The International Journal of Oral & Maxillofacial Implants, 04/1995

This case report demonstrates the interface histology of hydroxyapatite-coated dental implants placed in a human vascularized iliac bone graft. Microscopic evaluation found a direct contact of lamellar bone to the implant surface even in areas of loose trabeculation. The hydroxyapatite coating was intact, with no evidence of resorption. This study appears to show that the healing response to hydroxyapatite-coated implants placed in vascularized bone grafts is similar to previously reported findings in nongrafted sites. Keywords: bone-implant interface, hydroxyapatite-coated implants, vascularized bone grafts

The damping behavior of 392 IMZ implants with a diameter of 4 mm was examined by performing Periotest measurements during regular implant follow-up. The results were correlated with radiographically assessed peri-implant bone reduction. To guarantee statistical independence, only one randomly chosen implant per patient was considered in the examination. In 167 implants, the difference between the mean mandibular and maxillary Periotest values proved to be statistically significant. Age, sex, and radiographic length of the endosseous part of the abutment had no influence on the Periotest values. Assessment of the Periotest values can thus be considered an additional parameter for objective determination of IMZ implant success. However, exclusive use of the Periotest method without additional radiographic examinations does not seem to be justified. Keywords: endosseous implant length, IMZ implant, Periotest

This report compares the conventional and delay methods of implantation, evaluating the bone formation around a dense apatite implant. In the conventional method, the implant is placed immediately after the cavity is prepared. In the delay technique, the implant is placed 2 weeks after preparation. This study found that many new thin trabeculae and capillaries formed around the cavity during the delay period, while none had formed at the time of implantation using the conventional method. The delay method showed earlier and wider bone formation, and less surrounding fibrous encapsulation. These results indicate that the delay technique can be an efficient method for establishing good bone binding. Keywords: apatite implant, delay method, dental implants

Twenty Brånemark implants were placed with membranes (Gore-Tex Augmentation Material) as immediate or delayed implants in the extraction sockets of 15 patients. Membrane perforations through the mucous membrane occurred in 10 patients after 6 to 24 weeks and once after 2 weeks. Histologic examination of 15 tissue samples taken when the membrane was removed showed genuine bone regeneration in three patients, connective tissue regeneration with intermittent bone regeneration in eight patients, purely fibrous healing in two patients, and inflammatory granulation tissue in two patients. The high proportion of membrane perforations with immediate implants should be taken into account in the assessment and clinical application of this therapy principle. Keywords: extraction sockets, guided bone augmentation, implants, wound healing

Selecting the abutment at second-stage implant surgery should combine the experience of both the surgeon and the restorative dentist to avoid complications during prosthetic reconstructions. If an inappropriate abutment is selected, the resultant removal of the abutment and replacement of it with a completely different one is both costly and inefficient. The availability of the healing abutment component has eliminated many of these problems. Making an impression at the implant level allows the dentist ample time to study the restorative needs before selecting the final abutment. Keywords: abutment selection, abutment try-in kit, implant level impression

The purpose of this study was to clarify the relationship between crevicular fluid volume in the osseointegrated implant sulcus and peri-implant condition. Crevicular fluid volume was measured in 63 osseointegrated implant sulci, and Gingival Index, Plaque Index, and probing depth were evaluated around the implants. The crevicular fluid volume in the sulci of osseointegrated implants with high Gingival Indexes was greater than that in those with low Gingival Indexes. The crevicular fluid volume in the sulci of the implants with high Plaque Indexes was greater than that in those with low Plaque Indexes. Keywords: crevicular fluid, Gingival Index, osseointegrated implant, Plaque Index, probing depth

Investigation of the psychological impact of implant-retained overdentures has demonstrated some positive benefits over traditional prosthetic treatment (ie, conventional complete dentures). The aim of the present study was to determine whether treatment response could be understood by controlling the degree of alveolar ridge resorption present. In a cross-sectional single-wave study by means of a questionnaire, patients who had received implant-retained mandibular dentures were compared with patients who had conventional mandibular dentures. For purposes of comparison, all patients in both groups wore conventional maxillary dentures. From the 87 patients who were invited to complete a postal questionnaire, 76 replies were received (85% response rate). The implant (n = 41) and denture (n = 35) patients were assessed on self-rated symptoms, denture satisfaction, psychological distress, body satisfaction, and self-esteem using standardized scales. All patients had the extent of alveolar bone loss classified according to Cawood and Howell's (1991) system during a clinical examination. The results indicated that the response of patients to implants or dentures was influenced by the degree of bone loss. Patients with extensive resorption who received implants appeared, from a psychological perspective, to receive more benefit than their nonimplant counterparts. Hence, there is some evidence to support the inclusion of clinical measures of alveolar bone loss when considering the psychological impact accruing from implant-based treatments. Keywords: anatomy, classification, implants, psychological distress, satisfaction, self-esteem

A prospective study of 20 patients receiving rehabilitation for a missing external ear revealed the failure of three flanged implants in a total of 60 placed for the support of a prosthesis and 10 for retention of a bone-anchored hearing aid. Factors limiting an optimal outcome were health of the cutaneous cuff around the abutments, bonding of the silicone ear to the acrylic-resin substructure, and the ability to minimize disfigurement of a congenitally deformed face. Keywords: auricular prosthesis, maxillofacial rehabilitation, skull implants

