Resorption beneath silastic mandibular implants. Effects of placement and pressure.

Arch Facial Plast Surg. 1999 Oct-Dec;1(4):261-4; discussion 265

Authors: Pearson DC, Sherris DA

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.

PMID: 10937112 [PubMed - indexed for MEDLINE]

Mersilene mesh chin augmentation. A 14-year experience.

Arch Facial Plast Surg. 1999 Jul-Sep;1(3):183-9; discussion 190

Authors: Gross EJ, Hamilton MM, Ackermann K, Perkins SW

During the past 20 years, a variety of alloplastic materials have been introduced for chin augmentation. Mersilene mesh (Ethicon, Sommerville, NJ), introduced in 1950, demonstrates many qualities that make it an ideal implant. This article reviews the senior author's (S.W.P.) successful 14-year experience using Mersilene mesh chin implants. Between 1983 and 1997, 264 patients underwent chin implantation procedures. The results show a low rate of infection (0.8%) and displacement (1.5%). There were 14 temporary paresthesias and no cases of permanent anesthesia. There were no incidences of absorption, rejection, or extrusion. Mersilene provides a soft, natural appearance to the chin, and it continues to be our choice for chin implantation.

PMID: 10937101 [PubMed - indexed for MEDLINE]

The bridging lateral mandibular reconstruction plate revisited.

Arch Otolaryngol Head Neck Surg. 1999 Sep;125(9):988-93

Authors: Blackwell KE, Lacombe V

BACKGROUND: Lateral oromandibular reconstruction using a soft tissue free flap with a first-generation locking mandibular reconstruction plate (MRP) was rejected in a previous series by the senior author (K.E.B.) owing to a high incidence of delayed plate extrusion through the cheek skin. OBJECTIVE: To reexamine this method of reconstruction using a second-generation, low-profile MRP. PATIENTS AND DESIGN: A prospective case series of 27 patients with segmental defects of the lateral mandible after treatment of head and neck cancer. SETTING: An academic tertiary care referral center. INTERVENTION: All patients had mandibular continuity restored using the Leibinger Locking System (Stryker Leibinger Inc, Kalamazoo, Mich) MRP. Associated soft tissue defects were repaired using radial forearm (n = 22) or rectus abdominis (n= 5) free flaps. MAIN OUTCOME MEASURE: Incidence of hardware-related complications. RESULTS: All microvascular flap transfers were successful. One patient experienced a plate fracture 9 months after reconstruction. Only 1 patient experienced external plate exposure, 6 months after undergoing reconstruction of a through-and-through defect. Reconstruction was successful in 25 (93%) of the cases after a median follow-up period of 19.5 months. CONCLUSIONS: The high incidence of external plate exposure in patients undergoing lateral oromandibular reconstruction using soft tissue free flaps and first-generation locking MRPs may have resulted from a plate geometry that was prone to result in extrusion. After a similar length of follow-up, the incidence of reconstructive failure was reduced by using a low-profile, rounded-contour MRP. Final assessment of the durability of this technique will require long-term follow-up.

PMID: 10488984 [PubMed - indexed for MEDLINE]

Volume-length impact of lateral jaw resections on complication rates.

Arch Otolaryngol Head Neck Surg. 1999 Jan;125(1):68-72

Authors: Arden RL, Rachel JD, Marks SC, Dang K

OBJECTIVE: To study the relationship between soft tissue volume loss and bone resection length following lateral segmental mandibulectomy with plate reconstruction and complication rates. DESIGN: Retrospective case review of 31 patients (1989-1996), with average follow-up of 37.2 months, who were treated by lateral composite resection for oral cavity and/or oropharyngeal malignancy with primary reconstruction by defect-bridging plates. SETTING: Academic tertiary care referral center. INTERVENTIONS: Thirty patients had stainless steel and 1 patient a vitallium reconstruction plate to restore mandibular continuity. Soft tissue defects were repaired with pectoralis myocutaneous flaps (n = 25), skin grafts (n = 4), a radial forearm free flap (n = 1), or primary closure (n = 1). All patients received preoperative (n = 6) or postoperative (n = 25) radiation therapy. MAIN OUTCOME MEASURES: Overall and hardware-related complications. RESULTS: All 31 initial soft tissue repairs were successful. Subsequent complications occurred in 14 patients (45%), which included plate exposure (29%), loosened screws requiring hardware removal (29%), fistula (14%), local wound infection (14%), osteomyelitis (7%), and plate fracture (7%). Average time to complication was 7.7 months. Complication rates were 81% for bone defects greater than 5.0 cm, and 7% for those less than 5.0 cm. Bivariate analysis indicated bone resection lengths greater than 5.0 cm to be a significant predictor of both hardware-related (P = .02) and overall complications (P = .005), whereas soft tissue volume resections greater than 240 cm3 were found only to be marginally significant (P = .04) for overall complications. CONCLUSION: Extirpative losses involving more than 5 cm of bone, or tissue volume greater than 240 cm3, are associated with unacceptably high complication rates when reconstructed with solid screw stainless steel plates and this warrants consideration of alternative techniques for long-term stability.

PMID: 9932591 [PubMed - indexed for MEDLINE]