The International Journal of Oral & Maxillofacial Implants, 01/2001

The aim of the present clinical study was to determine, through histologic and histomorphometric investigations of human bone specimens, whether the addition of autogenous bone to the bone substitute material Bio-Oss can produce a high-quality implant site. To improve vertical bone height, 13 sinus floor elevations were carried out in a total of 12 patients. Augmentation of the maxillary sinus floor was completed using a mixture of Bio-Oss and bone harvested intraorally from the mandibular symphysis, the retromolar space, or the tuberosity region. Following an average of 7.1 months of healing, 36 Brånemark System implants were placed. During this surgical intervention, 23 cylinder-shaped bone biopsies were taken from the augmented maxillary region using trephine burs. Histologic analysis of the bone biopsies revealed that the Bio-Oss granulate was well-integrated into the newly formed bone; 33.1% (± 12.4%) of the substitute material surface was in direct contact with bone. Histomorphometric analysis of the samples revealed an average percentage proportion of bone of 18.9% (± 6.4%). The bovine substitute material and soft tissue occupied, respectively, 29.6% (± 8.9%) and 51.5% (± 9.4%) of the measured surface. When the implants were uncovered after an average healing phase of 6 months, all 36 implants had become osseointegrated. The combination of osteoconductive Bio-Oss and osteoinductive autogenous bone thus proved to be a material suitable for application in sinus floor augmentation.

This in vitro project investigated load transfer through screw-retained telescopic prostheses. Three Brånemark System implants incorporating strain gauges were embedded in an aluminum block. Telescopic prostheses that included 1 mesial and 1 distal cantilever were fabricated over 1 central EsthetiCone and 2 Ti-Adapt abutments. The buffering capacity of the cement in a combined screw-retained/cemented prosthesis was studied. The degree of misfit of the prostheses could be adjusted by applying shims of various thicknesses under the EsthetiCone. Load distribution was measured while a 50-N load was applied in turn over each implant and each cantilever. The results showed that tightening the central prosthetic screw widened the load distribution. The cement accommodated misfits between the layers of the telescope, significantly reducing bending moments on some supporting implants. The system exhibited a degree of tolerance to misfit and can provide a versatile prosthodontic option.

This study examined the opportunities offered by intraoral distraction osteogenesis to vertically elongate insufficient alveolar ridges and thereby improve local anatomy for ideal implant placement. Eight patients presenting with vertically deficient edentulous ridges were treated by means of the distraction osteogenesis principle with an intraoral alveolar distractor. Two to 3 months after consolidation of the distracted segments, 26 implants were placed in the distracted areas. Four to 6 months later, abutments were connected and prosthetic loading of the implants was started. The mean follow-up after initial prosthetic loading was 14 months. In all patients, the desired bone gain was reached at the end of distraction (mean vertical bone gain of 8.5 mm). Probing depth, Bleeding Index, and Plaque Index around implants were evaluated, and Periotest values were also calculated. The cumulative success rate of implants was 100%. Radiographic examinations 12 months after functional loading of implants showed a significant increase in the density of the newly generated bone in the distracted areas. This technique seems to be reliable, and the regenerated bone has withstood the functional demands of implant loading. Success rates of implants, periodontal indices of peri-implant soft tissues, and Periotest values were consistent with those reported in the literature regarding implants placed in native bone.

This multicenter prospective clinical evaluation was undertaken to determine the therapeutic success and marginal bone level stability of 3is self-tapping and ICE implants after 3 years of prosthetic loading. Between July 1995 and June 1996, 189 completely or partially edentulous patients were treated with 614 machined-surface screw-type commercially pure titanium implants (self-tapping or ICE). Two hundred seventy-seven self-tapping implants were placed in 85 patients (average age of 56 years), and 337 ICE implants were placed in 104 patients (average age of 61 years). A total of 360 implants (58.6%) were placed in posterior segments. Easier placement was reported with the ICE implant in normal or dense bone. For the self-tapping implants, survival rates of 92.9% and 91.6% were noted after 1 and 3 years of prosthetic loading, respectively. Survival rates of 95.4% and 93.8% were obtained with the ICE implant for the same periods. Late failures (after loading) were more common than early failures (before loading) for both types of implants. The marginal bone level of 238 self-tapping implants (85.9%) and of 307 ICE implants (91%) was radiographically evaluated at 3 years. Marginal bone level was at the first thread for 95.1% of implants. A loss of marginal bone level of 2 to 4 threads was noted for 4.9% of the evaluated implants. No implant showed bone loss greater than the fourth thread. Overall survival rates of 94.3% and 92.9% were obtained after 1 and 3 years of prosthetic loading, respectively, for 596 and 588 implants. Keywords: bone density, clinical trials, dental implants, multicenter study, self-tapping dental implants

