Pages 143, Language: EnglishLaney, William R.Pages 149-155, Language: EnglishGoheen, Kevin L. / Vermilyea, Stanley G. / Vossoughi, Jafar / Agar, John R.This study evaluated the ability of practitioners experienced in the use of Brånemark implant components to impart a desired torque using handheld screwdrivers. The torque output and variability of mechanical torque devices was also examined. For clinicians using handheld screwdrivers, values ranged from 0.7 to 18.1 Ncm, 1.4 to 33.7 Ncm, and 8.2 to 36.2 Ncm for the 10-Ncm, 20-Ncm, and 32-Ncm torques respectively. The manually operated mechanical torquing devices produced torque values within the tolerances specified by their respective manufacturers at all levels. Significant variation from the manufacturer's set values were noted as a function of tightening speed with the electronic torquing device. The data indicate that there is wide variation in the ability of clinicians to perceive adequate torquing forces applied to implant components. Calibrated torquing devices are mandatory if proper torquing procedures are to be accomplished.
Keywords: abutment screws, gold screws, preload, screw loosening, torque meter, yield strength
Pages 156-162, Language: EnglishLavigne, Salme E. / Krust-Bray, Kimberly S. / Williams, Karen B. / Killoy, William J. / Theisen, FrankThe purpose of this study was to examine the effect of chlorhexidine irrigation on the periodontal status of patients with HA-coated dental implants as measured by clinical, microbiological, and immunological measures. Thirty non-adjacent implants were randomly assigned to receive a one-time irrigation with either 0.12% chlorhexidine or sterile saline, or no irrigation. All parameters were measured at baseline, 2, 5, and 8 weeks. Results showed no significant differences between any treatment modalities at any time interval. A statistically significant decrease in probing depth (P .05) occurred within the chlorhexidine and no treatment groups at all time intervals compared to baseline.
Keywords: chlorhexidine, Integral implants, implant maintenance, irrigation
Pages 163-168, Language: EnglishPiattelli, Adriano / Piattelli, Maurizio / Romasco, Nicola / Trisi, PaoloAn experimental study was done in rabbits to characterize the bone-hydroxyapatite (HA) interface by the use of histochemical staining for mineralized tissue and laser scanning microscopy (LSM) on undemineralized sections. Twenty HA-coated Sustain implants were placed in rabbit femurs and retrieved after 6 months. The specimens were then processed to obtain thin ground sections. In all specimens, there was intimate contact between bone and HA. In some portions, mineralized bone was in tight, direct contact with the HA, while in other portions, a basophilic unmineralized material was present between bone and HA. This material was thicker in areas with active bone formation upon the HA surface and had staining characteristics similar to the material present around the osteocyte lacunae. LSM showed a fluorescence present in many areas of the interface, in osteocyte lacunae, and inside the coating. An organic bonding between bone and HA can probably be hypothesized.
Keywords: hydroxyapatite, interface, laser scanning microscopy
Pages 169-178, Language: EnglishKallus, Thomas / Bessing, ChristerThe possible occurrence of loose gold and abutment screws retaining full-arch osseointegrated prostheses has been investigated. The prostheses had been in use for at least 5 years. The findings were related to clinical parameters such as accuracy of the superstructure, operator dependence, and clinical and radiological diagnosis of implant status after 5 years. The principles of the California Dental Association's (CDA) quality evaluation criteria were modified and applied in the study. Gold screw loosening was found to be related to framework misfit and was considered to be operator dependent to some extent. It is recommended that full-arch fixed prostheses be retightened after 5 years.
Keywords: CDA evaluation, framework misfit, implant survival, osseointegrated prostheses, retightening
Pages 179-183, Language: EnglishEkfeldt, Anders / Carlsson, Gunnar E. / Börjesson, GeneThis retrospective study of Brånemark implants presents results from 93 implants for single-tooth replacements placed in 77 patients from 1987 to 1990. Only two implants were lost: one before the abutment operation and one during the first year in function. Patients' reactions to the rehabilitations were very positive regarding esthetic aspects and function. The most obvious problem was related to loose abutment screws. Forty-three percent of the abutment screws had to be retightened during the follow-up period, and for this reason, nine cemented crowns had to be remade.
