INTRODUCTION
The goal of the implant surgeon is to place the implant in the ideal position, to support the prosthesis for the best long term prognosis, while managing important anatomical landmarks. With the aid of Cone Beam CT scans the implant surgeon is able to evaluate, in three dimension, the ridge, important anatomy, as well as pre-plan implant placement in the most ideal position. Advancements in technology such as CT Scans, Soft Tissue Scans, and Dynamic Surgical Navigation allow the surgeon to better serve the implant needs of his/her patients. The following is a case presentation on how I incorporate dynamic surgical guidance, using the Inliant Surgical Navigation System, in preparing the osteotomy and manipulating the maxillary sinus floor to allow placement of my preferred implant size for the posterior maxilla following extraction, site development and healing of the upper right first molar (Tooth #16).
METHODS AND RATIONALE
It is my personal preference to place a wider and longer fixture in the posterior maxilla where bone quality and density is considered less than ideal and where the highest incidences of implant failures occur. While it has been shown that short implants function and have predictable long-term success, this is likely a reflection of shorter implants used in the posterior mandible where bone quality and density are favorable for allowing good initial stability and long-term support for the implant and prosthesis. The posterior edentulous maxilla poses different challenges in choosing, preparing and placing implants that will have good long-term success. The posterior maxilla is generally comprised of lower density and poorer quality bone (D4 Misch classification).
Pneumatization of the maxillary sinus as well as crestal bone resorption following tooth extraction limit the residual bone, visibility and access during osteotomy preparation. My personal choice is to place wider and longer-bodied implants in order to increase bone-to-implant contact. As such, in nearly all of my posterior maxillary implant placements I utilize the maxillary sinus through either a lateral window approach or crestal approach to separate the schneiderian membrane, allowing placement of implant(s) with or without graft. The crestal approach osteotomy can be done using many different tools and surgical kits. My personal experience began with the use of osteotomes manually approaching and penetrating the sinus floor, progression to the use of tapered compressing drills (MIS sinus and bone compression kit). For the past four years I have used the CASKIT from HiOssen (Osstem Implant Company). The functionality, efficacy and science behind this wonderful kit are topics for another presentation, but this is the sole modality by which I do crestal approach sinus lift/bumps for the posterior maxilla. The system is designed to use parallel drills with measured stoppers (resting against the ridge crest) to incrementally approach the sinus floor and allow penetration without perforating the schneiderian membrane. When the surgeon evaluates, interprets the Cone Beam CT Scan and does his/her measurements of the residual ridge height prior to sinus floor penetration, there is often some variance in the measurements based on the person manipulating the scan, and the incline and anatomy of the sinus floor.
When the surgeon initiates surgery with a pre-determined vision of penetrating the sinus floor at “X” milimeters, he/she soon realizes the reality of surgery proves otherwise and this can be confusing and frustrating during surgery. These variances are often the result of the position and preparation of the osteotomy when approaching the sinus floor. Slight changes in angulation in any plane can result in a delay or premature penetration of the sinus floor from the anticipated, preplanned CT scan (Figures 1a-1b). This is the reality of free-hand osteotomies in any area of the mouth and most certainly can be challenging when one is trying to approach and penetrate the sinus floor.
Using the Inliant dynamic navigation technology, I am able to pre-plan the implant position and, during surgery, visualize the drill, “in real time”, as it moves through the planned osteotomy. This sharply reduces the variance in angulation and allows me to visualize the relationship of the drill tip to the sinus floor regardless of slope of the sinus floor, inclines, bony septum, or other anatomical features of the sinus. Thus, the moment of sinus floor “penetration” involves far less guess work and stress during the surgery.
THE CASE
The patient presented with a chief concern of “pain and swelling in the upper right back tooth”. She had no sensitivity or reaction to thermal stimulus; however, she felt her tooth “was swollen and hurt when she attempted to chew on it”. She points to tooth #16 as the source of her pain.
EXTRA-ORAL EXAM
No facial asymmetry, edema or lymphadenopathy were noted. TMJ function and range appeared normal.
INTRA-ORAL EXAM
There were no visible failing restorations, or cracked/fractured teeth in quadrant one. The soft tissues were normal in appearance with the exception of the buccal m
arginal gingiva, around tooth #16, which was noticeably inflamed and tender to touch. Some exudate was expressed on application of pressure in the region. Probing depths were in the range of 1-4mm throughout the quadrant with the exception of the mesiobuccal aspect of #16 which probed 8mm. No mobility was noted on any of the teeth within the quadrant. With the patient’s consent, a peri-apical radiograph of the region was taken. Review of the radiograph revealed an area of radiolucency around the mesial root. The tooth showed to have previous endodontic treatment. There was no sign of recurrent caries or marginal failure, either clinically or radiographically.
