The effects of in vitro fluoride mouth rinse on the antibacterial properties of orthodontic cements

OBJECTIVES

To investigate the ability of orthodontic cements to regain their antibacterial effect after aging for 1 month, followed by 2 weeks of fluoride 'recharging' through daily fluoride rinse.

MATERIALS AND METHODS

Four orthodontic cements were tested: composite resin-based materials (Transbond XT and Transbond Plus), a conventional glass ionomer cement (CX Plus) and dual-cured resin-reinforced glass ionomer cement (Fuji ORTHO LC) by direct contact test. After polymerization and a 30-day aging process, the samples were rinsed daily with 0.05% NaF solution for 14 days. Twenty-four hours after the last fluoride rinse, Streptococcus mutans cells (approximately 1 x 10(6) ) were placed on the surface of each sample for 1 h at 37°C to establish direct contact. Bacterial growth was monitored for 24 h by temperature-controlled spectrophotometry. Similar experiments were conducted after aging for 48 h and 72 h after the last fluoride rinse. One-way anova, two-way anova, and Tukey's multiple comparison test were applied to the data.

RESULTS

Twenty-four hours after the last fluoride rinse, the resin-modified glass ionomer and the glass ionomer showed potent antibacterial properties, whereas the composite-based material Transbond XT encouraged bacterial growth. After 72 h, only Fuji Ortho LC maintained its bacteriostatic properties while all the other tested materials showed no antibacterial activity.

CONCLUSIONS

Fourteen days daily fluoride rinse temporarily revives the antibacterial properties of the resin-modified glass ionomer cement and glass-ionomer-based cement.

[Is there a tendency for professional saturation in orthodontics in Israel?]

OBJECTIVES

The purpose of the present study is to evaluate the demand for orthodontic treatment in Israeli society, and determine the adequacy of the profession to provide service. In addition, a database of Israeli orthodontic specialist demographics will be compiled.

METHODS

There is no statistical information available as to the orthodontic treatment needs and demands in Israel. Furthermore, no survey exists measuring response to orthodontics by the Israeli patient population (i.e. attitudes, treatment time etc). In order to gauge these parameters, a written questionnaire was distributed to all the orthodontists in Israel (specialists, post graduate students and dentists who have completed their orthodontic training but have not yet earned specialist certification). The survey contained questions regarding work hours (full or partial time), the numbers of orthodontic care facilities and the distance travelled to each office, the orthodontist's claim of "free time", and whether there is a desire to increase the time spent treating patients.

RESULTS

A total of 89 orthodontists complied with the conditions of the study. Sixty nine (77.5%) were male, and 65 (73%) of them were certified specialists. It was found that 9% of the responding orthodontists practiced general dentistry in addition to orthodontics during at least 25% of their clinic time. A majority of the orthodontists (60/89) work in more than one office and 27% work in four or more different offices. About a quarter (25.8%) of the responding orthodontists report having less work than they desire and 16.9% of the orthodontists would like to work 10 or more additional hours per week. The majority of the orthodontists (80.9%) live in the central part of Israel and they travel long distances to work. Almost half of the offices (47.6%) are located 30 km or more away from their homes.

CONCLUSIONS

The present survey indicates that the demographics within the orthodontic specialty tend towards that of professional over-supply (saturation). It was also found that the majority of the orthodontists live in the central region of Israel, therefore, travelling to satellite offices is inherently time consuming.

Posterior and anterior components of force during bite loading

Late anterior crowding of teeth has been associated with the anterior component of force (ACF) developed during biting. Possible physiologic mechanisms countering ACF, including the presence of a posterior component of force (PCF), are hypothesized. In this self-controlled study, 60 subjects aged 27.05+/-3.9 years were examined for ACF and PCF that were calculated as the change in tightness of a mandibular dental contact points from non-biting to biting state. Both ACF and PCF were found to develop simultaneously. However, the PCF was 4-7 folds smaller than the ACF (p<0.001). The ACF progressively declined by 10-20 folds (p<0.001) from the posterior to anterior dentition. The lateral incisor-canine contact point had the greatest ACF decline (63-74%). ACF effect on the anterior dentition is counteracted by a protective mechanism consisted of PCF, progressive dissipation of ACF, and canine blockage.

An assessment of skeletal and dental responses to the functional magnetic system (FMS)

Correction of a skeletal Class II malocclusion with functional appliances has been accepted as a viable treatment modality. However, its mechanism of action is still disputed. This retrospective study compared 20 Class II patients treated with the functional magnetic system (FMS) with Class I and Class II groups (the control groups) of 20 untreated subjects each. Dental and skeletal changes were compared using serial lateral cephalograms. The FMS group differed significantly from the control groups in 15 of 24 parameters. The great increase in articulare-gnathion distance (3.07 mm) attributed to the attractive magnetic component of the FMS dictates a prolonged propulsion of the mandible. The skeletal:dental response ratio was 1:2 for the anterior region and 1:1 for the posterior region. The dental and skeletal parameters demonstrated a synergistic response in the maxilla and a competitive response in the mandible. This means that greater maxillary molar distal movement and incisor retroclination resulted in a more significant restraint of point A. In contrast, increasing the mandibular molar mesial movement and the incisor proclination accompanied less advancement of the pogonion. Although the skeletal contribution to the resolution of the malocclusion was less than the dental contribution (anteriorly, one third), the functional correction response was found to be regulated by skeletal factors.

The etiology of palatal displacement of maxillary canines

OBJECTIVES

To test the hypothesis that palatal displacement of the maxillary canine is completely under genetic influence.

DESIGN

A randomized controlled design studied cases affected by a severe expression of lateral incisor anomaly on one side and by milder expression of the same anomaly on the other. Comparison of frequency of occurrence of unilateral palatally displaced canine measured in each. Each side acted as control for the other within the same individual.

SETTING AND SAMPLE POPULATION

The Departments of Orthodontics of the Universities of Jerusalem and Tel Aviv and in private practice. From approximately 12,000 consecutively treated patients, all those exhibiting an anterior maxilla with a missing lateral incisor on one side, a peg-shaped or reduced lateral incisor on the other, and a palatally displaced canine (n = 19).

OUTCOME MEASURE

Missing lateral incisors, peg-shaped, and reduced lateral incisors (all genetically determined characters) have been shown to be associated with palatal displacement of the canine. The canine displacement is presumed by some authorities to be similarly genetically determined. If this is so, then the impacted canine should occur with equal frequency on either side in the patient with a missing lateral incisor on one side and a peg-shaped or reduced lateral incisor on the other.

RESULTS

The canine aberration occurred far more frequently on the side of the diminutive lateral incisor.

CONCLUSION

There is an environmental factor involved in the palatal displacement of maxillary canines.

Attachment bonding to impacted teeth at the time of surgical exposure

This study examines the relative success of bonding an attachment to an impacted tooth at the time of surgical exposure, compared with placing it on a subsequent occasion. In addition, the relative merits of various attachments, the choice of bonding site and whether or not pumice prophylaxis is necessary, were tested. The results showed that bonding at the time of exposure is superior to its performance at a later date, that the use of an eyelet attachment has a lower failure rate than the use of a conventional bracket, that the palatal aspect offers the poorest bonding surface and that pumicing the exposed tooth offers no advantage over immediate etching of the exposed enamel. The results of this study refute the view that the circumstances prevalent at the time of surgical exposure are not conducive to the reliable bonding of an attachment to an impacted tooth.