American journal of orthodontics最新文献

Prostaglandins (PGs) have been suggested as mediators of bone resorption. In addition, their presence in the periodontal tissues has also been demonstrated. To characterize the involvement of PGs in orthodontic tooth movement, indomethacin, an aspirin-like drug and a potent inhibitor of PG synthesis, was administered orally to six mongrel cats; another group of six animals served as controls. These animals were fitted with orthodontic appliances that consisted of coil springs stretching between the right side maxillary and mandibular canines and third premolars. The data for tooth-movement measurements were analyzed by repeated measures factorial analysis of variance. At the end of the 21-day experimental period, the rate of tooth movement in experimental animals was approximately one half of controls (P < 0.01). Findings of this study imply a significant role for PGs in bone resorption during orthodontic therapy. It is recommended that aspirin-like drugs not be administered to patients undergoing orthodontic tooth movement as it may extend the treatment time.

A problem that has limited orthodontic treatment is lack of buccal-lingual alveolar width into which teeth can be moved. Causes may range from surgical obliteration to physiologic constriction after tooth removal. Lack of buccal-lingual alveolar width does not have to be an orthodontic limitation anymore. A technique used routinely to graft alveolar clefts can remedy this problem. Autogenous cancellous bone is placed subperiosteally on the buccal aspect of the constricted edentulous space. The flap is closed over the bone. The adjacent teeth may be orthodontically moved into the grafted edentulous area in approximately 6 weeks. Long-term follow-up has revealed excellent orthodontic stability, periodontal health, and dental vitality. A case report of one patient with loss of buccallingual alveolar space is presented. It is concluded that loss or lack of sufficient buccal-lingual alveolar width no longer must be an orthodontic limiting factor.

In today's orthodontic practice, disease control must undergo major reevaluation and restructuring. The knowledge of the natural history and treatment of many highly transmissible diseases to which orthodontic personnel are at high risk is changing rapidly. Among these diseases are acquired immune deficiency syndrome (AIDS), hepatitis B virus, and the herpesvirus complex (currently five types). If barrier techniques are not in place, it is possible to cross-infect orthodontic personnel and patients alike. Clinical orthodontics, with its higher volume of patients (on a daily basis) than other dental practices, requires a custom-made sterilization schema tailored to each office. Proper organization of instruments to permit orderly processing, storing, and use is even more important than before. Turnaround time of processing instruments, corrosion control, and minimizing of dulling of cutting edges are critical. Treatment of surfaces and chair/unit facilities with improved disinfection techniques is a necessity. Protection of hands and eyes by appropriate means is discussed with practical guidelines for the use of gloves by chairside personnel. Many fomites (inanimate disease transmitters) lurk in the orthodontic office and must be eliminated. Finally, the most important ingredient to any change—the orthodontic office staff—must be enlightened, trained, and supervised by the orthodontist to effectively and efficiently switch from the old to the new.

The prevalence of enamel decalcification beneath orthodontic bands has indicated the need for a fluoride-releasing, enamel-adhesive orthodontic luting cement. The purpose of this study was to compare the retentive bond strengths of orthodontic bands cemented with two new fluoride-releasing cements, a zinc polycarboxylate and a glass ionomer, with the retentive bond strength of bands cemented with the standard orthodontic cement zinc phosphate. The site of cement failure was also evaluated. One hundred eighty extracted human molar teeth were embedded in resin blocks and randomly assigned to three cement groups. Adapted bands were cemented by a clinically acceptable technique. The cemented teeth were then assigned to one of three time intervals-24 hours, 7 days, and 60 days-and thermocycled in synthetic saliva. The force required to initially fracture the cement bond was used as a measure of cement retention. By means of the Instron, a tensile load was applied to each cemented band. The maximum retentive strength (cement failure) was interpreted from the stress-strain curve at the point where linearity deviated. The failure site was judged subjectively: between cement and enamel, within the cement, or between cement and the band. Using stress at failure, an analysis of variance showed no significant differences among the retentive strengths of the three cements. The chi-square test revealed a significant difference (P < 0.01) between failure sites of the zinc phosphate and glass ionomer cements. Significantly more bands cemented with the glass ionomer failed at the cement/band interface, leaving the cement adhered to the tooth. Both the glass ionomer and zinc polycarboxylate cements tested were found to be suitable as orthodontic luting agents. In addition, the favorable failure site of the glass ionomer (cement adhered to enamel) may offer clinical protection against decalcification under loose bands.

A procedure is described in which lateral facial photographs were cut apart and reassembled in ways that approximated desired esthetic change. Two groups of subjects were asked to complete the Sassouni “cut-up-paste-back” procedure. Group 1 consisted of 20 adult dental professionals; group 2 comprised 18 college students unacquainted with dental studies. Both groups made similar alterations on a photograph at the beginning and at the end of a 2-week period. Photographic alterations were highly similar to written descriptions of intended changes. The “cut-up-paste-back” procedure is a simple and inexpensive way to facilitate dentist-patient communication during treatment planning. The procedure also has applicability for research in facial esthetic preference.

A case report of a Class II, Division 1 subdivision malocclusion with a deep overbite and a marked overjet is presented. The patient was a 14-year-old boy with the potential for continued growth. The lip positions imposed by the teeth and the facial skeleton increased the labioversion of the maxillary incisors. A Begg light-wire appliance was used throughout the course of treatment. Since the maxilla and mandible were retrognathic to the cranial base, the malocclusion was treated by nonextraction methods.