Sherris, David A.

Objective To evaluate the extent to which silicone rubber mandibular implant (Silastic; Dow Corning, Midland, Mich) pressure and placement (supraperiosteal or subperiosteal) affect underlying mandibular resorption. Design A randomized, controlled animal trial. Subjects Ten mixed-breed adult hounds. Interventions Each animal's mandible was implanted with 6 Silastic blocks, 3 inserted supraperiosteally and 3 subperiosteally. Within each grouping of 3 implants, pressure was varied from "minimum" to "moderate" to "maximum" by compressing the implant with titanium miniplates. After 4 months, the animals were killed and their mandibles sectioned for microscopic examination. Results Mandibular resorption occurred in varying degrees beneath all implants by the end of the study period. The extent of resorption was consistent with retrospective studies in humans. No statistically significant difference was found between supraperiosteal or subperiosteal placement of the implants. However, higher-pressure implants tended to produce less resorption than lower-pressure implants. Conclusions While some bone resorption seems inevitable with Silastic mandibular implants, these results would seem to suggest that the placement of implants above or below the periosteum need not be a concern for the surgeon attempting to minimize this consequence. On the other hand, increased pressure may actually decrease resorption, contrary to current assumptions.

Objectives To develop a method to quantify nasal tissue resilience, to establish the normal range for persons without nasal obstruction, and to measure the changes in tissue resilience resulting from standard open rhinoplastic techniques. Methods A new device is described that determines nasal tissue resilience. Measurements on the nasal tip were obtained in triplicate at 5 distinct anatomical sites. Normal values (N = 60) were stratified for both sexes into 3 different age groups. Preoperative and postoperative measurements were also obtained in 6 patients who underwent open rhinoplasty for airway obstruction. One patient who underwent intranasal valve repair was included for comparison. All operative patients underwent preoperative and postoperative rhinomanometric measurements. Results Across all age and sex groups the anterior septal angle is the firmest area of the nasal tip. The mean tissue resilience over the interdomal area and the midcolumella is significantly greater in men than in women. The resilience of the interdomal area exhibits an age effect, with decreasing stiffness over time. The postoperative changes seen correlate well with the placement of structural grafts during rhinoplasty. Conclusions Nasal tip support can be quantified. Normative values have been established, which allow one to identify areas of inadequate tip support in persons with nasal obstruction. Alterations in tip support resulting from surgical intervention can be quantified. Open rhinoplasty techniques are an excellent tool to restore deficiencies in nasal tip support.