Site Of Implant Placement Research Articles

Monocytes

Monocytes are progenitor cells that lead the inflammatory cascade reaction responsible for guiding revascularization and regeneration of tissue at injury sites. They do this by secreting inductive cytokines responsible for endothelial cell migration. When released into the peripheral blood, monocytes enter tissues and become macrophages. Monocytes also trigger the body's defense mechanism against microbial invasion by lysing and removing cell debris and dead tissue. The aim of this article is to explain the role of monocytes in the processes of bone healing and regeneration and describe their interaction with stem cells and other entities. Results of a pilot histomorphometric study in which concentrated monocytes were combined with demineralized allograft material to augment implant-placement sites in 2 patients also are presented.

Maxillary sinus and mandibular canal location

Dental implants have taken over the role of third dentition in recent times. The success of dental implants depends on the accurate placement of these implants. Key structures for an implantologist are the maxillary sinus and the mandibular canal. Shahin and coworkers[1] have carried out an innovative study with regard to the position of the maxillary sinus and mandibular canal, using a linear tomographic radiograph. They have studied the radiographic distance of maxillary sinus floor and mandibular canal to the alveolar crest and correlated it with the stature of individuals in a specific South Indian population. Some professional organizations have set up their own recommendations for clinical and radiographic pre-implant evaluation.[2–4] Linear tomography was used to evaluate the position of important anatomical structures. When used with a panoramic view, linear tomography allows the clinician to determine the implant placement site in all three planes.[5] A study using linear tomography was also carried out in the Indian population.[6] The fact that makes this study interesting is the associated radiographic features with stature. As stated in the conclusion of the study, a larger sample size would be more conclusive and useful.

Avoiding traumatic injury to the tissues in the new millennium.

Dear Editor, While the world of surgery and medicine is racing towards endoscopic less invasive surgical techniques, we here are still quoting the 19th century adage “great surgeons make great incisions”. I teach oral and maxillofacial surgery at both undergraduate and postgraduate levels and can attest to the fact that minimally invasive procedures can maximize patient comfort by avoiding traumatic injury to the tissues. For example in my field, treatment modalities for plating of orbital and condylar fractures, antral explorations etc. have been done less traumatically using endoscopic surgery. In other fields, bronchoscopic procedures, laparoscopic removal of tissues, transurethral approaches to enlarged prostate etc. are being used indicative of a rapid shift towards less aggressive, noninvasive methods gaining acceptance. The role of diagnosis technology and computer-aided surgery is very relevant, and magnification technology with the assistance of computer technology, work together to provide more precise treatments offering patients a less traumatic experience. The technology of computerized navigation has been developed in medicine for brain, ENT and orthopedic surgery. We have borrowed the concept of minimally invasive surgery (MIS) from other medical fields, as it has its greatest implications in the field of maxillofacial surgery. MIS involves smaller and more accurate incisions, using magnification systems and microsurgery instruments. MIS also requires fewer operations, which implies a very precise planning and a combination of surgical techniques aiming at several objectives simultaneously. In my field, ideal positioning of dental implants makes use of three-dimensional orientation technology to define accurately the mandibular canal or maxillary sinus, zygoma and pterygoid implant placement sites, roots of neighboring teeth as well as the optimum esthetic location to place the implant. Flapless insertion of dental implants can prevent complications arising from soft-tissue elevation such as infection, dehiscence and necrosis, and provides dental implant success rates equal to conventional techniques (1). In the anterior mandible, the flapless technique requires surgical guidance for optimal tilt of drilling to avoid injury to underlying anatomical structures during preparation of the implant socket. Computer-assisted surgery is known to enhance safety in dental implantology while being compatible with all aspects of implant surgery including flapless techniques (2). Flapless implant surgery has improved both the osseointegration of dental implants and the bone height around implants. Many investigators have emphasized that flapless implant surgery is a predictable procedure with high success rates if patients are appropriately selected and an appropriate width of bone is available for implant placement. The preservation of bone vascularization when no flaps are reflected may help optimize bone regeneration around implants.As it is now believed by some authors that flapless placement of implants cannot be successfully fulfilled in all the regions of the jaw bones, taking advantage of the new 3-D computerized navigation technologies, will certainly add to state-of-the art surgery.

