Implant design and implant selection, posterior zone
- Short and tilted implants can avoid bone grafting.
- In the posterior maxilla, if the residual alveolar bone height is 3 to 6 mm, a transcrestal approach and placing 8 mm implants may lead to less complications than a lateral window approach.
- Wide-diameter implants (≥ 5 mm) offer a greater surface area and better primary stability in case of post-extractive implants, replaced implants, and poor bone density.
In the posterior jaw areas, tooth loss is usually associated with alveolar bone resorption and sinus pneumatization or alveolar nerve superficialization.
Today, the most commonly used implant design is a tapered body, with a moderately rough implant surface, and conical implant-abutment interface. Furthermore, the platform shifting concept, through the use of a smaller abutment diameter, introduces an horizontal inward component to the establishment of the biological width, (that otherwise is a vertical process), contributing in preserving the marginal bone level.
Short implants (5 mm) can be successfully loaded in mandibular and maxillary bone, but poor crown/ implant (C/I) ratios may lead to excessive crestal bone loss.
Tilted implants can be used to avoid the need for bone grafting. They might compromise the prosthetic emergence profile and long-term hygienic maintenance. Although no difference between axial and tilted implants has been reported, they might compromise the prosthetic emergence profile and long-term hygienic maintenance.
Different augmentation techniques in the maxillary sinus with simultaneous or delayed installation of implants have been reported. The insertion of implants in combination with maxillary sinus floor elevation using a lateral window approach is a predictable treatment option with high implant survival rates and few surgical complications. Nevertheless, according to a recent Cochrane systematic review, for residual alveolar bone heights of 3 to 6 mm, a transcrestal approach to lifting the sinus lining and placing 8 mm implants may lead to less complications than a lateral window approach.
Implant placement in fresh molar extraction sockets still allows achieving of good primary implant stability by using, for example, wide and/or tapered implant designs. Wide-diameter implants (≥ 5 mm) with reduced length offer a large bone-to-implant contact (BIC) area and better primary stability. Increasing the width of implants has been shown to reduce the amount of biomechanical stresses at the crestal bone level which may reduce potential marginal bone loss. Computer-guided implant protocols may help clinicians to place straight and tilted implants, avoiding elevation of large flaps and challenging surgical techniques, causing less pain and discomfort to patients.