Influence of a collagen membrane positioned subjacent the sinus mucosa following the elevation of the maxillary sinus. A histomorphometric study in rabbits

The aim of the present systematic review of the literature was to evaluate biomaterials performances considering new bone formation estimated through histomorphometric analysis of bone biopsies from human subjects after maxillary sinus floor elevation.

To evaluate the effect of guided bone regeneration (GBR) in combination with or without deproteinized bovine bone mineral (DBBM) and/or an enamel matrix derivative (EMD) on the healing of critical-size calvarial defects. Forty rats were used. In all animals, a standardized critical-size calvarial defect was created surgically. The animals were randomly allocated into 4 groups of 10 animals each. Group A: One calvarial defect was left untreated, while the galeal and the cerebral aspect of the contralateral defect were covered with a bioresorbable membrane (GBR). Group B: One calvarial defect was filled with EMD, while the contralateral defect was treated with GBR and EMD. Group C: One defect was filled with DBBM, while the contralateral defect was treated with combination of GBR and DBBM. Group D: One defect was filled with DBBM combined with EMD, while the contralateral defect was treated with combination of GBR, DBBM and EMD. The healing period was 4 months. Five specimens from each group were macerated and the length, the width and the vertical dimension (thickness) of the remaining defect were evaluated by a stereomicroscope. The remaining specimens in each group were analyzed histologically. The defects of the macerated specimens that were left untreated or were treated only by EMD, DBBM and combination of EMD and DBBM did not present predictably complete healing of the defects. All the defects where GBR was applied alone or combined with DBBM and/or EMD presented always complete healing (P<0.05). The combined use of GBR with EMD and/or DBBM did not offer any significant advantage above GBR alone in terms of healing of the length and the width of the defect. However, the vertical dimension of the defect was significantly higher (P<0.05) in the GBR-treated specimens of Groups C and D. The histological analysis supported these findings. The predictability of bone formation in critical-size defects depends mainly on the presence or absence of barrier membranes (GBR). The combined use with deproteinized bovine bone mineral and/or enamel matrix proteins did not significantly enhance the potential for complete healing provided by the GBR procedure.

The most frequent intraoperative complication with sinus elevation is perforation of the schneiderian membrane. In most instances, the repair of this perforation is necessary to contain particulate grafting material and complete the procedure. New techniques are presented here for the management of large perforations of the schneiderian membrane. A bioabsorbable collagen membrane is stabilized outside the antrostomy and then folded inward to create either a new superior wall that can obliterate a large perforation or a "pouch" that can completely contain the particulate material. This can make it possible to complete a procedure that otherwise may have had to be aborted by preventing dispersion of the particulate graft within the sinus cavity. Clinical cases are shown, along with follow-up at 6 to 9 months, demonstrating histologic and/or radiographic evidence of success, continued sinus health, and superior vital bone formation. The authors have used this technique on 20 consecutive patients without experiencing any procedural failures.