Immediate Placement and Provisionalization With Buccal Plate Preservation: A Case Report of a New Technique

Abstract Abstract Post-extraction resorption of the alveolar ridge is known particularly to affect the buccal plate, increasing the risk of facial soft-tissue recession and other adverse clinical effects. The authors have developed a simple technique for buccal plate preservation that involves surgically creating a pouch facial to the buccal plate that is filled with xenograft material. This technique can also be utilized in cases for which immediate implant placement and provisionalization are planned. A case report illustrating this approach is presented.

Crestal Sinus Lift With Sequential Drills and Simultaneous Implant Placement in Sites With <5 mm of Native Bone: A Multicenter Retrospective Study

The aim of this multicenter retrospective clinical study was to evaluate the survival rate of implants placed in the posterior maxilla with a residual bone height of <5 mm. One hundred seventeen patients, recruited from 6 different centers, had 134 implants placed below the maxillary sinus. The patient population consisted of 52 men and 65 women ranging in age from 39 to 78 years (mean age, 53.2 years). Sinus lift procedures were performed following a crestal approach using a specific sequence of drills (Cosci's technique). All implants were submerged. Periapical radiographs were obtained with a paralleling technique and were digitized. The pattern of bone remodeling was subsequently evaluated. The average (±SD) follow-up time was 48.2 months (±29.30 months; range, 24 to 120 months). Of the original 134 implants placed, 5 implants (3.7%) failed. The implant survival rate was 96.3%. The average residual bone height was 3.46 mm (±0.91 mm) at baseline. The average height of the alveolar crest in the treated implant sites was 9.94 ± 2.29 mm. The radiographic bone gain was 6.48 ± 2.38 mm. The investigation suggests that this crestal drill approach can be a successful sinus lifting procedure in a severe atrophic maxilla with <5 mm of crestal bone height.

Cortical bone thickness at common miniscrew implant placement sites

The purpose of this study was to assess age, sex, and regional differences in the cortical bone thickness of commonly used maxillary and mandibular miniscrew implant placement sites. Cone-beam computed tomography images, taken at 0.39-mm voxel size, of 52 patients, including 26 adolescents (13 girls, ages 11-13; 13 boys, ages 14-16) and 26 adults (13 men and 13 women, ages 20-45), were evaluated. The cone-beam computed tomography data were imported into 3-dimensional software (version 10.5, Dolphin Imaging Systems, Chatsworth, Calif); standardized orientations were used to measure cortical bone thickness at 16 sites representing the following regions: 3 paramedian palate sites, 1 infrazygomatic crest site, 4 buccal interradicular sites of the mandible, and 4 buccal and 4 lingual interradicular sites in the maxilla. Multivariate analysis of variance (MANOVA) showed no significant differences in cortical bone thickness between the sexes. There were significant (P<0.05) differences between adolescents and adults, with adult cortices significantly thicker in all areas except the infrazygomatic crest, the mandibular buccal first molar-second molar site, and the posterior palate site. Cortical bone was thicker in the posterior than in the anterior mandibular sites. In the adults, interradicular bone in the maxillary first premolar-second premolar, and second premolar-first molar sites was thicker than bone at the lateral incisor-canine and first molar-second molar sites. Anterior paramedian palatal bone was significantly thicker than bone located more posteriorly. The mandibular buccal and infrazygomatic crest regions had the thickest cortical bone; differences between the maxillary buccal, the maxillary lingual, and the palatal regions were small. Maxillary and mandibular cortical bones at commonly used miniscrew implant placement sites are thicker in adults than in adolescents. There are also differences in cortical bone thickness between and within regions of the jaws that must be considered when placing miniscrew implants.

