A stent for presurgical evaluation of implant placement

Feasibility and needs for simultaneous or staged bone augmentation to place prosthetically guided dental implants after extraction or exfoliation of first molars due to severe periodontitis

BACKGROUND

The aim of this study was to retrospectively assess bone volumes, healed ridge topography and possibility to plan prosthetically guided implants (PGI) at least 6 months after extraction or exfoliation of first molars as a consequence of terminal periodontitis (EEFMP).

MATERIALS AND METHODS

45 subjects with stage III-IV periodontitis providing 74 extraction sites (maxillary = 51 and mandibular = 23) were included. The degree of residual periodontal support on each root was assessed by combining periodontal and radiographic data. Digital planning of PGI with 4.8/4.1 mm diameter, 8 mm long, root-form dental implant and need for bone augmentation (BA) were performed using CBCT with a radiographic stent. Possibility of standard implant placement (STANDARD) and need for simultaneous or staged BA were assessed.

RESULTS

Planning PGI placement was possible in all cases. For a 4.8 mm diameter implant, STANDARD was possible in 37.8% of the sites, 33.8% required BA at the time of implant placement, and 28.4% required staged BA before PGI. The use of 4.1 mm rather than 4.8 mm diameter implant allowed STANDARD in an additional 8.1% of cases that originally required simultaneous BA/osteotome sinus floor elevation (OSFE). The level of periodontal bone loss did not predict the complexity of implant placement, but significant differences were observed comparing maxillary with mandibular sites.

CONCLUSION

PGI planning at sites with first molar loss due to terminal periodontitis is possible but poses great challenge to rehabilitation, often requiring advanced augmentation procedures and sinus augmentation.

Comparison of the Accuracy of Image Registration Methods for Merging Optical Scan and Radiographic Data in Edentulous Jaws

PURPOSE

The image registration of optical scans to radiographic images is essential for performing computer-guided implant surgery. This study aimed to evaluate the effect of different image matching conditions on the accuracy of image registration for computer-guided implant surgery in completely edentulous jaws.

MATERIALS AND METHODS

The optical scan image of a completely edentulous study model was registered to the respective cone-beam computed tomography data using three different image matching conditions: small point (SP), large point (LP), and entire surface (ES). For the SP and LP groups, gutta-percha markers (1.0 and 3.0 mm in diameter) were attached to a base template, and a radiopaque impression material was relined on the intaglio surface of template in the ES group. Image registration was performed by 20 operators in the images obtained from each group at an interval of 2 weeks (n = 20 in each group), and the registration accuracy was assessed by calculating the aligned position of the edentulous arch image. One-way analysis of variance with Tukey post hoc tests was used to compare the results among the groups (α = 0.05).

RESULTS

The mean registration error was significantly larger in the SP group (0.52 ± 0.19 mm) than in the LP group (0.29 ± 0.08 mm) and ES group (0.27 ±0.06 mm) (F = 24.689, p < 0.001). No difference was found between the LP and ES groups. The image matching discrepancy was more homogeneously distributed on the arch in the ES group than in the other groups.

CONCLUSION

The accuracy of image registration is affected by the size of the congruent area shown in the optical scan and radiographic images. The entire surface-based matching method is more accurate as compared to the small point-based matching method in the image registration for implant planning in full edentulous jaws.

Presurgical implant-site assessment and restoratively driven digital planning

Cone-beam computed tomography imaging and 3-dimensional (3D) computer software allows for greatly enhanced visualization of bone, critical anatomy, and restorative plans. These systems allow clinicians to digitally process 3D images and restorative templates, facilitating dental implant planning. This article highlights the use of contemporary methods of digital assessment combined with traditional restorative philosophies to allow the clinician to plan implant positions based on "crown-down" clinical requirements. This approach permits clinicians to have more control over the implant treatment plan by creating ideal, virtual restorations and managing implant positions based on the virtual plan with simplified, cost-effective techniques.

