Augmentation Techniques – the Basis of Aesthetic

Class IV/V defects Classes IV and V refer to bone areas not capable of accommodating implants in their current state because the available bone volume at the planned site is inadequate. Class IV is defined by the absence of the buccal lamella; class V is additionally charac- terized by vertical bone loss. Situations of this type are primarily encountered in the anterior segment after trauma, multiple apical resection or extensive inflammation. Ridges too narrow for implant place- ment are also observed in situations of agenesis or teeth having been lost a long time back. According to investigations by Buser and Grunder, a fixture whose vestibular surface is only covered by 1 mm of bone cannot possibly be stable. This finding is consistent with our own experience and is particularly true of the anterior segment. For stable long-term results, a bone thickness of at least 3–4 mm is required. Other- wise the peri-implant tissue will sooner or later recede, thereby causing aesthetic deficits. Class IV and V defects require a step-by-step approach, the primary objective being to augment the bony defect. Very often, this has to be followed by additional procedures to optimize the soft-tissue structures. Preparing the ground for a tooth-like emergence profile by conditioning the peri-implant soft tissue is a major concern in the restorative phase. Enossal bone harvesting The following bone regions can be eligible for har- vesting: • Peri-implant environment (drilling chips, bone scraper) • Tuberosity • Mandibular angle, retromolar mandibular segment • Symphysis Which of these regions is appropriate to use will depend on the following criteria: • Required bone volume • Anatomical conditions at the harvesting site • Bone quality at the harvesting site • Postoperative trauma by bone harvesting EDI Case Studies 6 Fig. A1 Minor bony dehiscence on the buccal aspect. Fig. A2 Bone chips harvested with a scraper from the peri- implant envi- ronment. Fig. A3 Bone chips col- lected during implant bed preparation. Fig. A4 Defect filling with harvested bone. Autolo- gous bone is introduced directly into the defect, xenologous material (Bio- Oss, Geistlich) is added to protect against resorp- tion and for contouring. The defect is then covered with a resorbable membrane (BioGide, Geistlich).