The anterior maxilla represents a therapeutic challenge for single-tooth replacement with implants. The surgical trauma delivered to soft and hard tissues during implant placement can influence the future esthetic result. The clinician should use surgical techniques that prevent esthetic complications, such as increased crown length or loss of interdental papillae, without compromising osseointegration. This prospective study investigated the interproximal crestal bone loss occurring after placement of single-tooth implants using 2 different flap designs: a widely mobilized flap design that included papillae, and a limited flap design that protected papillae. The interproximal crestal bone loss was of practical importance and statistically significantly less following the use of a limited flap design versus the widely mobilized flap procedure. Keywords: alveolar bone loss, comparative study, dental papillae, implant-supported dental prosthesis, preprosthetic oral surgical procedures, single-tooth dental implants, surgical flaps

In this study, computed tomograms (CTs) of 70 patients were examined for visible vascular canals in the mandible as well as for their localization, incidence, diameter, and content. All patients examined showed at least 1 lingual perforating bone canal in the mandible. Since such vascular canals are encountered regularly, routine CT examination is recommended prior to implant surgery to help avoid severe bleeding complications during the placement of implants in the interforaminal region. Keywords: dental computed tomography, dental implants, intraoperative complications, mandibular bone canals

Forty-three patients with severely resorbed maxillae who had been referred for implant treatment were assigned to 1 of 3 treatment options: bone grafting and implant placement (graft group), modified implant placement with no bone grafting (trial group), or optimized complete dentures (no-implant group). Sixteen, 20, and 7 patients, respectively, were assigned to the 3 groups. The patients have been examined annually, and at the time of this report they had been followed for 3 to 5 years after treatment. At the 1-year follow-up, 10% (22 of 221) of the implants had been lost, and at the 2-year follow-up, 18% of the implants had been lost (40 of 221; 25% in the graft and 13% in the trial group); after that time, no further losses occurred. Life table analysis showed cumulative success rates of 82% in the graft group and 96% in the trial group after 1 year, and 74% and 87%, respectively, at the final examination after 3 to 5 years. The failure rate was higher in smokers than in non-smokers. A substantial reduction of the grafted bone, especially of onlay grafts, occurred early after grafting surgery in many patients. Mean marginal peri-implant bone loss was 0.6 mm during the period from prosthesis connection to the 1-year follow-up, and from the 1-year to the 3-year follow-up, average peri-implant bone loss was 0.3 mm in the graft group and 0.5 mm in the trial group. The results corroborated previous findings that patients with severely resorbed maxillae have an increased risk of implant failure in comparison to patients with good bone quantity and quality. However, in this investigation, practically all implant losses occurred during the first 2 years, whereupon a steady state seemed to follow for up to 5 years after loading. Keywords: bone graft, bone resorption, dental implants, oral radiography, osseointegration, sinus inlay

Indications for the most frequently used imaging modalities in implant dentistry are proposed based on clinical need and biologic risk for the patient. To calculate the biologic risk, the authors carried out dose measurements. They demonstrated that the risk from a periapical radiograph is 20% of that from a panoramic radiograph. A panoramic radiograph and a series of 4 conventional tomographs of a single-tooth gap in the molar region carry 5% and 13% of the risk from computed tomography of the maxilla, respectively. Panoramic radiography is considered the standard radiographic examination for treatment planning of implant patients, because it imparts a low dose while giving the best radiographic survey. Periapical radiographs are used to elucidate details or to complete the findings obtained from the panoramic radiograph. Other radiographic methods, such as conventional film tomography or computed tomography, are applied only in special circumstances, film tomography being preferred for smaller regions of interest and computed tomography being justified for the complete maxilla or mandible when methods for dose reduction are followed. During follow-up, intraoral radiography is considered the standard radiographic examination, particularly for implants in the anterior region of the maxilla or for scientific studies. In patients requiring more than 5 periapical images, panoramic radiography is preferred.

