Surgical template for completely edentulous patients

Implant angulation is of utmost importance for fabrication of esthetic, hygienic, and functional prostheses, even in the treatment of completely edentulous patients. Most mandibular surgical templates are not reliable because of a lack of stability resulting either from severe resorption of the mandible or from the interference of mucoperiosteal flaps elevated during surgery. This article describes a technique for fabrication and surgical application of a stable template for the completely edentulous mandible. By combining the mandibular template with a maxillary duplicate denture, the problem of lack of stability can be overcome. A consistently reliable reference for implant placement in the edentulous mandible, specifically in relation to implant angulation (trajectory), can be obtained.     

The UCLA abutment: a four-year review.

The UCLA abutment has been used over the past 4 years in the restoration of osseointegrated implants. The design of the abutment allows fabrication of the restoration directly to the implant fixture, bypassing the transmucosal abutment cylinder. This technique is valuable in overcoming problems of limited interocclusal distance, interproximal distance, implant angulation, and soft tissue response. Another major advantage with the UCLA abutment is that of improved esthetics. After treatment of 46 patients with 118 UCLA abutments, the 4-year success rates are 95.8%.     

Templates as an aid in implantology

The number, position and angulation of implants are of major importance in loading of implants and surrounding bone and in esthetics. Especially in single tooth and partially edentulous cases correct positioning of implants takes a great deal of care. A template is a device that helps to achieve the proper amount of bone and the correct position and angulation of implants. The design and fabrication of radiographic templates, diagnostic templates and surgical templates are described, both in general and specifically for overdentures and non-removable implant-supported restorations.     

Fabrication of imaging and surgical guides for dental implants

Research and experience have suggested that the success of dental implants depends on a well-developed and careful treatment plan approach. Historically, implant size and angulation were determined with the use of panoramic radiographs and clinical judgment during surgery. This occasionally resulted in mechanical and esthetic compromise. This article describes the step-by-step fabrication process for 4 different imaging and surgical guides. Set-up disks, which enhance the design and fabrication of guides, also are introduced. These guides are used in conjunction with cross-sectional tomography during the preimplant assessment of surgical sites.     

A simple three-dimensional stent for proper placement of mini-implant

Background

This paper deals with the fabrication of a three-dimensional stent which is simple in design but provides an accurate placement of a mini-implant in three planes of space, namely, sagittal (root proximity), vertical (attached gingiva/alveolar mucosa) and transverse (angulation).

Findings

The stent is made of 0.018 × 0.025 in. stainless steel archwire which consists of a ‘u loop’ angulated at 20°, a vertical limb, a horizontal limb and a stop. The angulation of the ‘u’ helps in the placement of the mini-implant at 70° to the long axis of the tooth. The vertical height is determined such that the mini-implant is placed at the mucogingival junction. The mini-implant is placed with the aid of the stent, and its angulation and proximity to the adjacent roots are checked with a cone beam computed tomography image. The cone beam computed tomography image showed the mini-implant at an angle of 70° to the long axis of the tooth. There is no contact between mini-implant and the roots of the adjacent teeth.

Conclusion

This stent is simple, easy to fabricate, cost-effective, and provides ease of insertion/removal, and three-dimensional orientation of the mini-implant.     

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     

Mesiodistal root angulation of permanent teeth in children with mixed dentition and normal occlusion

Objective

There is little information regarding the mesiodistal angulation of permanent teeth in mixed dentition. The aim of this study was to evaluate mesiodistal root angulation of permanent incisors, canines and first molars of 100 Brazilian children, using a new horizontal reference plane based on the midpoint of the intercuspation of primary canines and permanent first molars in panoramic radiographs during the mixed-dentition phase.

Material and methods

Children were equally divided between the genders with a mean age of 8.9 years (SD=0.76), normal occlusion and no eruptive disturbances.

Results

The angulation of the permanent maxillary first molars was close to the vertical, whereas the mandibular molars presented approximately 25 degrees of distal root angulation. The maxillary canines were the most distally angulated teeth, whereas the permanent mandibular canines were vertically positioned. The evaluation of the anterior maxillary area showed vertical position of permanent lateral, and central incisors with a slight distal angulation, whereas the permanent mandibular incisors tended to a mesial radicular convergence.

Conclusions

The proposed reference line could be useful in mixed dentition root angulation evaluation; there was a slight asymmetry in the mesiodistal angulation among homologous teeth, and also a small variation between the male and the female groups, but no difference between 8-and 10-year-old children.     

