Alveolar bone resorption and maxillary sinus pneumatization occurring after dental extraction in the posterior region of the maxilla may be problematic when planning implant-supported rehabilitation. Various regenerative options are available, including guided bone regeneration, bone block grafts, and lateral sinus augmentation. These procedures are associated with significant complication rates, high morbidity, increased therapy duration, and high cost. Less invasive approaches, such as transcrestal sinus floor elevation, and using short implants have been proposed in an attempt to reduce these drawbacks. The aim of this study is to analyze available evidence to suggest predictable options and identify minimally invasive management of implant-supported rehabilitation in the posterior maxilla. This article concerns biologic mechanisms regulating new bone formation after maxillary sinus augmentation and examines characteristics of available implants and grafting materials to help the clinician select the most rational and convenient surgical approach according to specific situations.
The alveolar ridge undergoes pro- gressive modifications throughout a patient’s entire life. Many fac- tors, including periodontal disease, endodontic lesions, trauma, and tooth extractions, may contribute to the bone resorption process. Additionally, tooth loss in the pos- terior maxilla may further worsen this problem by promoting maxil- lary sinus pneumatization, and ridge preservation techniques seem only partially effective in preventing alveolar crest shrinkage. Radiographic studies on edentulous ridge dimen- sions showed that, in this area, bone augmentation procedures for stan- dard implant placement may be necessary in a substantial number of patients. Numerous surgical techniques and timing protocols have been proposed for implant-supported rehabilitation of posterior atrophic maxillae with limited bone heigh.
Both lateral and transcrestal sinus floor elevations are reliable surgical approaches to regenerate adequate bone volume and allow dental im- plant placement in the atrophic posterior maxilla. Strict adherence to established surgical protocols is mandatory to optimize clinical out- comes. In particular, adequate si- nus membrane elevation and close contact between bone walls and grafting materials are crucial pre- requisites for new bone formation in both approaches. Allografts, xe- nografts, and synthetic biomateri- als may be acceptable substitutes for autologous bone, as they pro- mote satisfactory new bone forma- tion (even if less than autograft) and guarantee better volumetric stabil- ity. Dental implants can be inserted simultaneously with the augmen- tation procedure if good primary stability is achievable. Delayed in- sertion, possibly improving the fi- nal quality of regenerated tissue, may be preferable in sinuses with low regenerative potential (a wide sinus which can be considered a “nonhousing” bone defect; elderly and/or low-responding patients). The use of rough implants seems to optimize survival rates, and there- fore the new generation of hybrid implants may be a promising alter- native to traditional implants, but further investigations are necessary.
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