Dental Implant System Research Articles

Patterns of tissue remodeling after placement of ITI dental implants using an osteotome technique: a longitudinal radiographic case cohort study.

The aim of this prospective study was to document radiographically tissue remodeling patterns around ITI implants placed according to an osteotome technique. In 19 consecutive patients from a private practice, 25 implants of the ITI Dental Implant System were placed subjacent to the sinus floor. Implant beds were pre-prepared with pilot drills and/or using the Summers Osteotome Kit. Bio Oss particles were mixed with autologous bone and inserted into the apex area. Implants were placed self-tapping. The sinus floors were thereby pushed up with attempts not to sever the Schneiderian membrane. Healing occurred submerged or semi-submerged and was uneventful in 24/25 implants. At 1 year, all implants had been restored with crowns or short fixed partial dentures. One implant was lost in the first 3 weeks, but was replaced 6 months later in a second attempt. Intraoral radiographs were obtained presurgically and postsurgically at 3 and 12 months. The mean preoperative distance between the sinus floor and the crest was 7.0 mm (range 2.3-10.3 mm). The mean distances between the implant apex and the initial sinus floor were: 3.66 +/- 1.74 mm mesially and 4.44 +/- 1.62 mm distally. The mean height of the new bone reaching apically and mesially to the implants was 1.52 +/- 2.48 mm at surgery, but was reduced significantly to 1.24 +/- 1.30 mm at 3 months and 0.29 +/- 1.91 mm after 12 months (Hotelling's test P< or =0.01). Similar values were obtained at the disto-apical aspects. In an attempt to assess periapical bone/graft remodeling, a novel index was applied: 0=no bone/graft visible, 1=cloudy appearance of new bone/graft, 2=clearly visible new bone/graft disappearing structures of original sinus floor, 3=new bone/graft with new cortical plate and the former boundary of the sinus floor disappearing. This index increased statistically significantly from baseline to 12 months (Hotelling's test P< or =0.02). In conclusion, this study shows that in areas with reduced bone height subjacent to the sinus, an osteotome technique may provide a minimally invasive way to obtain implant abutments predictably. The grafted area apical to the implants undergoes shrinkage and remodeling. The original boundary of the sinus is eventually consolidated and replaced by a new cortical plate. In addition to the linear measurements, the novel index may assist in assessing periapical remodeling at implants placed with an osteotome technique.

Accuracy of clinical and radiological classification of the jawbone anatomy for implantation--a survey of 374 patients.

The aim of this study was to investigate the anatomical features of edentulous jaw dental segments (eJDS) in order to offer the most reliable clinical and radiological classification of such segments in planning for implant treatment. A total of 374 patients, 156 men and 218 women, participated in the investigation. The mean age of the patients was 46 years (SD 12.7), ranging between 17 and 73 years. The eJDS were estimated by means of orthopantomogram, computerized tomography, and intraorally with special ridge-mapping callipers for measurement of alveolar process width. A total of 792 screw-shaped and 1-stage Osteofix Dental Implant System (Oulu, Finland) implants were inserted. Dental segments were divided according to the results of the commonly accepted eJDS assessments into 3 clinical-anatomical types. Type I indicated insignificant or no atrophy of eJDS (232 patients with 476 implant sites; 60.1% of the total number). Type II indicated mild to moderate vertical or horizontal atrophy of eJDS (100 patients with 222 sites; 28% of the total number). Type III indicated significant vertical or horizontal atrophy of eJDS (42 patients with 94 sites; 11.9% of the total number). The accuracy of the clinical and radiological classification was adjudged to have been 95.8%. By the process of establishing clinical and radiological classification of the jawbone segments, more reliability was anticipated regarding the insertion of implants both in maxillae and mandibles.

A method for seating an implant-supported fixed prosthesis on ITI solid abutments.

The solid abutments of ITI implants (ITI Dental Implant System; Straumann AG, Waldenburg, Switzerland) are prepared for cemented restorations. Fabrication of the restoration does not differ from the conventional method for fabricating fixed restorations. Abutments may be prepared or modified according to esthetic demands, available space, and the path of insertion. Correcting the preparation of solid abutments intraorally may not be as precise as on the definitive cast, especially when several abutments need correction. In addition, after preparing the abutments, the prefabricated components (positioning cylinder, abutment analog and burnout plastic coping, ITI Dental Implant System; Straumann AG) for making the impression cannot be used, and a conventional impression of the prepared abutments must be made. This article describes a method for making a perforated coping on the definitive cast for preparing the intraoral solid abutments to facilitate the seating of a metal framework. This method may be used as an adjunctive technique for fabricating implant-supported restorations when intraoral preparation is not feasible or some problem has been detected. PROCEDURE

Implant-retained mandibular overdentures with immediate loading: a 3- to 8-year prospective study on 328 implants.

