Comparison of bone resorption at one-step and two-step mandibular endosseous implants in dogs

Endosseous dental implants have been inserted into dog jaw bone following two different implantation principles. Using the two-step procedure, the implant is left submerged, covered by the mucoperiosteum for a healing period, before communication with the oral cavity is established. According to the one-step procedure, this communication is established peroperatively. In order to estimate radiographically the degree of bone resorption following the two-step as compared to the one-step procedure, the former was used on the right and the latter on the left side of the mandible in two dogs. Periodic identical intraoral radiographs revealed bone resorption in the neck area of all implants. After a 1-yr period with bilateral bridges, the vertical resorption varied between 3 and 5 mm. No difference was found between the two methods concerning this bone resorption. The observation seems to be contrary to the general opinion on the matter, and pertinent investigations with the present model will be performed in a human material.     

Comparison of bone resorption at one-step and two-step mandibular endosseous implants in dogs

Abstract – Endosseous dental implants have been inserted into dog jaw bone following two different implantation principles. Using the two-step procedure, the implant is left submerged, covered by the mucoperiosteum for a healing period, before communication with the oral cavity is established. According to the one-step procedure, this communication is established peroperativcly. In order to estimate radiographically the degree of bone resorption following the two-step as compared to the one-step procedure, the former was used on the right and the latter on the left side of the mandible in two dogs. Periodic identical intraoral radiographs revealed bone resorption in the neck area of all implants. After a 1-yr period with bilateral bridges, the vertical resorption varied between 3 and 5 mm. No difference was found between the two methods concerning this bone resorption. The observation seems to be contrary to the general opinion on the matter, and pertinent investigations with the present model will be performed in a human material.     

Materials for endosseous dental implants

summary The goal of placement of endosseous dental implants is to achieve osseointegration or biointegration of the bone with the implant. A wide variety of materials has been used for these implants, but only a few promote osseointegration and biointegration. Titanium and titanium alloy (TJ6A14V) have been the most widely used of these materials. The surface oxide of titanium appears to be central to the ability of this material to osseointegrate. The oxide limits dissolution of elements and promotes the deposition of biological molecules which allow bone to exist as close as 30 å to the surface of the implant. The details of the ultrastructure of the gap between the implant and bone remain undefined, and the consequences of elements which are released on the interface over time are not known. These areas of investigation are particularly important in defining the differences between commercially pure titanium implants and those made of titanium, aluminium and vanadium. The epithelial interface between the gingiva and titanium appears to contain many of the structural characteristics of the native tooth-gingiva interface, but details are still vague. The connective tissue interface with the titanium appears to be one of tightly fitting tissues rather than adhesion. Ceramic coatings appear to improve the ingrowth of bone and promote chemical integration of the implant with the bone. The characteristics of these coatings are complex and affect the bony response, but the mechanisms remain obscure. The degradation of the coatings is an issue of particular controversy. Progress in dental implantology is likely to continue as the interface between the material and bone is more clearly understood, and biological molecules and artificial tissues are developed.     

Smoking and complications of endosseous dental implants

BACKGROUND: The purpose of this study was to compare the incidence of the complications and survival rate related to dental implants among smokers and non-smokers, and to evaluate the influence of smoking by analyzing data of 959 implants placed in 261 patients during the years 1995 to 1998. METHODS: Patients were divided into 3 groups: non-smokers, mild smokers (up to 10 cigarettes per day) and heavy smokers (more than 10 cigarettes per day); smokers were divided into 2 subgroups according to duration of smoking (less or more than 10 years). Complications included minor (spontaneous implant exposure), major (spontaneous implant exposure requiring surgical intervention), and implant failure. The influence of smoking was analyzed for the type of implant cover screw and immediate versus late implantation. RESULTS: The overall failure rate was 2% for non-smokers and 4% for all smokers. Minor and major complications were found in higher percentages (46%) in the smoking groups than in the non-smoking group (31%). A significantly higher incidence of complications was found among smokers who received dental implants with high cover screws (63%) compared to those who received dental implants with flat cover screws (27%). CONCLUSIONS: This study establishes a relationship between implant complications and smoking, implant type (external or internal hex), and time of implantation as significant factors. A higher incidence of complications was found in the smoking group, especially in implants that had a high cover screw. Most complications will not lead to failures. Immediate implants failed less frequently than non-immediate implants. Limiting or reducing smoking habits will decrease complications of endosseous dental implants.     