There have been many expanded applications for the use of endosseous implants in the reconstruction of partially and totally edentulous patients. The posterior maxilla, which frequently has inadequate quality and quantity of bone, and the contiguous maxillary sinus often provide poor recipient sites for endosseous implants. However, innovative procedures using autogenous, allogeneic, and alloplastic graft materials have enabled clinicians to place implants in the reconstructed resorbed maxilla. These techniques often violate the anatomic integrity and interfere with the physiologic mechanisms of the maxillary sinus, creating potential complications. Eight patients with complications following maxillary sinus augmentation and reconstruction with endosseous implants are reported. Keywords: bone graft, complications, implant, infection, maxillary sinus

A variable number of septa, also referred to as Underwood's septa, divide the floor of the maxillary sinus into several recesses and may thus cause various complications during sinus-lift procedures. The incidence of Underwood's septa was evaluated by examining 41 edentulous maxillas. In 13 of these maxillas (31.7% of the cases), sinus floors with at least one septum were observed. Most of the septa were located in the region between the second premolar and the first molar. A possible cause of septal formation could be the variable phases of maxillary sinus pneumatization of the empty alveolar process following tooth extraction. Keywords: maxillary sinus, sinus-lift technique, Underwood's septa

Nondecalcified histologic sections (from a cadaver) of 12 IMTEC implants in four jaw quadrants 1 year after surgery showed significant osseointegration. Microscopically, no apparent difference was observed in new bone growth and osseointegration in those implants placed in the maxilla or mandible, or between titanium plasma-spray-coated (TPS) implants and TPS-treated implants coated with hydroxyapatite. Areas in which implants were placed through the bony floor of the maxillary sinus showed new bone growth above the normal level of the floor of the sinus around the implants and into mechanical retention holes. Small penetrations of the maxillary sinus membrane or the lingual plate of the mandible did not affect the function of the implants, nor did they cause any symptoms. A vertical component of soft tissue around the cervical part of the osseointegrated implants, noted in histologic sections to be as much as 5 mm below the crest of the alveolar bone in at least one area, was not discernible radiographically even when 5-mm-thick sections of bone containing the implants were radiographed. Keywords: cadaver, dental implants, human, osseointegration, postmortem

The purpose of this study was to evaluate and compare the treatment of ligature-induced peri-implantitis using guided bone regeneration and two bone grafts alone and in combination. Mandibular premolars and first molars were extracted from four beagle dogs and after 3 months of healing, three Brånemark implants were placed on each side of the mandibles. Following abutment connection 3 months later, experimental peri-implantitis was induced by tying plaque-retentive ligatures around all abutments. Ligatures and abutments were removed after 3 months, and bony defects measured and treated with either: (1) debridement only; (2) debridement plus resorbable hydroxyapatite; (3) debridement plus canine freeze-dried demineralized bone; ( 4) debridement plus guided bone regeneration; (5) debridement plus resorbable hydroxyapatite and guided bone regeneration; or (6) debridement plus canine freeze-dried demineralized bone and guided bone regeneration. Pretreatment and 4-month-posttreatment comparison revealed a significant but variable degree of clinically appreciable hard tissue fill with all treatment procedures. Guided bone regeneration procedures resulted in the greatest fill, followed by bone grafts alone and flap debridement. There was no significant difference between guided bone regeneration and both guided bone regeneration/graft combinations; therefore, guided bone regeneration procedures appear to be a predictable treatment for plaque-induced peri-implant defects. Keywords: bone grafts, bone regeneration, guided tissue regeneration, implantology, peri-implantitis, regeneration, wound healing

Although the permucosal site of implants can be made to coincide with tooth position, the problem of aligning multiple abutments remains. To use the maximum amount of available bone, an implant must often be placed at an angle to the long axis of the prosthetic replacement tooth, and it also can deviate mesiodistally. This paper discusses a technique using trial abutments to create parallelism while ensuring that each abutment is ideally positioned with respect to the final restoration. The procedure also encourages patient acceptance by transferring the appearance created by a preliminary diagnostic waxup through to the finished prosthesis. Keywords: diagnostic waxup, hex guide pins, implant-abutment parallelism, osseointegrated implants, surgical template

This study evaluates mechanical behavior of retention systems that have been used in craniofacial osseointegration. A loading/measuring apparatus was custom designed and constructed. Test bases that represented a typical auricular situation were constructed. These bases allowed for three points of retention. Jigs that could be reproducibly positioned carried the reciprocal portion of the retentive components. The test apparatus provided vertical and horizontal loads in five locations. The system was used to test two ball-and-socket attachments (Dalla Bona; Nobelpharma), cast and preformed bar and clips (Nobelpharma), and three magnet systems (Dynamag; Neomag; Technovent). The loading/measuring apparatus was also used to evaluate the performance of two facial prosthetic adhesives. Retention systems employed in craniofacial osseointegration offer more predictable retention than the facial prosthetic adhesives. The mechanical retention systems are best suited to situations where tensile and shear forces will operate. Magnet systems are best used where only tensile forces are anticipated or where horizontal forces on the implants are to be avoided. Keywords: craniofacial osseointegration, facial prosthetic adhesives, mechanical evaluation, retention systems