Immunohistochemical characteristics of the Implant-Hosted Bon: Preliminary findings of 9 mandibular cores

The aims of this study were to investigate the biochemical topography of collagen types I and III and to describe the histological structure at the implant placement site to determine the clinical significance of the findings and their possible interaction with bone healing around dental implants. Bone cores from 9 mandibles were taken from the site of placement of dental implants. The reliable technique for rapid preparation of fresh-frozen undecalcified bone sections and the indirect immunofluorescent technique as an immunohistochemical procedure were applied. All sections were viewed under U.V light. For comparative purposes the tissue blocks remaining were used for general histology examination. A homogenous distribution of collagen type I throughout the sections of all cores was evident. Whereas, the distribution of collagen type III throughout the sections of all cores was heterogeneous with different staining patterns. On the other hand, seven cores of the general histology study showed a structure of lamellar mature bone and two cores showed a structure of less mature woven bone. The biochemical and histological structures of the hosted bone may have an impact on the speed of bone healing around dental implants.

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.

Effects of Early Functional Loading on Maintenance of Free Autogenous Bone Graft and Implant Osseointegration: An Experimental Study in Dogs

The aim of the present study was to investigate the healing, integration, and maintenance of autogenous onlay bone grafts and implant osseointegration either loaded in the early or the delayed stages. A total of 5 male dogs received bilateral blocks of onlay bone grafts harvested from the contralateral alveolar ridge of the mandible. On one side, the bone block was secured by 3 dental implants (3.5 mm x 13.0 mm, Osseospeed; AstraTech AB, Mölndal, Sweden). Two implants at the extremities of the graft were loaded 2 days after installation by abutment connection and prosthesis (simultaneous implant placement group); the implant in the middle remained unloaded and served as the control. On the other side, the block was fixed with 2 fixation screws inserted in the extremities of the graft. Four weeks later, the fixation screws were replaced with 3 dental implants. The loading procedure (delayed implant placement group) was performed 2 days later, as described for the simultaneous implant placement sites. The animals were sacrificed 12 weeks after the grafting procedure. Implant stability was measured through resonance frequency analysis. The bone volume and density were assessed on computed tomography. The bone to implant contact and bone area in a region of interest were evaluated on histologic slides. The implant stability quotient showed statistical significance in favor of the delayed loaded grafts (P = .001). The bone-to-implant contact (P = .008) and bone area in a region of interest (P = 0.005) were significantly greater in the delayed group. Nevertheless, no difference was found in terms of graft volume and density between the early loaded and delayed-loaded approaches. The protocol in which the implant and bone graft were given delayed loading allows for effective quality of implant osseointegration and stabilization, with healing and remodeling occurring in areas near the implant resulting in denser bone architecture.

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Thick vs. Thin Gingival Biotypes: A Key Determinant in Treatment Planning for Dental Implants

During the treatment planning process, it is important to recognize differences in gingival tissue can affect treatment outcomes. The concept that thick and thin gingival biotypes have different responses to inflammation and trauma was previously introduced. In this paper, this concept is expanded in that gingival biotypes dictate different procedures for implant site preparation. With appreciation of these differences, preparatory steps can be taken to create a more ideal implant placement site.

Histological evaluation on bone regeneration of dental implant placement sites grafted with a self‐setting α‐tricalcium phosphate cement

This study aimed to evaluate the histological characteristics of the new bone formed at dental implant placement sites concomitantly grafted with a self-setting tricalcium phosphate cement (BIOPEX-R). Standardized defects were created adjacent to the implants in maxillae of 4-week-old male Wistar rats, and were concomitantly filled with BIOPEX-R. Osteogenesis was examined in two sites of extreme clinical relevance: (1) the BIOPEX-R-grafted surface corresponding to the previous alveolar ridge (alveolar ridge area), and (2) the interface between the grafting material and implants (interface area). At the alveolar ridge area, many tartrate-resistant acid phosphatase (TRAPase)-reactive osteoclasts had accumulated on the BIOPEX-R surface and were shown to migrate toward the implant. After that, alkaline phosphatase (ALPase)-positive osteoblasts deposited new bone matrix, demonstrating their coupling with osteoclasts. On the other hand, the interface area showed several osteoclasts initially invading the narrow gap between the implant and graft material. Again, ALPase-positive osteoblasts were shown to couple with osteoclasts, having deposited new bone matrix after bone resorption. Transmission electron microscopic observations revealed direct contact between the implant and the new bone at the interface area, although few thin cells could still be identified. At both the alveolar ridge and the interface areas, newly formed bone resembled compact bone histologically. Also, concentrations of Ca, P, and Mg were much alike with those of the preexistent cortical bone. In summary, when dental implant placement and grafting with BIOPEX-R are done concomitantly, the result is a new bone that resembles compact bone, an ideal achievement in reconstructive procedures for dental implantology.