Histomorphometry of bone apposition around three types of endosseous dental implants.

Three different types of commercially available dental implants (Nobelpharma, IMZ, and Integral) were implanted in the edentulous mandibles of seven adult mongrel dogs. Twenty-one implants were harvested with block sections after 12 weeks and embedded in polymethyl methacrylate resin. Undecalcified sections were prepared with the sectioning-grinding technique. The percentage of bone contacting the implant surface was measured with a self-designed histomorphometry method using a millimeter grid in a stereomicroscope. The results demonstrated a significantly higher percentage of bone along the hydroxyapatite-coated implant than that seen with the titanium-surfaced implant types.     

Recombinant human bone morphogenetic protein-2 stimulation of bone formation around endosseous dental implants

BACKGROUND: Successful endosseous implant placement requires that the implant be stable in alveolar bone. In certain cases, the implant can be stabilized in native bone but some part of the implant is not covered by bone tissue. This often occurs during placement of implants into extraction sites or in areas where bone resorption has occurred and the ridge width is not sufficient to completely surround the implant. In those cases, the clinician usually employs a procedure to encourage bone formation. These procedures typically include a bone graft and/or membrane therapy. Recent advances have led to the isolation, cloning, and production of recombinant human proteins that stimulate bone formation. One of these bone morphogenetic proteins (rhBMP-2) has been extensively studied in animal models and is currently being tested in human clinical trials. METHODS: In this study, rhBMP-2 was tested using a collagen sponge carrier to stimulate bone formation in defects in the canine mandible around endosseous dental implants. Six animals had a total of 48 implants placed. rhBMP-2 with the collagen carrier was implanted around 24 of these, the remainder having only the collagen carrier placed. Half the sites were covered with a nonresorbable expanded polytetrafluoroethylene membrane. Histologic analysis was performed after 4 and 12 weeks. The area of new bone formed, percentage of bone-to-implant contact in the defect area, and percentage fill of the defect was calculated. RESULTS: The addition of rhBMP-2 resulted in significantly greater amounts of new bone area and percentage of bone-to-implant contact and with more percentage fill after 4 and 12 weeks of healing. The area of new bone formed was reduced after 4 weeks when a membrane was present but after 12 weeks, there was no significant difference between membrane and non-membrane treated sites. In some specimens, new bone was found coronal to the membranes, with rhBMP-2-treated sites having greater amounts than non-rhBMP-2-treated sites. CONCLUSIONS: These data demonstrate that a bone differentiation factor significantly stimulates bone formation in peri-implant bone defects in the canine mandible. In addition, bone-to-implant contact was significantly enhanced along the rough implant surface. Membrane-treated sites had less new bone formation after 4 weeks of healing but were similar to non-membrane sites after 12 weeks. These results demonstrate that rhBMP-2 can be used to stimulate bone growth both around and onto the surface of endosseous dental implants placed in sites with extended peri-implant osseous defects.     

Alveolar bone graft resorption associated with abnormal dental follicle

An unusual case of an alveolar bone graft that underwent almost complete resorption in association with a large radiolucent lesion around the erupting canine is reported. Clinical and radiographic follow-up after grafting is important to detect and manage any pathologic changes which might occur. Early detection of any abnormal radiologic changes and surgical intervention to excise the lesion could prevent further destruction of the grafted bone.     