The purpose of this study is to evaluate prospectively survival and success rates of implants placed in the interforaminal area of edentulous mandibles and immediately loaded with an implant-supported overdenture. Eighty-two patients, 33 males and 49 females, aged between 42 and 87 years (mean age 58.6 yr), presenting edentulous mandibles were rehabilitated with an implant-supported overdenture in the mandible. Three hundred twenty-eight screw-type osseointegrated implants (164 Ha-Ti, Mathys Dental, Bettlach, Switzerland; 84 ITI Dental Implant System, Straumann Institute, Waldenburg, Switzerland; 40 Brånemark Conical, Nobel Biocare AB, Gothenburg, Sweden; 40 Frialoc, Friatec, AG Mannheiti, Germany), were placed in the intraforaminal area of the mental symphysis (4 implants per patient). Immediately after implant placement, a U-shaped gold or titanium bar was fabricated and implants were rigidly connected with the bar and immediately loaded with an implant-retained overdenture. Success rate of implants was evaluated clinically and radiographically every year after the loading of the prostheses according to the following parameters: (1) absence of clinical mobility of implants tested individually after bar removal, (2) absence of periimplant radiolucency evaluated on panoramic radiographs, (3) absence of pain and radiologic or clinical signs of neural lesion, and (4) periimplant bone resorption mesial and distal to each implant less than 0.2 mm after the first year of prosthetic load. Of 328 implants placed, 296 were followed up from a minimum of 36 months to a maximum of 96 months, with a mean follow-up of 62 months. Seven implants in 6 different patients were removed owing to loss of osseointegration, whereas 18 implants, although still osseointegrated, did not fulfill success criteria due to bone resorption > 0.2 mm/year after the first year of loading. Despite implant losses, all patients maintained their bars supporting overdentures, although in 6 patients they were supported by 3 instead of 4 implants. The only patient who lost 2 implants received 2 new implants, which survived normally. Therefore, the absolute success and survival rates were 91.6% and 97.6%, respectively, whereas the cumulative survival and success rates of implants obtained with a life table analysis were 96.1% and 88.2%, respectively. Results of this study seem to demonstrate that survival and success rates of immediately loaded implants placed in the intraforaminal area of the mandible and rigidly connected with a bar through an implant-supported overdenture are consistent with those reported in the international literature as far as delayed loading is concerned after 3 years of loading. After longer observation times, this study demonstrated that, while survival rates of implants and bar-supported overdentures are still consistent with results published in the international literature pertaining to delayed loading, a moderate decrease in success rates of implants was found. Nevertheless, it must be stressed that this decrease (88.8 and 90.4% after a 7- to 8-year observation period for Ha-Ti and ITI implants) is related only to two implant systems; no data are available for the other two implant systems because of the shorter follow-up period.

Instrument for extraction socket measurement in immediate implant installation.

The aim of the present study was to create an instrument and a computer program for measurement of extraction sockets and for planning of the immediate replacement of teeth using screw-shaped dental implants. Ten titanium screw-shaped Osteofix Dental Implant System implants (Osteofix, Oulu, Finland) were immediately installed after extraction in nine patients, four women and five men (age 17-62 years). The measurements of fresh extraction sockets were taken at six points (mesio-buccal, buccal, disto-buccal, disto-lingual, lingual and mesio-lingual) using an instrument created by the author. The area of no contact between bone and dental implant was 11-40% (mean 31%, SD 9%), calculated by computer program. If less than 30% of the implant surface area would be in contact with the bone, immediate replacement was abandoned because sufficient primary stability could not be achieved. Guided bone regeneration was promoted by covering the implant and bone defect with deproteinized bovine bone mineral (Bio-Oss, Geistlich AG, Wolhusen, Switzerland) and bioresorbable collagen membrane (Bio-Gide, Geistlich AG), fixed in place with resorbable pins (Resor Pin, Geistlich AG). After 6 months a considerable, statistically significant (P < 0.05) defect reduction of 90% (SD 7%) was noted. It was concluded that an instrument and a computer program created for extraction socket measurement are useful in some borderline cases when there is lack of bone and the success of one-stage implantation is doubtful.

