Graft Remodeling following Transcrestal Sinus Floor Elevation via the Gel-Pressure Technique (GPT) and Pasteous Nano-Crystalline Hydroxyapatite Bone Substitute

Bernhard Pommer,Ewald Unger,Dieter Busenlechner,Georg Mailath-Pokorny,Georg Watzek,Robert Haas,Rudolf Fürhauser

doi:10.3390/ma8063210

Bernhard Pommer, Ewald Unger + Show 5 more

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https://doi.org/10.3390/ma8063210

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Abstract

Bone grafting of the maxillary sinus is attempted to compensate for sinus pneumatization and permit reliable insertion of endosseous dental implants for prosthetic rehabilitation. The aim of the present clinical investigation was to study bone regeneration four months after transcrestal sinus floor elevation via the Gel-Pressure Technique (GPT) and application of pasteous nano-crystalline hydroxyapatite bone substitute. A total of 25 patients with deficient alveolar ridges in the posterior maxilla (mean residual bone height: 4.7 ± 1.8 mm) were subjected to 32 flapless transcrestal sinus floor augmentations and simultaneous insertion of 40 implants. Sinus membrane elevation height averaged 11.2 ± 2.7 mm and minimal vertical graft resorption of 0.1 mm was observed after four months. Radiographic bone density averaged 460 Hounsfield units in regions adjacent to the native jawbone (1 to 7 mm distance), while reduction of bone density by −7.2%, −11.3%, −14.8%, −19.6% and −22.7% was recorded in more apical regions of 8, 9, 10, 11, and ≥12 mm distance to the original sinus floor, respectively. The results suggest that graft remodeling is completed up to a distance of 7 mm within a healing period of four months after sinus augmentation using nano-crystalline hydroxyapatite bone substitute material.

Highlights

Following postextraction alveolar bone resorption and pneumatization of the maxillary sinus cavity the quantity, as well as quality of available bone for dental implant placement in the edentulous posterior maxilla is frequently limited [1]
The formation of vital bone to allow for osseointegration of delayed or simultaneously placed implants is initiated by coronal displacement of the maxillary sinus mucosa (Schneiderian membrane) with or without addition of autologous bone and/or bone substitute material [3]
These findings suggest that graft remodelling is completed up to a distance of 7 mm into the sinus graft within four months, while the area between 8 and 11 mm shows reduced graft remodelling with continuous decrease of radiographic bone density from −7.2% in 8 mm distance to −19.6% in 11 mm distance

Summary

Introduction

Following postextraction alveolar bone resorption and pneumatization of the maxillary sinus cavity the quantity, as well as quality of available bone for dental implant placement in the edentulous posterior maxilla is frequently limited [1]. The formation of vital bone to allow for osseointegration of delayed or simultaneously placed implants is initiated by coronal displacement of the maxillary sinus mucosa (Schneiderian membrane) with or without addition of autologous bone and/or bone substitute material [3]. Average survival rates reported in systematic reviews on dental implants placed in the grafted maxillary sinus range between 91.5% and 92.6% for the lateral approach, compared with mean survival rates between 93.5% and 96.4% following the transcrestal approach [5,6,7,8]. Comparisons are difficult to be made, due to relevant differences in confounding variables, such as residual bone quality and quantity, implant macrogeometry and surfaces, timing of implant placement and prosthetic loading, type of prosthesis and dentition of the opposing arch, patient-related determinants, as well as grafting materials or mixtures [9]

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