Surgical templates for dental implant positioning; current knowledge and clinical perspectives

Dental implants have been used in a variety of different forms for many years. Since the mid-20^th century, there has been an increase in interest in the implant process for the replacement of missing teeth. Branemark was one of the initial pioneers who applied scientifically based research techniques to develop an endosseous implant that forms an immobile connection with bone. The need for a dental implant to completely address multiple physical and biological factors imposes tremendous constraints on the surgical and handling protocol. Metallic dental implants have been successfully used for decades, but they have serious shortcomings related to their bony union and the fact that their mechanical properties do not match those of bone. However, anatomic limitation and restorative demands encourage the surgeon to gain precision in planning and surgical positioning of dental implants. Ideal placement of the implant facilitates the establishment of favorable forces on the implants and the prosthetic component as well as ensures an aesthetic outcome. Therefore, it is advisable to establish a logical continuity between the planned restoration and the surgical phases, it is essential to use a transfer device that for sure increases the predictability of success. The surgical guide template is fabricated by a dental technician after the presurgical restorative appointments that primarily include determination of occlusal scheme and implant angulations. Here, authors genuinely attempted to review the evolution and clinical applicability of surgical templates used in the placement of dental implants.

Radiopaque dental impression method for radiographic interpretation, digital alignment, and surgical guide fabrication for dental implant placement

Adequate visualization of existing/proposed tooth position, denture base contours, and prosthetic space is critical to treatment planning of dental implants. Multiple techniques exist for fabricating radiographic guides; many involve duplicating the patient's existing prosthesis or fabricating a new diagnostic template. This article describes a technique that provides anatomic and restorative information by using an existing prosthesis and a radiographic impression method without the need to fabricate a duplicate or new template.

Types of Implant Surgical Guides in Dentistry: A Review

Various techniques have been proposed for the fabrication of surgical guide templates in implant dentistry. The objective of this paper is to review the associated literature and recent advancements in this field, based on design concept. An electronic and hand search of the literature revealed 3 categories, namely, nonlimiting, partially limiting, and completely limiting design. Most clinicians still adopt the partially limiting design due to its cost-effectiveness and credibility. Moreover, clinicians use cross-sectional imaging during the preimplant assessment of surgical sites.

Dimensional accuracy and details of the panoramic cross-sectional tomographic images: an in vitro study

INTRODUCTION

Transversal slicing system (TSS) of Planmeca PM 2002 CC is a tomographic technique which enables us to take cross-sectional views of jaws. Tomographic imaging modalities are commonly applied to acquire cross-sectional images of the jaws for preimplant assessment of bone. Among the available tomographic imaging modalities, panoramic radiography is the most accessible imaging system.

MATERIALS AND METHODS

Study was conducted using 25 mandibles, out of these five were used for linear dimensional accuracy measurement and the rest 20 were utilized to study the details within the mandible. Study was aimed to evaluate dimensional stability in the images using different parameters, such as determination of direction of slice, determination of horizontal and vertical magnification, angular distortion, three dimensional distortion and determination of details.

RESULTS

For the direction of slice and for determination of horizontal and vertical magnification change in + 5º to - 5º was in acceptable limit. In determination of details, it was found that there was great discrepancy in readings given by nonradiologist which offset the mean value which was attributed to lack of training for interpretation of the observers.

CONCLUSION

99% of the readings were in the clinically acceptable limits.

CLINICAL SIGNIFICANCE

The easy availability, use of routine equipment, the low cost, low radiation dose for cross-sectional radiography make the TSS most preferred modality.

Use of diagnostic and surgical stent: a simplified approach for implant placement

Dental implantology has emerged as a practical alternative to traditional prosthodontics. Since the beginning, placement of implant in the bone to achieve a prosthetic solution that fulfils biologic, aesthetic and biomechanical requirements has been a challenge. In the past, implant site and inclination were dictated by residual bone quality. The desire for predictable prosthesis led to the development of prosthetically guided implantology. This concept establishes the correct implant position during the diagnostic stage according to planned definitive restoration. In prosthetically guided implantology where ideal placement of implant is determined by the definitive restoration, use of radiographic and surgical stent in conjunction with dental CT scan can play an important role. A stent is an appliance used for radiographic evaluation during treatment planning for implant placement and during surgical procedures to locate optimal implant placement site. The stent with dental CT scan enables the dental team to identify specific sites of prospective implant surgery and hence determines the optimal position and angulation of implant relative to occlusal load. Aided by stent the surgeon can avoid undesirable implant site preparation and minimize unnecessary osteotomy, resulting in favorable design of prosthesis, reduced surgical trauma, reduced surgical time and increased patient comfort. This case report is an insight into the method of fabrication of simple and cost effective stent for implant placement and its advantages over the other techniques of stent fabrication.