Healing after standardized clinical probing of the perlimplant soft tissue seal: a histomorphometric study in dogs.

Clinical probing of the soft tissues around oral implants has become a frequently used parameter for clinical monitoring. However, the healing of the disruption of the soft tissue seal as a result of probing has not yet been studied. The purpose of this study was to evaluate the healing events in the periimplant mucosal tissues following standardized clinical probing. In three foxhounds the mandibular premolars were extracted and, after 3 months of healing, TPS screw-shaped implants (ITO Dental Implant System) were installed. A plaque control regimen was performed throughout the duration of the experiment. After 3 months of healing of the transmucosal implants, clinical implant stability and healthy periimplant mucosal tissues with mostly absence of bleeding on probing were obtained. Clinical probing of the mesial and distal implant sites was performed immediately before 1, 2, 3, 5 and 7 days prior to the sacrifice of the animals. A specially manufactured titanium cylinder with a mesial and distal groove was fixed to the implants to standardize the insertion geometry of a pressure-sensitive probe (0.2-0.25 N, tip diameter 0.45 mm). The distances from the alveolar crest to the coronal border of the connective tissue adaptation to the implant and the length of the epithelial attachment were measured histomorphometrically in nondecalcified ground sections. The buccal and lingual aspects of the implants were used to determine the components of the biological width in unprobed control sites. The probe caused a separation between the surface of the implant and the junctional epithelium, but not within the connective tissue adaptation. In general, the probe tip was located at the most coronal level of the supracrestal connective tissue as determined histologically. By 1 day after separation of the periimplant mucosal tissue by probing, an epithelial attachment of approximately 0.5 mm in the apico-coronal direction was observed. The length of the epithelial adaptation showed a tendency to increase over time (day 2: 1.15 mm, day 3: 1.52 mm), and was complete at day 5 (1.92 mm). At the unprobed sites the epithelial attachment showed a mean length of 1.69 mm. Inflammatory infiltrates were practically nonexistent, indicating the absence of tissue trauma or infection as a result of probing. Clinical probing around osseointegrated implants does not appear to have detrimental effects on the soft tissue seal and, hence, does not seem to jeopardize the longevity of oral implants. The 'healing of the epithelial attachment' seems to be complete 5 days after clinical probing.

Bone reactions adjacent to titanium implants subjected to static load of different duration. A study in the dog (III).

The aim of the present experiment was to study the effect of a long-standing lateral static load on the peri-implant bone. Three beagle dogs were used. The mandibular premolars were extracted and 12 weeks later 3 titanium implants (ITI(R) Dental Implant System) were installed in each quadrant. Crowns were fitted to all implants 12 weeks after the installation procedure. The anterior and central crowns were fused and connected to the posterior crown by an expansion screw. In the right side of the mandible, the expansion screws were activated every 2 weeks during a 46-week period. During the last 10 weeks of this period, an expansion force similar to that of the right side was applied in the left. The animals were sacrificed and block biopsies of each implant site harvested and prepared for histological analysis. Sites subjected to 10 weeks or 46 weeks of lateral load had a similar (i) distribution of bone markers (ii) proportion of bone density and (iii) degree of bone-to-implant contact. The proportion of fluorochromes was higher at sites subjected to 10 weeks of loading than at sites subjected to 46 weeks of loading.

Single stage surgery combining transmucosal implant placement with guided bone regeneration and bioresorbable materials.

