The implant must have initial stability. Vertically, a minimum of 4 mm of bone in the apical part of the alveolus is necessary to get implant stability. Class I or II bone quality (anterior mandible) is better than class III or IV (posterior maxilla). Laterally, if there is not enough bone envelope around, look for longer (bicorticalization) and, if possible, wider self-tapping or taper implants.
Placement of the implant should be within the tooth position both buccolingually and mesiodistally. To achieve this, in monoradicular tooth extraction, the starting point should be located towards the buccal end of the crest in the mandible and towards the palate in the maxilla.
Concerning bicorticalization to achieve implant initial stability, that is not a problem as long as the alveolar bone maintains its integrity. For a screw-retained crown, an immediate anterior maxilla implant should be inserted towards the palatal cortical plate of the alveolus, and towards the buccal cortical plate of the mandibular alveolus. For a cement-retained crown, the insertion direction can more easily follow the direction of the alveolus.
TIP The final esthetic look is the direct result of work done properly at the bone, soft tissue and prosthetic levels. TIP Placement of several implants is influenced by general and local factors. Single implant placement is influenced only by local factors.
Rationale of the Immediate Implant
There are enough supporting scientific data to consider that the best time to place an implant is, whenever possible, right after the tooth's extraction. This was first reported by Schulte in 1978 using a polycrystalline aluminium surface implant. An increasing number of clinical studies demonstrate that the immediate placement of implants into fresh extraction sockets renders success rates similar to those reported for conventional implant placement, both in animals and in humans.
Implants placed at the time of tooth extraction osseointegrate without fibrous tissue interposition between the implant surface and surrounding bone. Implants placed into extraction sockets with four bony walls can be expected to heal uneventfully with bone.
In humans, Wilson found that the horizontal component of the defects was the most critical factor in dictating the final amount of bone-implant contact after a month healing period.
With small, horizontal, peri-implant defects the use of a barrier membrane is not necessary, provided the socket walls are intact, a favorable defect morphology is present, and a titanium implant with an appropriate surface is placed.
When screw-type implants were placed without the use of barrier membranes or other regenerative materials into extraction sockets with a bone-to-implant gap of 2 mm or less, the clinical outcome and degree of osseointegration did not differ from implants placed in healed, mature bone25. Furthermore, the placement of various grafting materials into extraction sockets may interfere with the normal healing process. However, immediate implant placement and augmentation of sites with barrier membranes have been reported by several authors.
TIP In immediate loading implants, the bone healing and osseo-integration phases occur simultaneously. In immediate loading implants in fresh sockets, the bone growing phase also occurs simultaneously.