Evaluation of sinus floor elevation using a composite bone graft mixture

The performance of implant surgery in the posterior maxilla often poses a challenge due to insufficient available bone. Sinus floor elevation was developed to increase needed vertical height to overcome this problem. The present study described and reported a simple, safe and predictable bone graft mixture for the sinus lifting procedure. Seventy patients were recruited for this study and underwent a sinus lift procedure. All sites were treated with a composite graft of cortical autogenous bone, bovine bone and platelet-rich plasma (PRP). A total of 263 implants (171 Astra Tech and 92 Microdent) were placed either simultaneously or delayed. All sites were clinically and radiographically evaluated 24 months after their prosthetic loading. Biopsy samples were taken from 16 delayed implant placement sites at the time of their implant placement. A 100% implant success rate was found after 24 months of functioning. Only two Microdent implants failed before loading, which translates to a 99% overall implant success rate. No statistically significant differences were found between simultaneous and delayed implant placement. Image processing revealed 34+/-6.34% vital bone, 49.6+/-6.04% connective tissue and 16.4+/-3.23% remaining Bio-Oss particles. However, the histomorphometric analysis showed that the bovine bone was incorporated into new bone formation. The results showed that a composite graft comprised of cortical autogenous bone, bovine bone and PRP mixture can be successfully used for sinus augmentation.

Pre-operative Drilling Simulation Method for Dental Implant Treatment

The position, depth and direction of implant placement are often planned based on evaluation of radiographs and study casts. Insertion planned in such a manner may not be adequate for precise and safe surgery in some cases due to inadequate working clearance in the oral cavity. In order to obtain high initial stability and ensure osseointegration at the implant-bone interface, careful and precise drilling must be performed at the implant placement site. Therefore, we propose the necessity of evaluating the operability of implant treatment-devices prior to surgery. The amount of handling space needed during implant placement surgery was determined. The results showed that for implants with a length of 7-18 mm, a vertical distance of as much as 50-60 mm was required, depending on the implant platform. These results suggest the necessity of pre-operative drilling simulation in each individual. Handling space was measured with angled heads and probes fabricated on a trial basis for pre-surgical drilling simulation in the oral cavity. We believe that these instruments may be clinically useful in estimating the amount of handling space required prior to surgery and ensuring precise implant placement. Evaluation of the intra-oral environment for handling of treatment devices should be included in the pre-surgical intra-oral evaluation of dental implant cases to avoid changes in treatment planning due to intra-oral interference during the course of surgery.

Biomechanical aspects of initial intraosseous stability and implant design: a quantitative micro‐morphometric analysis

The objective of this biomechanical study was to explore the effect of bone micro-morphology on initial intraosseous stability of implants with different designs. Straumann and Astra Tech dental implants were placed into anterior and posterior regions of completely edentulous maxilla and mandible of a human cadaver. Experiments were undertaken to quantify initial implant stability and bone micro-morphology. Installation torque values (ITVs) and implant stability quotients (ISQs) were measured to determine initial intraosseous implant stability. For quantification of relative bone volume and micro-architecture, sectioned implant-bone and bone core specimens of each implant placement site were consecutively scanned and trabecular bone was analyzed in a micro-computed tomography (micro-CT) unit. Experimental outcomes were evaluated for correlations among implant designs, initial intraosseous implant stability and bone micro-structural parameters. ITVs correlated higher with bone volume fraction (BV/TV) than ISQs, at 88.1% and 68.9% levels, respectively. Correlations between ITVs and micro-morphometric parameters were significant at the 95% confidence level (P<0.05) while ISQs were not. Differences in ITVs, ISQs and BV/TV data in regards to implant designs used were not significant at the 95% confidence level (P>0.05). Bone micro-morphology has a prevailing effect over implant design on intraosseus initial implant stability, and ITV is more sensitive in terms of revealing biomechanical properties at the bone-implant interface in comparison with ISQ.