The aim of the present clinical study was to test whether peri-implant bone defects can successfully be filled with bone by applying bioresorbable materials for guided bone regeneration (GBR) procedures in conjunction with implants in the transmucosal healing position. Three women and 7 men ranging in age from 32 to 68 years (median 54.5) needed tooth replacement with dental implants. Eight to 14 weeks following careful tooth extraction, implants of the ITI Dental Implant System were placed at the extraction sites. At this time, all implants presented dehiscence defects of the alveolar bone partly exposing the rough titanium plasma sprayed (TPS) surfaces. GBR procedures were performed using deproteinized bovine bone mineral (Bio-Oss) as a membrane-supporting material and a bioresorbable collagen membrane (Bio-Gide) as a barrier. The membranes and the flaps were adjusted to fit around the necks of the implants, thus leaving the implants extending transmucosally into the oral cavity. Clinical measurements were taken at 6 sites around each implant (mesio-buccal, buccal, disto-buccal, disto-lingual, lingual, mesio-lingual) using a calibrated periodontal probe. These included: i) defect depth measured from the shoulder of the implant to the first bone-to-implant contact, ii) infrabony defect component measured from the bone crest to the first bone-to-implant contact, iii) defect width measured from the crest to the implant body in a direction perpendicular to the long axis of the implant. The Wilcoxon Matched Pairs Signed Rank Test was applied to detect differences over time. At baseline, the mean defect depth per patient amounted to 3.6 mm (Standard Deviation 1.6 mm, range 1.8-6.8 mm). The deepest extensions of the defects were located at the buccal aspects (mean 7.8 mm, SD 1.9 mm). At re-entry, the mean defect had decreased to 2.5 mm (SD 0.6 mm). This difference was statistically significant (P < 0.01). Initially, in 62% of sites the depth ranged from 0-3 mm, in 23% it ranged from 2-4 mm, and in 15% it amounted to more than 6 mm. Six to 7 months later, at re-entry, 95% of sites were 3 mm and less in depth and 5% ranged from 4-6 mm. Defect resolution, as assessed by the amount of coverage of the initially exposed rough implant surface, reached a mean value of 86% (SD 33%). One hundred percent resolution was accomplished at 8 out of 10 implants, 60% at one and 0% at another implant. The tissue at the latter implant showed signs of infection and inflammation during the healing phase. It is concluded that bioresorbable materials in GBR procedures at transmucosal implants can lead to successful bone regeneration into peri-implant defects.

Nonsubmerged implants in the treatment of the edentulous lower jaw: a 5-year prospective longitudinal study of ITI hollow screws.

Although most implant systems have been designed for a two-stage surgical technique, a one-stage surgical technique has always been advocated for the ITI Dental Implant System (Straumann AG, Waldenburg, Switzerland). A new generation of ITI implants was presented in 1988 and included a hollow cylinder, a hollow screw, and a solid screw. The goal of this study was to evaluate the one-stage surgical technique in connection with the ITI hollow screw in a longitudinal study over 5 years. Forty-six patients with edentulous lower jaws were supplied with ITI hollow-screw implants. Patients who requested an overdenture (n = 18) had four implants inserted; those who requested a fixed bridge (n = 28) had five to six implants. The patients have been followed annually for 5 years. There was a dropout of three patients (6.5%); one patient did not want to cooperate, one moved from the area, and one was deceased. The clinical examinations included bridge removal for evaluation of the individual implant stability in connection with the 1-, 3-, and 5-year examinations. Radiographic examinations were performed with intraoral radiographs and the long-cone technique. The survival rate after 5 years was 95.7%. The success rate (in which implants undergoing treatment of peri-implantitis were not counted as successes) was 91.4%. The mean marginal bone loss between the baseline and the 1-year examination was 0.1 mm and between the 1- and 5-year examinations was 0.1 mm. These changes in marginal bone level were not significant. The success rate of ITI hollow-screw implants in the edentulous mandible was 91.4% after a 5-year observation period. There was no significant change in mean bone level between the loading of the implants and the 5-year examination. Peri-implantitis was diagnosed in three patients with poor oral hygiene, and it affected six implants. Five of these failed in spite of treatment.

The development of the ITI DENTAL IMPLANT SYSTEM. Part 1: A review of the literature.

In a short trip through more than twenty years, the development of the ITI DENTAL IMPLANT SYSTEM is described. The systematic unfolding and continuous advancement of the system, permanently supported and accompanied by scientific work in clinical and general practice, is outlined in short paragraphs. Some major milestones are emphasized and characterized.

Fractured prosthetic abutments in osseointegrated implants: a technical complication to cope with

In the present report a repair set to retrieve fractured abutments remaining in the implants of the ITI Dental Implant System is presented. In 1 case in which such fractures occurred, the repair set was successfully applied. After removal of all particles of the fractured prosthetic abutments and recutting the threads, new abutments were used, and the original suprastructure could be reinserted. The causes for such technical failures are discussed considering the relatively sparse information in the literature on that topic.

Clinical Experience with One-Stage, Non-Submerged Dental Implants

This review article describes the scientific documentation of one-stage, non-submerged dental implants. In the past 25 years, numerous in vivo studies have demonstrated that non-submerged titanium implants achieve osseointegration as predictable as that of submerged titanium implants. This observation was confirmed in prospective clinical studies, mostly done with the ITI Dental Implant System. ITI implants have been widely documented for up to 10 years of prospective follow-up at various centers. All studies showed success rates well above 90%. In summary, the non-submerged approach is a true alternative to the original healing modality with submerged titanium implants. The non-submerged approach offers several clinical advantages: (i) the avoidance of a second surgical procedure and less chair time per patient, resulting in overall reduced treatment cost; (ii) the lack of microgap at the bone crest level, leading to less crestal bone during healing and resulting in a more favorable crown-to-implant length ratio; and (iii) a simplified prosthetic procedure, presenting an ideal basis for cemented implant restorations. Due to these significant clinical advantages, the non-submerged approach will become more important in implant dentistry in the near future, particularly in implant sites without esthetic priority.