Influence of projection angles upon position of cementoenamel junction on radiographs

The CEJ on radiographs is often used as a reference point in the assessment of alveolar bone loss. The aim of the present study was to test the stability of the radiographic CEJ ("RCEJ") in relation to the alveolar crest under varying angulations of the central X-ray beam. In an experimental model four types of extracted teeth were radiographed at 0 degree and 20 degrees vertical angulation and at 15 horizontal angulations varying from a 17.5 degrees mesial view to a 17.5 degrees distal view. The buccal alveolar bone margin was simulated by a steel needle. RCEJ-"crest" distances were read at a X 10 magnification. Changing the vertical angulation from 0 degree to 20 degrees reduced the RCEJ-"crest" distances for all tooth types (range of average reduction 2.2-4.1 mm). Horizontal angulations without concomitant vertical angulation had a significant effect but were without clinical significance. Horizontal angulations in combination with a 20 degrees vertical angulation had a considerable influence; in a mesial view, mesial RCEJ-"crest" distances decreased and distal ones increased, and vice versa in a distal view. The deviations from the true CEJ-crest distance demonstrated may be of clinical significance, and a critical attitude to alveolar bone loss measures on radiographs using the RCEJ as reference point is recommended.     

Celebrity smile esthetics assessment: Smile angulation

Statement of problem

Whether deviations in the angulation discrepancy between the intercanine and interpupillary line significantly affect attractiveness is unknown.

Correction of Deviation of a Partially Resected Mandible Using a Palatal Ramp with the Aid of a Semi‐Adjustable Articulator

Patients having undergone hemi‐mandibulectomy without further reconstruction (to restore the lost mandibular continuity) suffer functional limitations due to the resultant deviation of the segmental mandible. A palatally based guidance prosthesis (or palatal ramp prosthesis) is often indicated and is usually fabricated chairside in self‐cured acrylic resin. Establishing the correct angulation of the slope of the palatal ramp may take several attempts before a satisfactory correction is achieved. This clinical report describes a laboratory technique in which a semi‐adjustable articulator was used for fabricating the palatal ramp prosthesis. The patient's deviated mandibular position was transferred to the articulator by means of a facebow and interocclusal record. The angulation of the palatal ramp was then established on the semi‐adjustable articulator and the prosthesis fabricated in heat‐cured acrylic resin. Reduced chairside time, improved patient comfort levels, and ease in fabrication of the prosthesis on the semi‐adjustable articulator are proposed advantages of the described technique.     

A New Surgical Template with a Handpiece Positioner for Use During Flapless Placement of Four Dental Implants to Retain a Mandibular Overdenture

This article describes the fabrication of a new and inexpensive surgical template from a radiographic template for flapless placement of dental implants to retain a mandibular overdenture. A radiographic template with radiopaque metal plate markers is constructed and used as a guide for achieving three‐dimensional evaluation of bone using computed tomography (CT). The potential position and angulation of the implants are measured relative to the metal plates using the CT data. The radiographic template is converted into a surgical template by attaching rigid metal rods that guide the handpiece precisely during subsequent drilling procedures.     

Use of Stereolithographic Templates for Surgical and Prosthodontic Implant Planning and Placement. Part I. The Concept

Surgical and prosthodontic implant complications are often an inadvertent sequelae of improper diagnosis, planning, and placement. These complications pose a significant challenge in implant dentistry. Presented in this article is a technique using a highly advanced software program along with a rapid prototyping technology called stereolithography. It permits graphic and complex 3D implant simulation and the fabrication of computer-generated surgical templates. These templates seat directly on the bone and are preprogrammed with the individual depth, angulation, and mesio-distal and bucco-lingual positioning of individual implants as planned during the 3D computer simulation.     

A Systematic Approach to Definitive Planning and Designing Single and Multiple Unit Implant Abutments

With an increase in the availability of implant restorative components, the selection of an appropriate implant abutment for a given clinical situation has become more challenging. This article describes a systematic protocol to help the practitioner more thoughtfully select abutments for single and multiple unit fixed implant prostheses. The article examines the evaluation, planning, design, and fabrication processes for the definitive restoration. It includes an assessment of a variety of factors, namely restorative space, soft and hard tissues, the location of the implant platform, the type of platform connection, platform switching indications, tissue collar heights, emergence profile, implant angulation, and finally the design and esthetic options for the final implant abutment.     

Ideal gingival form with computer-generated permanent healing abutments

Implant fixture positioning and inclination problems that result from poor osseous height, width, and ridge configuration have created difficult prosthetic tooth replacement scenarios. Options for ameliorating poor angulation are limited to the use of preangled and custom abutments. Overcoming poor angulation has been simplified by using custom vs preangled abutments because preangled abutments are limited by their standardization to a few random angles. Custom abutments can be more predictably formed to re-create the desired supporting preparation orientation and morphology. This facilitates the formation of anatomical gingival topography and coronal contours for prosthetic replacement. Cast, ceramic, and machine-milled titanium abutments have several advantages and disadvantages. A new custom abutment system that uses computer-guided manufacturing technology to machine mill custom abutments from commercially pure titanium is described. These abutments are anatomically correct, have the proper emergence anatomy, proper spatial design at the cervical margins, necessary occlusal reduction, and the proper axial angulation of ideal tooth preparations. A clinical case that illustrates implementation, with respect to the principle of stage 2 guided tissue healing, is presented.     

