Survivability of Dental Implants Placed in Atrophic Maxillae Using Open Sinus Elevation Technique With and Without Bone Grafting Material. A Randomized Controlled Clinical Trial

It is well documented in literature that after dental extractions, the alveolar ridge will undergo some changes in volume both in hard and soft tissue both in the anterior and posterior region of the oral cavity. This adds challenges to properly place dental implants following tooth extraction in a good prosthetic position, specifically in the Maxillary posterior region due to the proximity of the Maxillary Sinus. Maxillary sinus pneumatization is an ongoing process that occurs naturally causing increased maxillary sinus volume on the expense of the alveolar ridge. When the combination of sinus pneumatization and bony atrophy of the maxilla occurs following tooth extractions together over time, the edentulous ridge dimension can be very minimal.

Numerous techniques were suggested to facilitate implant placement in atrophic posterior maxilla. The first proposed technique was the Maxillary Open sinus technique, it was first proposed by Dr. O. Hilt Tatum at an implant meeting in Alabama, however, Boyne and James in 1980 were the first to publish this surgical technique. In order to regain the vertical dimension, open sinus technique was originally performed in a staged manner over two steps, where the implant was placed after a healing period after Maxillary sinus augmentation, however, the different sinus elevation techniques, whether staged or one step did not seem to affect the implant success rate and showed bone gain of up to 12 mm.

Some authors suggested less invasive techniques that were of less discomfort to the patient, more cost effective and less time consuming. Summers proposed the osteotome technique, where similar to traditional drilling, an osteotomy is prepared using a set of osteotomes 1mm short of the sinus floor, followed by fracturing of the floor using the proper sized osteotome with bone graft material, which will allow the introduction of bone grafting material into the sinus floor, followed by the placement of the dental implant. However it was limited to 5 mm in terms of bone gain compared to 12 mm bone gain in the open sinus technique. Over the years, modifications to Summers original technique were made. Short dental implants were proposed; however, a review of the literature reveals implants shorter than 10 mm often have a higher failure rate than longer implants. These complications may be related to an increase in crown height, higher bite forces in the posterior regions, and less bone density. As a result, methods to decrease stresses to the bone-implant interface are to be researched. This necessitates and puts the clinician in a situation where the open sinus procedure is sometimes inevitable.

The formation of bone in elevated sinus space was a mystery and its reason was unknown. However a histological study showed the osteogenic potential of the Schneiderian membrane when it was subcutaneously placed in rats suggesting that bone genesis could be directly related to the presence of the Schneiderian membrane in the maxillary sinus regardless the presence or absence of a bone grafting material. This technique was based on the concept that the lifting of the sinus membrane and the establishment of a compartment with a blood clot could result in new bone around the inserted implants in a similar way that bone-graft materials maintain the augmented space and promote osteogenesis.