Dr. Guido Schiroli – D.T. Stefano Silvestrelli
Guido Schiroli C.so Buenos Ayres, 6\12 16129 Genova, Italy
email : schirol@tin.it
Abstract :
The aim of this study is to present a protocol to obtain simply and accurately the provisional bridge before the implant surgery. Respecting this approach is possible to deliver the bridge immediately after the surgery deriving from the 3D model obtained with Cad-Cam technologies, avoiding the immediate impression and shortening the chairside time of the original immediate implant load protocol.
With this procedures the implants are also placed respecting a virtual design using the stents obtained by the Cad-cam technology. The implant placement is accurate and safty frequently without any surgical flaps needing.
The advantages of this procedure are multiple in terms of safty, accuracy and ergonomy :
1) Shortening of surgical time
2) safty of flapless surgery
3) Ideal implant position
4) The ideal emergence profile
5) immediate splint of the single units according to the the immediate load protocol predictability.
Introduction
The successful of the ossointergration has been widely described both in total and partial edentulous patient 1-2 .
Beside, the successful rate has been associated with implants load position and direction and the main risk factor about implant failure, when the osseointegration is reached, is about the wrong position of this one compared to the definitive bridge and, as final analysis, about the functional load direction 3 . For this reason, it’s important to plan in advance, before the surgery, what will be the relationship between the final dental restoration and the implant position 4-5 . A basic phase of planning procedure about the implant bridge is the imaging, that is the radiological acquisition before the surgery necessary for the evaluation of quantity \ quality bone available 6. For many clinicians the panoramic radiograph is still the imaging tool of choice when planning for implant reconstruction despite its two dimensional limitations and inherent distortion factor 7-8
However, the evolutionary trend, and increased acceptance of dental implants as a predictable treatment alternative has been greatly enhanced by technological advances in three dimensional imaging and have improved substantially since its inception, including overcoming the potential inaccuracies of traditional panoramic and periapical radiography 8. Using available software as a diagnostic aid , allows the clinician to develop multiple treatment plans quickly and efficiently. It’s possible, therefore, execute very exact evaluation about available size bone (measurement and calibration) and, not last, place the implants, drawing them inside the image of patient, very simply and intuitive, in order to simulate the operation 9-10. The implant placement is also driven by the position of the final restoration visible into the Ct images as the patient wear the radiopaque stent obtained from the conventional wax-up procedure 11-12.
The Company who produce the software take out a patent on technology for transferring drawing CAD files ( in this case the patient TAC ) to a CAM process that build, by a laser robot, 3D models with stereolytographic or prototyping technology identical with the image and origin files . This process applied to the medical and maxillofacial procedures, allow to obtain 3D models exactly identical with the patient anatomy and guides 13-14-15 that drive the surgeon to the approprite implant placement. The functional and immediate load has been showed recently, as clinical than histological, improves positively the bone response around the oral implants 16.
An accurate preoperative planning matched to the prosthetic placement of implants and the immediate splint of the single units represent two paradigm of the immediate load protocol. As already described, the functional and the early load on osseointegrated implants is more predictable and maintanable if the provisional or definitive bridge delivery, it will be quick as possible 13-16.
The accuracy of immediate restoration in terms of functional splinting, represent one of the keys in order to keep and maintain the initial necessary stability and to reach a final osseointegration 17-18.
Materials and methods
Multiple total 1 and partial 2 edentulous patients have been treated with osseointegrated implants supported prosthesis. All patients received immediate implant load with the immediate provisional delivery. After conventional wax-up and radiopaque stents all patient have been send to the radiologist for the Ct scan acqisition. Receiving the images all implants ( primary and secondary retention too ) were drawn into the dedicated software and the surgical guide have been receive from the Company.
Using the guide a master cast model was obtained and the provisional dentures and abutments are assembled on the same model. After local anesthesia the mucosa supported surgiguides have been screw throug the guide and all implants were placed exactly were drawn before. The screw retained prosthesis was deliver at the time of surgery 3-4.
Discussion
Different protocols for both surgical and prosthetics, clinically or planning, have been proposed to gain and maintain the immediate load in osseointegration therapy.
Considering all anatomical or functional variables all protocol display the same key factor: a predominant prosthetics planning that set the following surgical step giving a special principle to the definitive restoration.
The key factors of these procedures obtained in “virtual surgery “seems the following:
1) Cross sectional position of implants respecting the also the three dimensional anatomy and parallelism to obtain an equilibrate load
2) The biomechanical evaluations of the implant shape and definitive crown morphology
3) The abutments design correlating screw or cemented implant bridge
4) The surgical device for the control of all variables respecting the biology of the natural structures and the single implants units.
Conclusions
The protocol that have been called “SS Customized implantology“, original for the pre-prepared steps give us the chance to introduce a new special device useful to control the surgical implant placement that in our experience offer the needed predictability to the immediate load implant performances.
Considering the limits of other protocol available and the literature data we can conclude remembering the following facts:
1) Any restriction in making decision to the implant brand solution
Tapered v\s cylindrical shape
Internal v\s external connection
2) Ideal Implant position respecting the bone structure available and the restorative planning
3) Any surgical impression
4) Any waiting
5) Any surgical variables
6) Any micro movements influences
7) Any surgical risk
8) Any biological risk
A summary of the cumulative factors that give the expectation to the patient .
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