A surgical stent for the Brånemark Novum bone reduction procedure

BACKGROUND

The Brånemark Novum concept (Nobel Biocare AB, Göteborg, Sweden) was introduced to load implants immediately with a definitive fixed prosthesis in the edentulous mandible. This concept is based on the use of prefabricated templates to allow precise placement of three implants and a prefabricated bar structure for the prosthetic procedure. To obtain three-dimensional stability in these prefabricated templates, surgical bone reduction may be necessary to obtain a stable adaptation between the templates and the recipient bone site.

PURPOSE

The aim of this work was to design a surgical stent for predictable reduction of the residual alveolar crest prior to the implant placement procedures.

MATERIALS AND METHODS

A predetermined alveolar crest platform based essentially on a lateral cephalometric radiographic evaluation was simulated on a cast in order to design a transparent resin surgical guide. The predictability potential of the procedure was then evaluated in 10 patients. The prosthetic outcomes were compared with those of a similar group of 10 patients treated without the presented stent by evaluating two factors, namely, the anterior dimensions of the prostheses and the required posterior adjustments of the upper bar.

RESULTS

Correlation analysis of our series suggested a good predictability potential for this procedure (r = 0.9215). The mean anterior prosthetic dimension was 32% lower and was more predictable (narrow range of 8-12 mm vs broad range of 8-21 mm) when the stent was used. Furthermore, since half as many posterior adjustments of the upper bar were required, the laboratory procedure was facilitated.

CONCLUSION

This individualized guide allows appropriate bone reduction for obtaining a predictable surgery and prosthetic stage.

A dual-purpose guide for optimum placement of dental implants

Correct placement of implants is a requirement for implant treatment. The use of computed tomography and precise surgical guides is required when inadequate bone support is anticipated. This article describes the fabrication and use of an acrylic resin dual-purpose guide for radiographic evaluation of recipient sites and implant placement, which uses internally stacked stainless steel surgical guide channels. The drill guides are machined to allow consecutive surgical drills to be used without changing the implant angulation during surgery.

Precision surgical template for implant placement: a new systematic approach

The importance of a precise surgical template for implant placement cannot be overstated. The radiographic template carries both clinical and radiographic information for the planning of fixture angulation and location. This article describes a systematic approach to the fabrication of a dual-purpose radiographic surgical template. The simple steps result in the accurate transfer of radiographic information to the surgical template with no need for complex equipment or maneuvers. key words: dental implants, implant placement, radiographic template, surgical template

A multifunctional, provisional, implant-retained fixed partial denture

This article describes the modification of a procedure for fabricating a laboratory-processed, metal-reinforced, acrylic resin provisional restoration that becomes an implant-retained fixed partial denture. The modification involves the incorporation of patrix and matrix components into a cast metal framework. The prosthesis can be used as an alternative to a removable radiologic stent and surgical guide. It can function as a surgical guide during implant placement and help retract the buccal mucogingival flap during implant placement. The prosthesis also can be used as an aid in locating the implant during stage II surgery. Finally, the pontics can be converted into an implant-supported provisional restoration immediately after the implant prosthetic components are attached to the uncovered implants.

Simplified radiographic-surgical template for placement of multiple, parallel implants

A radiographic-surgical template can facilitate consultation with a surgeon and patient when implant-supported restorations are planned. A template that provides radiographic evaluation of the implant site and precise or modified surgical placement is presented.

Bilaminar dual-purpose stent for placement of dental implants

Proper placement of implants in the posterior maxillary region with poor bone density is essential to obtain long-term success. In this article, the fabrication of a bilaminar dual-purpose stent that facilitates ease in implant placement with improved verification of implant positioning is described. The outer lamina is designed for use in the computed tomography evaluation, using radiopaque markers. The verification of implant alignment and positioning, according to the determined prosthesis, is also performed with this template after modifying it for surgery. The inner lamina is designed to accept 2 removable surgical acrylic resin stents with different guide channels that avoids the risk of surgical malpractice.