Estimation of angulation of Brånemark titanium fixtures from radiographic thread images

Identity of film positioning and of X-ray beam angulation is essential for valid comparisons of marginal bone height around osseointegrated implants. The purpose of the present study was to analyze the possibilities of estimating fixture angulation in relation to film plane from the threads of Brånemark fixtures. 10 observers compared 62 images of fixtures with angulations ranging from 0" to ± 15" with a set of reference radiographs. Out of 620 recordings, 29% were right, and 71% differed by ≥ 1". The observers distinguished with great accuracy between negative and positive angulations. 81% of the recordings differed by 2" or less. It is concluded that the threads of Brånemark fixtures are helpful in controlling the identity of serial radiographs of implants. The test circumstances were ideal compared to clinical cases, and it is possible that accuracy will be less in patient cases.     

Effect of Camera Angulation on Adaptation of CAD/CAM Restorations

Purpose: A significant concern with computer-assisted design/computer-assisted manufacturing (CAD/CAM)-produced prostheses is the accuracy of adaptation of the restoration to the preparation. The objective of this study is to determine the effect of operator-controlled camera misalignment on restoration adaptation.
Materials and Methods: A CEREC 2 CAD/CAM unit (Sirona Dental Systems, Bensheim, Germany) was used to capture the optical impressions and machine the restorations. A Class I preparation was used as the standard preparation for optical impressions. Camera angles along the mesio-distal and buccolingual alignment were varied from the ideal orientation. Occlusal marginal gaps and sample height, width, and length were measured and compared to preparation dimensions. For clinical correlation, clinicians were asked to take optical impressions of mesio-occlusal preparations (Class II) on all four second molar sites, using a patient simulator. On the adjacent first molar occlusal surfaces, a preparation was machined such that camera angulation could be calculated from information taken from the optical impression. Degree of tilt and plane of tilt were compared to the optimum camera positions for those preparations.
Results: One-way analysis of variance and Dunnett C post hoc testing (α= 0.01) revealed little significant degradation in fit with camera angulation. Only the apical length fit was significantly degraded by excessive angulation. The CEREC 2 CAD/CAM system was found to be relatively insensitive to operator-induced errors attributable to camera misalignments of less than 5 degrees in either the buccolingual or the mesiodistal plane. The average camera tilt error generated by clinicians for all sites was 1.98 ± 1.17 degrees.
CLINICAL SIGNIFICANCE
It is unlikely that camera misalignment is a major source of error during the fabrication of simplistic CEREC 2 CAD/CAM restorations.     

骨组织工程3D生物打印的研究进展

近几十年来,骨组织工程在骨缺损修复治疗的应用中获得了飞速的发展,而3D生物打印是近十年来在骨组织工程中一种非常具有前景的技术。传统骨组织工程支架制造方法无法精确控制空间结构,且在支架制作完成后接种细胞也无法控制细胞的均匀分布。尽管3D生物打印作为一类含细胞骨组织工程支架制造技术,以水凝胶类材料作为基础将细胞置入支架中,已经解决了上述问题,但一直以来其仍面临许多挑战,例如保持打印后的细胞活力、机械强度不足、成骨能力以及最主要的——血管化。近几年已经有许多研究通过改进生物墨水和打印方法以改善这些问题。本文介绍了骨组织工程的3D生物打印常用的技术和生物墨水,并对目前3D生物打印骨组织工程支架面临的挑战的一些研究进展进行了综述。通过中国期刊全文数据库(CNKI、万方)、PubMed数据库,检索2008年至2020年10月的相关文献,检索英文关键词为"3D bioprinting;cell-laden 3D printing;bone tissue engineering;bioink",中文关键词为"3D生物打印,骨组织工程",最终纳入57篇文献进行综述。     

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.     

Evaluation of the effect of the residual bone angulation on implant-supported fixed prostheses in mandibular posterior edentulism. Part I: Spiral computed tomography study

Dental implants are usually angulated buccolingually because of the anatomy of the residual bone in mandibular posterior edentulous cases. Although angulated dental implants compromise the construction of implant-supported prostheses, the effect of buccolingual angulation of the residual bone has not been clearly stated. This study is performed to determine the biomechanical effect of buccolingual angulation. The goal was to reveal the actual buccolingual angulation values of the residual bone in which implants were to be placed. Thirty mandibular Kennedy I and II cases comprised of forty edentulous posterior regions with missing second premolars and first, second, and third molars were included. Buccolingual angulation values along the 28 mm of residual bone were measured on 1-mm spacing cross-sectional images of spiral computed tomography. Paired sample t test was used for the statistical analysis. The minimum angulation values at the second premolar, first molar, and second molar region were 0 degrees, 3 degrees, and 9 degrees, respectively. The average angulation values were 4 degrees, 10 degrees, and 15 degrees, respectively, and the maximum angulation values were 11 degrees, 18 degrees, and 22 degrees, respectively. The ability to measure the buccolingual angulation of mandibular posterior residual bone before dental implantation may help the clinician at the implant treatment-planning phase.