length, intermolar width, overbite, overjet, lower clinical crown heights and lower incisor inclinations.

The Mann–Whitney test was used to compare the differences between the extraction and non-extraction groups.

In both groups, crowding reduced 1.27 mm in the non-extraction group and 6.03 mm in the extraction group. The difference between the 2 groups was 4.76 mm (P<0.05). The arch perimeter decreased more in the extraction group by 2.73 mm (P<0.05). As the incisor inclination stayed essentially the same, the loss in arch length was attributed to the molars moving forward. The net gain from extracting deciduous canines was 2.03 mm.

There was a reduction in lower incisor crowding as a result of lower primary canine extraction. However, arch perimeter decreased more in the extraction group leaving less space for the eruption of the lower secondary canines.

Non-apneic snoring is a very common problem, which impacts on all family members. Oral appliances have been used in the management of snoring. These posture the mandible forward during sleep, opening the airway and so reducing the potential for noise generation. This articles aims to objectively evaluate the effectiveness of mandibular advancement splints (MAS) in non-apneic snorers.

Prospective clinical trial.

University Dental Hospital and School.

35 consecutively referred adults with proven non-apneic snoring.

Subjects were fitted with a removable, adjustable Herbst MAS.

Questionnaires determined changes in snoring incidence, daytime tiredness, any side effects and their duration. Eleven subjects completed overnight domiciliary sleep recordings of oxygen saturations, pulse rates and sound profile, before and 1 month after fitting the MAS.

The questionnaires and sleep recordings suggested that the MAS significantly reduced snoring incidence (p<0.05) and improved sleep quality. Daytime tiredness, as assessed by the Epworth Sleepiness Scale, was significantly reduced (p<0.001). Initial side effects of muscular and TMJ discomforts were mostly resolved after 1 month of appliance wear.

Use of a MAS improves snoring incidence and sleep quality in most patients with non-apneic snoring.

To evaluate the radiographic changes that occur in the pharynx and surrounding structures with alteration of posture from the upright to the supine position and the effect that mandibular protrusion whilst supine has on these dimensions.

Prospective cephalometric study.

University Dental Hospital and School.

This prospective study involved 35 consecutively referred adults with proven non-apneic snoring. Lateral skull radiographs were obtained with the subjects upright in occlusion, supine in occlusion and supine with the mandible protruded to the maximum comfortable position. Radiographs were traced and digitized, and the pharyngeal dimensional changes and hyoid position were examined. Males and females were examined separately.

Radiographic pharyngeal dimensions were changed with altered posture, resulting in significant reductions in the minimum post-palatal (p<0.01) and post-lingual (p<0.05) airway measurements in the supine position. Mandibular protrusion whilst in the supine position produced increases in the functioning space for the tongue.

A supine posture results in significant reductions in pharyngeal airway measurements of non-apneic snorers. Mandibular protrusion whilst in the supine position produces an increase in the functioning space for the tongue.

To determine the accuracy of direct or indirect bracket placement.

A prospective, randomized comparison of 2 different methods of bracket placement.

Queens Hospital, Burton upon Trent, UK between February and May 2001.

Twenty-six consecutive patients requiring upper and lower MBT™ pre-adjusted Edgewise appliances had their labial segments bonded directly or indirectly according to a split mouth system of allocation. Before and after bond-up all brackets were photographed and measured from tracings to determine positional differences from the ideal.

Using ANOVA (General Linear Model), vertical errors were found to be greater than those in the horizontal plane, which in turn were greater than angular errors (p<0.05). Errors were greater in the maxillary arch than in the mandibular arch. There was no significant difference between the mean errors produced by the two methods of bracket placement.

Mean bracket placement errors were similar with both techniques.

To evaluate the effects of local injection of insulin-like growth factor I (IGF-I) on the growth of mandibular condyle in mature rats.

Sixteen 15 week-old male rats were used in this study. In the experimental group, IGF-I at a concentration of 50 μg/ml was injected into articular capsules of the condyle, while rats in the control group were injected with equal volume of physiological saline. These injections were performed three times at 7 day intervals, and all of the rats were killed on the 7th day after the last injection. Tetracycline and calcein were used for vital staining. After death, the condyles were extracted and undecalcified ground sections were prepared for histological and histomorphometric observations. The thickness of the cartilaginous layer of the condyle, the percentage of bone area in the subchondral cancellous bone layer and the amount of endochondral bone growth in the condyle were measured. The significance of the difference in these measurements between IGF-I and control group was evaluated.

An increase in the thickness of the cartilaginous layer, and a decrease in the percentage of bone area in the subchondral cancellous bone layer was recognized in IGF-I treated condyle. The amount of endochondral bone growth in the experimental group was greater than that in the control group.

The local injection of IGF-I into mature condyle seemed to reactivate the process of endochondral bone formation and induced actual bone growth in mature condyle.