Choosing an implant system: facts and fallacies.

Root form implants may be either cylindrical or threaded, metal or calcium-phosphate-ceramic (CPC) coated. Biological and mechanical principles dictate a preference for threaded implants, and a retrospective study comparing surface characteristics reveals a marked preference for HA-coated threaded implants, at least in the short-term period of observation.

The surgical treatment of skeletal anterior open-bite deformities with rigid internal fixation in the mandible.

The rationale for the surgical correction of skeletal anterior open-bite deformities by bilateral mandibular rotation osteotomy is presented. Results of this procedure in which rigid internal fixation is used are reported and show a very high degree of long-term stability. The procedure offers a useful alternative to the more common approach of posterior maxillary intrusion, which does not always address the cosmetic defect.

The surgical correction of mandibular prognathism using rigid internal fixation--a report of a new technique together with its long-term stability.

A historical review of the literature for the surgical correction of mandibular prognathism is presented, together with a list of ideal conditions for the successful treatment of this condition. This is a report of a new surgical technique which satisfies the majority of these principles and demonstrates stability at the osteotomy site.

Stability of mandibular advancement osteotomy using rigid internal fixation.

Forty-three patients who underwent surgical lengthening of the mandible using an inverted L osteotomy, bone grafting, and rigid internal fixation between the mandibular segments were evaluated by retrospective cephalometric analysis for longitudinal skeletal and dental changes. Postoperative response (means = 1 year 9 months) was found to demonstrate a high level of stability with some individual variability. No propensity for relapse was observed in any postoperative time interval. Condylar repositioning postoperatively appeared to be an important factor in those patients who exhibited any relapse tendency. Overall postoperative stability of this surgical/fixation technique appears to be significantly improved compared with previously documented techniques.

Micropuncture study of the superficial nephron of Cercopithecus aethiops.

Clearance and micropuncture experiments were performed on male Cercopithecus monkeys weighing between 2 and 4 kg to evaluate the function of the superficial nephron. The mean glomerular filtration rate was 4.47 +/- 0.32 ml/min. The fraction of filtered sodium, potassium, calcium, magnesium, and phosphate remaining at the end of the accessible proximal tubule were 54 +/- 3, 64 +/- 4, 70 +/- 3, 79 +/- 5, and 39 +/- 5%, respectively. The concentration of magnesium and calcium in the tubule fluid rose significantly along the length of the proximal tubule. The tubule fluid bicarbonate concentration was measured by determination of total CO2 with microcalorimetry. The tubule fluid to blood bicarbonate ratio fell to 0.48 +/- 0.06 at the late proximal tubule collection site, as the tubule fluid to ultrafiltrable chloride concentration ratio rose to 1.08 +/- 0.02. Thus, bicarbonate is reabsorbed in preference to chloride in the superficial proximal tubule of the monkey, to provide a potential driving force for water and salt absorption. By the time the tubular fluid reached the distal tubule sampling site, most of the filtered sodium potassium, calcium, magnesium, and chloride was reabsorbed, suggesting the loop of Henle as a major site of ion reabsorption. Segments beyond the distal tubule collection site reabsorbed little of the delivered ions. These studies indicate that the function of the superficial nephron resembles that of species previously studied, except that calcium reabsorption is demonstrably diminished in the proximal convoluted tubule relative to other mammals.

Cortex-to-cortex healing after mandibular osteotomy.

Cortex-to-cortex healing is frequently attempted following orthognathic surgical procedures. This paper reports the results of in vivo experiments to investigate the healing process when two cortical surfaces are conjoined and discusses the implications in relation to the surgical correction of mandibular prognathism.

Mandibular advancement surgery: stability following a modified fixation technique.

A technique for surgical mandibular advancement is described. Short- and long-term results are monitored by cephalometric assessment and a high degree of postfixation stability is demonstrated.

Avascular necrosis of the mandibular ramus in the baboon (Papio ursinus) following orthognathic surgery.

The maintenance of an adequate blood supply to the mandible following orthognathic surgery is of extreme importance if satisfactory healing is to be achieved. With this object in mind, this study was undertaken to assess the effects of disrupting the blood supply of the baboon mandible by means of L- and C-osteotomies. Ten adolescent baboons of the species Papio ursinus were used as the experimental animals for the study. On five of them a modified vertical subsigmoid osteotomy (L-osteotomy) and on five a C-osteotomy of the mandibular ramus were performed. In each experimental animal the osteotomy was undertaken on one side of the mandible only, the other side serving as a control. After a postoperative period of 14 days the animals were killed, the entire mandible removed, and the tissues prepared for examination with the light microscope. Histometric analysis revealed a significant degree of avascular necrosis in certain areas of the proximal or condylar fragments and to a lesser extent in the distal fragment. Avascular necrosis was also seen on the control side. It was also revealed that the periosteum and attached muscles of mastication play a role in the blood supply of the mandible and that the additional attachment of the temporalis muscle to the proximal fragment is of no advantage in enhancing the vascularity of that fragment.

Skeletal and dental changes after surgical correction of mandibular prognathism.

Fifty cases of surgically corrected mandibular prognathism have been followed up and analyzed cephalometrically. This anatomy of relapse of the proximal and distal segments is described, as well as changes in the axial inclinations of the incisors. The physiopathology that may explain these spatial changes is advanced.

Experimental fractures of monkey mandibles.

Forty vervet monkey half mandibles, 20 with unerupted third molars and 20 with erupted third molars, were partially embedded in acrylic and loaded in an Instron tensiometer. Mandibles with unerupted third molars fractured at 15.8 +/- 2.5 kg while those having erupted third molars fractured at 26.4 +/- 4.2 kg. Mandibles having unerupted third molars were shown to be significantly weaker than the mandibles with erupted third molar (t = 8.45, P less than 0.001).

Surgical anatomy of the ascending ramus of the mandible.

A study of identifying the position of the lingula of the mandible on the external surface is described. The study was undertaken in an attempt to avoid damage to the inferior dental neurovascular bundle during operative procedures on the ascending ramus.

Familial polyostotic fibrous dysplasia.

A case of polyostotic fibrous dysplasia of the craniofacial type is presented, together with substantial evidence that this condition had a genetic basis in this patient. A review of the literature indicates that there is absolutely no previous evidence of a genetic basis to this condition. The possibility that the propositus suffered from polyostotic fibrous dysplasia of the Jaffe or the Albright type was excluded.