Tissue Engineering for Periodontal Regeneration

As a result of periodontal regeneration research, a series of clinical techniques have emerged that permit tissue engineering to be performed for more efficient regeneration and repair of periodontal defects and improved implant site development. Historically, periodontal regeneration research has focused on a quest for "magic filler" material. This search has led to the development of techniques utilizing autologous bone and bone marrow, allografts, xenografts, and various man-made bone substitutes. Though these techniques have had limited success, the desire for a more effective regenerative approach has resulted in the development of tissue engineering techniques. Tissue engineering is a relatively new field of reconstructive biology which utilizes mechanical, cellular, or biologic mediators to facilitate reconstruction/regeneration of a particular tissue. In periodontology, the concept of tissue engineering had its beginnings with guided tissue regeneration, a mechanical approach utilizing nonresorbable membranes to obtain regeneration in defects. In dental implantology, guided bone regeneration membranes +/- mechanical support are used for bone augmentation of proposed implant placement sites. With the availability of partially purified protein mixture from developing teeth and growth factors from recombinant technology, a new era of tissue engineering whereby biologic mediators can be used for periodontal regeneration. The advantage of recombinant growth factors is this tissue engineering device is consistent in its regenerative capacity, and variations in regenerative response are due to individual healing response and/or poor surgical techniques. In this article, the authors review how tissue engineering has advanced and discuss its impact on the clinical management of both periodontal and osseous defects in preparation for implant placement. An understanding of these new tissue engineering techniques is essential for comprehending today's ever-expanding oral plastic surgery procedures.

Immediate implants covered with connective tissue membranes: human biopsies.

Osseointegration has been shown to occur around implants placed immediately after tooth extraction in humans. To date, such osseointegration has been achieved only with titanium plasma-sprayed (TPS) implants placed in extraction sockets with a bone-to-implant distance of less than 2 mm. In a previous report, when this horizontal defect dimension (HDD) exceeded 2 mm, the resulting percentage of bone-to-implant contact was reduced, indicating that the immediate technique would be limited in most cases to non-molar teeth. In an attempt to improve the bone-to-implant contact and the initial bone-to-implant contact in a vertical dimension, the implant surface, the type of membrane, and the method of membrane placement used in a previous study by our group were modified. Ten large-grit sandblasted, acid-attacked (SLA) titanium implants were placed into immediate extraction sites in 5 patients. HDDs of 0.0 to 1.5 mm (controls), 1.5 to 4.0 mm, and >4.0 mm were used. Following insertion, implants were completely covered with a connective tissue membrane. This was in contrast to the use of an expanded polytetrafluoroethylene (ePTFE) membrane penetrated by the neck of the implant in our previous report. Primary closure of soft tissue flaps was achieved in each case. Six months after placement, 7 of the implants were histologically examined. Osseointegration occurred across all HDDs, with the percentage of bone-to-implant contact in the 0.0 to 1.5 mm HDDs similar to that seen in the >4.0 mm HDDs. The first bone-to-implant contact measured vertically was similar in both the smaller and larger HDDs. Osseointegration was successful in immediate implant placement sites with horizontal defect dimensions wider than 4 mm in humans when SLA titanium implants were completely covered with connective tissue membranes. It remains undetermined whether the different type of membrane, placement of the membrane, type of implant surface, or a combination of these 3 factors were responsible for the improved osseointegration in HDDs >4 mm. Further study is needed.