Non-submerged implants in the treatment of the edentulous lower jar. A 2-year longitudinal study.

Non-submerged ITI Bonefit implants (ITI Dental Implant System) were inserted in edentulous lower jaws of 46 patients. The patients were provided with either a fixed prosthesis or an overdenture, and has been followed during a 2-year-period. At the 1-year examination, the suprastructures were removed permitting test of the individual implant stability. Radiographic examinations were performed in connection with the loading of the implants and at the 1-year examination. In total 216 implants were inserted. 4 implants were lost before loading and 4 during the 2nd year of function, which gives a survival rate after 1 year 98% and after 2 years of 96%. The mean marginal bone loss during the first year of function was 0.1 mm. However, the marginal bone changes had a high degree of variation and four implants showed a severe bone loss. The intention is to follow this patient group with annual examinations during 5 years.

Correlations between radiographic, clinical and mobility parameters after loading of oral implants with fixed partial dentures. A 2-year longitudinal study.

The aim of present study was to correlate the changes in the peri-implant tissues occurring after functional loading of non-submerged titanium implants and assessed by radiographic, clinical and mobility measurements. 11 patients with distal extension situations received 18 implants of the ITI Dental Implant System. After a healing period of 3 months, the suprastructures were fabricated and seated 5 months post-surgically. For the assessment of peri-implant bone changes, standardized vertical bitewing radiographs with reproducible exposure geometry were evaluated using computer assisted densitometric image analyses (CADIA) and bone height measurements. Since the radiographic evaluations were performed at mesial and distal sites only, the clinical parameters from these implant aspects were included in the analysis. Clinical periodontal parameters modified for the use around implants were obtained, damping characteristics were expressed as Periotest readings and standardized radiographs were obtained at 1, 3, 6, 12 and 24 months after loading. In addition, radiographs were also taken at the start of functional loading. The data obtained from this small sample of implants demonstrated a wide range of different tissue alterations when using radiographic, clinical and mobility assessments. The parameters of probing attachment level (PAL) in combination with radiographic parameters obtained at 1, 3, and 6 months after loading were good predictors for the peri-implant tissue status at 2 years. This was shown by means of multiple stepwise regression analyses. Mobility measurements did not reveal valuable predictive information with the statistical models applied. Assessments of probing attachment levels using periodontal probes rendered information on peri-implant tissue alterations, which were closely correlated to the radiographically measurable peri-implant bone changes.

Transversal fixation of restorations in combination with the Octa abutment of the ITI Dental Implant System.

In aesthetically demanding locations of the dentition, the replacement of a single tooth by means of an oral implant is often difficult because of technical limitations of the abutments systems used. The transversal Fixation System in combination with the Octa abutment of the ITI Dental Implant System presents a novel development to overcome these limitations. The report describes the engineering and design of this technical development.

The development of the ITI Dental Implant System as a model for the cooperation between research and industry

For thirty years now oral implants and methods for implantation have been developed further to assure a lifetime stability of these devices and to optimize function and esthetics. Coming from osteosynthesis the Institut Straumann in cooperation with leading clinicians had a considerable share in this development. Out of this longtime cooperation an institutionalized form was devised, where clinicians, material scientists and engineers were united in the International Team for oral Implantology (ITI). This scientific organization, although legally and financially independent from Institut Straumann, works in close cooperation with the company in an unique form of symbiosis. The ITI takes care of research and education of clinicians and practitioners and it gives the needed input for the development of new products to the Institut Straumann as its exclusive licensee. The company again pays license fees to the ITI Foundation enabling thus a continuous scientific clinical research. Over many years a whole philosophy and implant system - the ITI Dental Implant System - was developed this way with its sound scientific background.

Heat generated during preparation of titanium implants of the ITI Dental Implant System: an in vitro study.

