The aim of this noninterventional, retrospective case series was to evaluate the outcome of immediately loaded implants in patients with failing dentitions that require bone tabling using a bone reduction guide and a surgical guide manufactured directly on three-dimensional (3D) stereolithographic models.
MATERIALS AND METHODS:
Consecutive patients with failing dentition and at least two remaining teeth who were treated in a single center between December 14, 2009 and September 23, 2013 were eligible. All patients receiving implants loaded with a hybrid prosthesis on the same day as extraction with their surgery planned on 3D models and performed using a surgical guide manufactured in a laboratory on the planning model were included. Patients who had undergone bone grafting procedures were excluded. Descriptive statistical analyses of available data were performed, including life-table calculations to derive a cumulative survival rate (CSR).
Two hundred twenty-eight patients (105 females and 123 males) received 1,657 implants (NobelActive) in 321 arches, in most cases 5 implants (range, 5 to 7) per arch. Ten preexisting implants were used. The mean insertion torque was 60.02 ± 13.1 Ncm (range, 15 to 75 Ncm). The definitive abutment was placed on the same day as surgery in all cases, and the definitive prosthesis (n = 304) was delivered after a mean of 7.9 ± 2.6 months. All implants were followed for 20.01 ± 11.3 months (range, 0 to 52 months) from implant insertion. Four implants (3 patients) had delayed loading, and one implant was left as a sleeping implant. Eight implants among six patients failed, two of the implants after prosthesis delivery. The CSR of the placed implants was 99.4% at implant level and 96.2% at patient level.
Planning on 3D models to remove bone and place implants using custom-made bone reduction and surgical guides with immediate loading on the same day as extraction of remaining teeth was safe and effective for implant survival and rehabilitation of patients with periodontitis and failing dentition.
Traditional dental implants in patients with advanced periodontal disease can be arduous, involving multiple surgeries, long treatment times, and high treatment costs. Therefore, many patients are unable to benefit from the use of dental implants. However, during the last decade, methods have been developed to simplify treatment by reducing the number of surgeries, treatment times, and associated costs.
During the healing process, implants become osseointegrated, and as their primary stability, which is purely mechanical, drops; simultaneously, the secondary stability (i.e., osseointegration) increases. Implants are vulnerable in this phase. Modern moderately rough surfaces and grooves are osteoconductive and promote osseointegration, which maintains the high stability that was initially achieved throughout the healing process. Furthermore, modern implant designs allow for high primary stability (e.g., high insertion torque ≥ 35 N cm) and immediate loading of implants, even when placed in extraction sites (e.g., failing dentitions). Immediate loading with a hybrid prosthesis is now an accepted treatment option for the full arch in both the maxilla and mandible . Immediate loading has achieved excellent results with various implant systems.
Surgical guides can facilitate the accurate placement of implants during insertion procedures . These guides were initially produced by dental labs on gypsum dies. However, recent advances in CAD/CAM technology utilizing stereo-lithographic manufacturing of the guides have improved the production and shown a higher predictability of outcomes with better planning and accurate implant placement.
There is some evidence that placing the definitive abutment on the day of implant insertion can improve the chances of success. Further, patients with a failing dentition usually wish to get teeth that are functioning the same day of surgery. Patients report higher satisfaction during osseointegration of implants if they receive the prosthesis immediately compared to delayed loading protocols.
Implants can be placed in a tilted manner in contrast to the upright position of natural teeth Tilting implants allows use of longer implants and is enabled by “multi-unit-abutments. Furthermore, it spares areas such as nerves, sinuses, or vessels and allows a wider anterior-posterior spread to support the prosthesis, thereby reducing the extent of cantilevers, which can fracture and are unfavorable for loading implants. In addition, tilting can help avoid major bone grafting. There is sufficient evidence that tilting does not adversely affect implant success.
Tilted implants and immediate placement of implants to replace failing dentitions are demanding procedures. Surgical templates facilitate placement of implants in the planned position and can be created with planning software using CT or CBCT data. Another option would be to plan and manufacture the guides on 3D stereo-lithographic models. Planning implant positions with computer-based methods and stereo-lithographic surgical templates achieves high cumulative survival rates (CSR) for implants at 1 year of follow up (9). However, to date, no study has planned the amount of bone reduction and placed the location of the dental implants directly on three-dimensional (3D) stereo-lithographic models. In such an approach bone reduction is first performed directly on the 3 D model by the oral surgeon. The surgeon then performs the implant osteotomies directly on the 3D models. This is followed by fabrication of both the bone reduction guide and the surgical guides. The 3D model allows further evaluation of the planned placement according to the anatomical structure of the patient prior to actual placement and manufacture of the guide on that basis. Here, we performed a retrospective evaluation of implants placed and immediately loaded in a series of consecutive patients with failing dentition using both a bone reduction and a surgical guide that were manufactured directly on 3D models.
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