What's New in Dentistry

Prophylactic antibiotics recommended before orthognathic surgery. Some orthodontic patients require orthognathic surgery as part of their treatment plan. However, with any intraoral surgery, there is the risk for infection. Some surgeons prescribe antibiotics after surgery if an infection develops. Other surgeons recommend prophylactic antibiotics to reduce the risk of infection. Is there any evidence that prophylactic antibiotics are beneficial before orthognathic surgery? A study published in the Journal of Oral and Maxillofacial Surgery (1999;57:1403–1406) evaluated the effect of prophylactic antibiotics on the incidence of infection after orthognathic surgery. This was a randomized, double-blind, placebo-controlled clinical study. The sample consisted of 50 participants who had various osteotomies. Before surgery, the subjects were given penicillin, cephalosporin, or a placebo. Then the incidence of infection in the participants was observed after surgery. The results showed that the incidence of infection in the participants receiving either of the 2 antibiotics was between 10% and 15%. However, in the placebo group, the incidence of infection was more than 50%. In conclusion, although the prophylactic antibiotics did not eliminate the possibility of infection, it reduced the likelihood of infection by 30% to 40% after orthognathic surgery.

Only a fraction of temporomandibular disorders are due to occlusal problems. The relationship between malocclusion and temporomandibular disorders is controversial. Some clinicians believe that occlusal disharmony causes dysfunction of the temporomandibular joint (TMJ). However, there is little evidence to confirm this association. A study published in the Journal of Prosthetic Dentistry (2000;83:66–75) evaluated the predictive value of specific occlusal variables for producing temporomandibular disorders. The sample consisted of 350 individuals who had intracapsular temporomandibular disorders. They were differentiated into 2 groups: those with disk displacement and those with osteoarthrosis with inflammation of the joint. Then these samples were compared with asymptomatic controls. In evaluating the samples, these authors also tried to correlate occlusal variables such as overjet, overbite, open bite, posterior crossbite, and centric slides with the incidence of intracapsular disorders. On the basis of careful analysis of all of the variables, the authors found that the predictive value of malocclusion for temporomandibular disorders was somewhere between 5% and 27%. Therefore, 73% to 95% of the time, other nonocclusal factors are necessary to explain disorders of the TMJ.

Anterior disk displacement causes mandibular growth asymmetries. Anterior disk displacement is a common intracapsular disorder in adults. Although a displaced disk may cause popping and locking of an adult TMJ, what problems are produced when disk displacement occurs during childhood or adolescence? This question was addressed in a study that was published in Acta Odontologica Scandinavica (1999;57:290–300). The sample consisted of 21 rabbits that were divided into 3 groups. In the first group, the meniscus or disk was surgically displaced anteriorly. In another group, the area was opened, but the disk was not displaced. Finally, in a third group, no surgery was performed on the animals. The animals were all young and growing. After a 3-month experimental period, while the animals continued to grow, the ramus, condyle, and associated structures were evaluated both macroscopically and microscopically to determine the changes that occurred. The results showed that a significant asymmetry developed; there were alterations in condylar growth on the affected side. Histologic evaluation showed that no osteoarthrosis was present. These condyles simply underwent an alteration in the growth process and grew less than the nonaffected side. In conclusion, anterior disk displacement causes growth asymmetry in young experimental animals.

Prostaglandin confirms inflammation of the TMJ. Some patients with temporomandibular disorders have significant pain in their joints. In some of these situations, the pain is due to inflammation of the synovial membrane, and in others, the pain may have a different cause. It would be beneficial for clinicians treating a pain patient to be aware of the etiology of the disorder. A study published in the Journal of Oral and Maxillofacial Surgery (2000;58:180–186) evaluated the synovial fluid for the presence of prostaglandin 2 in a group of symptomatic and asymptomatic participants. The sample consisted of 24 patients with inflammatory joint disease. They were compared to 4 control subjects. The degree of joint pain during opening and closing was evaluated. In addition, the synovial fluid was sampled to determine the level of prostaglandin 2 in the joint. The results show that prostaglandin 2 was not detected in the synovial fluid of normal joints. However, in 67% of the patients with inflammatory joint disease, the prostaglandin 2 levels were significantly elevated and correlated positively in the pain patients. In the future, prostaglandin 2 levels may be a method of detecting early evidence of inflammatory joint disease.

Peri-implantitis defects are reversible with bone grafting. Implants are well accepted in dentistry. Many orthodontic patients have had congenitally missing teeth restored with implants. The success rate of single-tooth implants is more than 90%. However, occasionally implants may fail because of peri-implantitis and bone loss around the implant. A study published in the International Journal of Oral and Maxillofacial Implants (2000;15:125–138) evaluated a method of resurrecting failing implants. The sample consisted of 25 participants with single-tooth implants that were failing because of peri-implantitis. All of these implants had lost at least 5 mm of bone adjacent to the implant. In order to reverse the bone loss, the authors elevated a flap around the implant and removed the granulation tissue in the area of the bone defect. Then they cleaned the implant surface with an air-powder abrasive instrument and placed a bone graft that was harvested from either the chin or the ramus of the mandible. The implants were evaluated up to 3 years later. Only 2 of the 25 bone graft procedures were unsuccessful. This is a success rate of more than 90%. When the authors evaluated the implants radiographically, the vertical and horizontal bone defects were generally eliminated and within 1 to 2 mm of their original height. In conclusion, bone grafting is a successful method for salvaging implants that are failing because of peri-implantitis.