Radiographic identification of nonthreaded endosseous dental implants

STATEMENT OF PROBLEM: The identification of dental implant bodies in patients without available records is a considerable problem due to increased patient mobility and to the large number of implant systems with different designs. PURPOSE: The purpose of this study was to document features that would help dentists identify non-threaded implant bodies from their radiographic images. MATERIAL AND METHODS: More than 50 implant manufacturers were contacted and asked to provide implants with dimensions as close as possible to 3.75 mm (diameter) x 10 mm (length). Forty-four implants were donated, 16 of which were identified as non-threaded. Radiographs were made of these implants at 0 degrees, 30 degrees, 60 degrees, and 90 degrees horizontal rotation combined with -20 degrees, -10 degrees, 0 degrees, +10 degrees, and +20 degrees vertical inclination relative to the radiographic beam and film. A total of 20 images per implant were taken and examined to identify consistent, unique features that would aid in implant identification. At a 20 degrees vertical inclination, vital features of implants were distorted enough to be deemed unrecognizable. Therefore, only those observations made from radiographs between -10 degrees and +10 degrees vertical inclination were used for implant identification purposes. RESULTS: All implants could be recognized from radiographs made between -10 degrees and +10 degrees vertical inclination. A series of tables and flowcharts describe the implants according to their identifying features. CONCLUSION: Information from this study should help dentists identify non-threaded endosseous implants from their radiographic images.     

Radiographic identification of threaded endosseous dental implants

STATEMENT OF PROBLEM: The identification of dental implant bodies in patients without available records is a considerable problem due to increased patient mobility and to the large number of implant systems with different designs. PURPOSE: The purpose of this study was to document features that would help dentists identify threaded implant bodies from their radiographic images. MATERIAL AND METHODS: More than 50 implant manufacturers were contacted and asked to provide implants with dimensions as close as possible to 3.75 mm (diameter) x 10 mm (length). Forty-four implants were donated, 28 of which were identified as threaded. Radiographs were made of these implants at 0 degrees, 30 degrees, 60 degrees, and 90 degrees horizontal rotation combined with -20 degrees, -10 degrees, 0 degrees, +10 degrees, and +20 degrees vertical inclination relative to the radiographic beam and film. A total of 20 images per implant were taken and examined to identify consistent, unique features that would aid in implant identification. At a 20 degrees vertical inclination, vital features of implants were distorted enough to be deemed unrecognizable. Therefore, only those observations made from radiographs between -10 degrees and +10 degrees vertical inclination were used for implant identification purposes. RESULTS: All implants could be recognized from radiographs made between -10 degrees and +10 degrees vertical inclination. A series of tables and flowcharts describe the implants according to their identifying features. CONCLUSION: Information from this study should help dentists identify threaded endosseous implants from their radiographic images.     

Macro design morphology of endosseous dental implants

STATEMENT OF PROBLEM: The identification of dental implant bodies in patients without available records is a considerable problem due to increased patient mobility and to the large number of implant systems with different designs. PURPOSE: The purpose of this study was to document the designs of selected implants to help clinicians identify these implants from their radiographic images. MATERIAL AND METHODS: More than 50 implant manufacturers were contacted and asked to provide implants with dimensions as close as possible to 3.75 mm (diameter) x 10 mm (length). Forty-four implants were donated, separated into threaded and non-threaded categories, and further sorted into tapered and non-tapered categories. The implants were examined visually, and features on the entire circumference and length of each implant were recorded and categorized as coronal, midbody, or apical. RESULTS: A series of tables describe the 44 implants according to coronal, midbody, and apical features. CONCLUSION: The results of this project offer dentists basic knowledge of the design of selected dental implants. Such knowledge can aid the radiographic identification of these implants.     