The aim of the present study was to assess in vitro the heat generated within the implant body when preparing titanium implants of the ITI Dental Implant System to estimate the potential risk of tissue damage of individual abutment preparation. The speed and the pressure were applied according to routine clinical procedures used in the patient's mouth. Much attention was paid to ensure optimal cooling at the point where the implant and secondary part were being cut. For each of 3 preparations the change from the original temperature was measured over a period of 40 s. Each type of preparation was repeated on 5 implants fitted with temperature probes. Three different preparatory procedures performed with rotating diamond burs and stainless steel finishing burs under cooling with spray from the dental unit may result in a maximal increase in temperature of 10 degrees, 7 degrees and 3 degrees measured coronally, both at the implant shoulder and at the coronal extent of the plasma-sprayed surface after 10 s. The use of additional spray and pressured air significantly reduced this maximal increase to 5 degrees C, 5 degrees C and 4 degrees C, respectively at 10 s. At the 30-s and 40-s time points, all the measured temperatures were significantly lower. Preparation of implants or abutments does not lead to detrimental effects on peri-implant tissues provided that adequate cooling with spray is used. However, without cooling, extreme overheating could be provoked, reaching the critical temperature that would lead to irreversible bone damage within only a few seconds.

Bone apposition onto oral implants in the sinus area filled with different grafting materials. A histological study in beagle dogs.

The placement of oral implants into jaw bone has a high predictability provided an adequate bone volume surrounding the implant is present to ensure primary stability and resistance to functional loading forces after completion of osseointegration. In the distal area of the maxilla, an adequate bone volume is often lacking because of the proximity of the sinus cavities. The aim of this study was to evaluate histologically the simultaneous placement of endosseous implants into the sinus cavity and the surgical elevation of the sinus floor including filling the cavity with different grafting materials. In 9 sinus areas of 5 beagle dogs, 9 titanium implants (ITI Dental Implant System) were placed, and the void space of the sinus cavity was filled simultaneously with either demineralized freeze-dried human cortical bone (Musculoskeletal Transplant Foundation), resorbable hydroxyapatite (Osteogen) or natural cancelleous bovine bone mineral (Bio-Oss). To study bone formation, fluorochrome markers (tetracycline HCl and calcein green) were used at 2 and 8 weeks. Clinically, all implants healed uneventfully, and 5 months after implant placement the dogs were killed for histologic evaluation. All implants exhibited osseointegration within the pre-existing cortical bone of the sinus floor. The implants surrounded by freeze-dried bone xenografts yielded no formation of new bone, whereas the sites with hydroxyapatite or natural bovine bone mineral demonstrated newly formed bone with direct contact at the implant surface. The average extent of bone to implant contact was 25% (SD = 10.6%) and 27% (SD = 8.8%), respectively in relation to the length of the originally denuded implant surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Prosthetic possibilities using endosseal implants as anchorages--an epidemiological study in 65-year-old subjects.

In order to evaluate the possibility of using endosseal implants (ITI Dental Implant System) and implant-retained prostheses for 65-year-old patients from a medium-sized Finnish city, 431 such patients were examined by means of panoramic radiographs. The population represents 61% of the total age group in the city (born in 1923). The possibility to construct a prosthesis, anchored on implants, was evaluated in three different groups. It was shown that in group I (edentulous maxilla and mandible, 256 patients) all male and 97% of female subjects could have been treated with implant-retained over-dentures in the lower jaw. Corresponding figures in the upper jaw were 62% for males and 59% for females. In patients with edentulous maxilla and dentulous or partially edentulous mandible (group II, 84 subjects) implant-retained overdenture in the maxilla could have been possible in 52% of male and 43% of female participants. In subjects with own teeth left in both jaws (group III, 91 participants) some kind of implant-retained bridge or single implants could have been constructed in 70% in maxilla and in 92% in mandible.

A clinical and radiographic assessment of a porous-surfaced, titanium alloy dental implant system in dogs.

A new endosseous dental implant system incorporating a porous-surface geometry with a tapered, truncated-cone shape was placed bilaterally in edentulous areas of dog mandibles in a two-stage procedure. All implants had been stabilized by bone ingrowth by the time of the second procedure (insertion of a transgingival collar and implant-supported bridge). The transgingival collar had a porous-surface geometry on its apical one-third, and was meant to encourage gingival connective tissue ingrowth and attachment, but in fact provided an excellent milieu for bacterial contamination. As a consequence, many of the implants showed clinical and radiographic signs of impending failure by eight months. Only those implants for which the porous coat, including that of the transgingival collar, was completely submerged in bone were observed to be successful. This study reports on the radiographic and clinical assessment of this implant system in dogs during the period of function.