This study reviews the outcome of implant placement in 61 patients after augmentation of severely atrophic alveolar bone with a bovine bone mineral, Bio-Oss. Bone augmentation was performed at 4 different sites: alveolar crest width, alveolar crest height, antral cavity, or nasal cavity. After a mean healing time of 11.9 months, 231 implants were placed in Bio-Oss bone. The time of loading of the implants varied between 12 and 113 months. Calculated from the time of implant placement and irrespective of loading time, a survival rate of 80.5% for the individual implants was estimated. In most patients (73%), Bio-Oss was mixed with autogenous bone from the chin. However, the results indicated that autogenous bone may be excluded from the Bio-Oss graft. Keywords: alveolar bone loss, alveolar ridge augmentation, bovine bone, dental implants

Little information exists to define the minimum number of implants required for sufficient anchorage of mandibular overdentures. To date, 2 implants placed in the interforaminal region have been considered the minimum. The aim of this study was to examine whether a single symphyseal implant would suffice for adequate anchorage of a mandibular complete denture in elderly patients (octogenarians), and whether this surgically, prosthetically, and financially simple concept would also satisfy patients needing replacement of the mandibular dentition. Nine patients with a mean age of 82.2 years underwent placement of a single symphyseal endosseous implant and anchorage of a complete denture using a ball attachment. Standardized recall examinations, including patient response and inspections of the peri-implant soft tissue and bone conditions, were carried out at 3- to 6-month intervals for a period of 11/2 years. It was found that anchorage with a single implant led to both a significant improvement in patients subjective satisfaction (P .01) and a significant reduction in reported symptoms (P .01). During the observation phase, pocket depth and bone resorption initially increased around implants but stabilized after the sixth month. Denture management (placement and removal) also improved during the recall period (P .01). The results of this study indicate that oral rehabilitation by mandibular complete dentures anchored on a single implant can be considered an economical therapeutic alternative to a conventional mandibular complete denture for very old (octogenarian) patients. Keywords: geriatric dentistry, implant-supported dental prosthesis, mandibular complete denture, mandibular symphysis, single-tooth dental implant

This paper investigated the osteogenic potential of 6 osteoconductive grafting materials derived from human, bovine, and synthetic sources: HTR, BOP, Biogran, Laddec, Dembone, and Osteograf. Twenty-eight New Zealand rabbits were used in this study. The active group consisted of 24 animals and the control group consisted of 4 animals. The median condyle of each tibia was drilled with a 5-mm-diameter bur to form 8-mm-deep cavities. A control group included 8 osseous cavities, with 1 hole in each tibia. These cavities were washed and left unfilled. In the active group, each grafting material filled 8 osseous cavities in 8 tibiae of different animals. Half of the active and control osseous cavities were investigated with decalcified hematoxylin and eosin-stained sections. The other half were studied with scanning electron microscopy. It was concluded that Laddec bovine bone granules possessed the best potential for an osteoconductive grafting material, followed by the bioglass crystals of Biogran and the hydroxyapatite particles of Osteograf, respectively. The least potential for rapid bone formation was demonstrated by the copolymers of HTR and BOP, and Dembone allograft bone particles did not reveal active bone healing. Keywords: biocompatible osteoconductive polymers, bioglass, bone substitutes, histology, hydroxyapatite

Oromandibular dystonia with blepharospasm (also known as Brueghels syndrome, Meiges syndrome, or idiopathic orofacial dystonia) is characterized by intense and involuntary spasms of the orofacial muscles, with a frequent loss of teeth and occlusal alterations that worsen the dystonic manifestations and cause mucosal lesions that can lead to complete edentulism. The history of a patient with oromandibular dystonia who was rehabilitated with mandibular overdentures supported by endosteal implants is presented. Oral rehabilitation with implant-supported overdentures improved the situation, despite serious problems with instability. Mandibular overdentures supported by endosteal implants were satisfactorily used to re-establish occlusion, ensuring prosthetic stability and improving the dynamics of the masticatory muscles. Keywords: blepharospasm, Brueghels syndrome, oromandibular dystonia