Demonstration of the osseoinductive effect of bone morphogenetic protein within endosseous dental implants

The purpose of this case report was to demonstrate the host osseous response in the maxilla after placing bone morphogenetic protein (BMP) within a specially designed implant. Under normal circumstances, it is usually necessary to wait from 4 to 6 months, or even longer in some cases, for osseous integration. Our objective was to assess the ability of BMP, which was carried on an absorbable collagen sponge in horizontal portals of the subject im plant,to affect the formation of bone in a Macaca fascicularis monkey. A control implant was loaded internally with autogenous bone recovered from the preparation of the osteotomy. The results demonstrated that osseous peri-implant healing occurs using BMP in this format.     

Mandibular distraction osteogenesis for endosseous dental implants

Patients with complete or partial edentulism who have insufficient bone for endosseous dental implant treatment present a challenge for the dental practitioner. Alveolar distraction osteogenesis is a technique for creating bone and soft tissue, without the need for bone grafting and its potential complications. In this article, alveolar distraction osteogenesis is compared with traditional bone grafting techniques. A case is presented to illustrate successful bilateral mandibular vertical distraction osteogenesis with creation of adequate bone volume for endosseous implant-supported dental restoration.     

Electron microscopy of bone response to titanium cylindrical screw-type endosseous dental implants.

This study investigated the undecalcified bone and enveloping tissues supporting commercially pure titanium one-stage and two-stage endosseous dental implants placed into the mandibles of adult mongrel dogs. Correlative light microscopy, transmission electron microscopy, and high-voltage transmission electron microscopy demonstrated a dynamic bone interface to the implants. Mineralized tissue was routinely observed within 20 to 50 nm from the implant interface, separated from the implant interface only by an electron-dense deposit. The densely mineralized collagen fiber matrix was oriented parallel to the implant interface, as were osteocytes that were found close to the interface. Osteocytic projections progressed through canaliculi, often directly to the implant interface. Unmineralized areas that appeared to have the potential for mineralization were also identified.     

Tactile sensibility of sapphire endosseous dental implants.

Experiments are described in which the tactile thresholds of sapphire (bioceram) endosseous implants were measured and compared with those of natural teeth. The effects of local anaesthesia were determined in an attempt to localize the mechanoreceptors involved. The thresholds of the implants were higher than those of natural teeth but lower than those of another type of implant (alumina tubingen) examined in another study. The results of local anaesthesia testing indicated that the sensory receptors involved were located in the connective tissues around the implant.     

Using endosseous dental implants for patients with ectodermal dysplasia.

Congenitally missing teeth and poorly developed or absent alveolar ridges are signs often associated with various types of ectodermal dysplasia. Endosseous dental implants may be used to support fixed mandibular prostheses in patients with ectodermal dysplasia. Anatomical factors and age considerations require careful attention to treatment planning.     

Lateral bone condensing and expansion for placement of endosseous dental implants: a new technique

Placement of endosseous dental implants can be a problem due to bone resorption if the patient has been missing teeth for a considerable period of time. In the literature, bone-grafting techniques have shown variable results. Additionally, bone grafting requires a longer treatment time and a need for a second surgery, and it adds significant cost to the treatment. These factors often discourage patients from having dental-implant treatment. Another technique for placement of dental implants in narrow bone ridges is repositioning and remodeling of alveolar bone by condensing and expansion with the help of bone osteotomes. This article presents 2 cases, 1 in the maxilla and 1 in the mandible, for placement of endosseous dental implants with the use of a new bone-expansion osteotome kit that utilizes a screw-type configuration for bone condensing and expansion.     

Factors associated with soft- and hard-tissue compromise of endosseous implants

This prospective analysis identifies factors associated with endosseous implant removal as well as factors associated with implant morbidity resulting in nonscheduled patient visits. Treatment of the latter conditions is discussed. The most important factors identified for implant success were surgery without compromise in technique, placing implants into sound bone, avoiding thin bone or implant dehiscence at the time of implant placement, avoiding premature implant exposure during the healing period, establishing a balanced restoration, and insuring appropriate follow-up hygiene care. In the posterior mandible, the presence of keratinized gingiva was strongly correlated with optimal soft- and hard-tissue health.