Keywords: complications, dental implants, partial edentulism
Pages 184-190, Language: EnglishPalmqvist, Sigvard / Sondell, Katarina / Swartz, BarbroAt the Postgraduate Dental Education Center, Örebro Sweden, maxillary implant-supported overdentures have mainly been used in either planned cases (where implants sufficient for a fixed prosthesis could not be placed) or emergency cases (originally planned for a fixed restoration but where implants lost during the healing period made such treatment impossible). Twenty-five cases were studied retrospectively. In the planned group, only two of 19 patients had lost an implant during the follow-up period with overdentures; in the emergency group, four subjects of six lost implant(s) during the same period. The total loss of implants during healing and overdenture function was 7% in the planned group and 72% in the emergency group. The curves for survival of overdentures without loss of supporting implants were significantly different (P = .00) for the planned group and the emergency group.
Keywords: Brånemark implants, complications, maxilla, overdenture
Pages 191-196, Language: EnglishHemmings, Kenneth W. / Schmitt, Adrianne / Zarb, George A.Overdentures and fixed prostheses were consecutively placed into 50 edentulous mandibles and were followed for 5 years. During this period of follow-up, 25 overdentures were supported by 68 implants with a success rate of 92.65%, and 25 fixed restorations were supported by 132 implants with a success rate of 90.15%. Postinsertion adjustment in the first year was more common for the overdentures. Thereafter, fixed prostheses had more complications and required more maintenance than overdentures, the average number of recalls per year being 2.27 and 1.57 respectively. The main complications were associated with the peri-implant mucosa, abutment and gold screws, acrylic-resin components, and retentive clips. Overdentures offer an attractive alternative to fixed prostheses in the treatment of the edentulous mandible.
Keywords: Brånemark implants, complications, edentulous mandible, fixed prosthesis, overdenture
Pages 197-206, Language: EnglishGitto, Christina A. / Plata, Walter G. / Schaaf, Norman G.The use of commercially pure titanium endosseous implants has become state-of-the-art treatment for patients with craniofacial defects. This study defined criteria that can be used in assessing the peri-implant abutment epithelium. The criteria were then used to examine overall tissue reaction. In this investigation, seven patients with percutaneous craniofacial implants were evaluated. Two of these patients exhibited adverse skin reactions that were associated with heavy sebaceous crusting, skin cultures positive for Staphylococcus aureus, higher Periotest values, and thicker peri-abutment tissue with greater mobility. It was determined that these factors can predispose the patient to local infection, which, if ignored, can result in failure of the implant. This study indicates that adequate patient hygiene is crucial to maintaining healthy tissues in the peri-implant abutment site.
Keywords: craniofacial prosthesis, peri-implant abutment epithelium
Pages 207-213, Language: EnglishBenzing, Ulrike / Weber, Heiner / Simonis, Anette / Engel, EvaAlmost all edentulous patients with implant-supported prostheses in mandibles describe an improvement in their chewing function and quality of life. This was reason to believe that an implant prosthetic treatment actually influences mandibular border movements, as well as the chewing patterns. The present study compares border movements and chewing patterns in 15 patients recorded with the Sirognathograph. The first measurements were made with existing complete dentures. After implantation and rehabilitation with a Dolder-bar and clip-to-bar overdenture, the movements were recorded again. The measurements revealed an improved guidance of the mandibular movements and larger borderline patterns following stabilization of the complete denture with the bar. This leads to more harmonic shapes in the movements and better chewing efficiency.
Keywords: border movement, chewing pattern, implant-supported complete denture
Pages 214-222, Language: EnglishIchikawa, Tetsuo / Miyamoto, Masashi / Horisaka, Yasuyuki / Horiuchi, MasonobuMarginal bone height and bone density were evaluated for 2 years after two-piece dense hydroxyapatite implant (Apaceram) placement using standardized radiography and digital image processing. The chronological changes in marginal bone height were divided into three groups: Group level was constant or became higher with time; Group II - bone decreased gradually after superstructure placement; and Group III - bone decreased in height rapidly after abutment placement. Bone density around the successful Apaceram implant, especially in the crestal region, increased clearly. The results suggest that bone resorption/formation around the implant is related to occlusal stress, and that adequate occlusal stress should be exerted on the implant at each phase after the implant placement.
Keywords: Apaceram implant, bone remodeling, dense hydroxyapatite, digital image processing
Pages 223-229, Language: EnglishBruggenkate, Christaan M. ten / Sutter, Franz / van den Berg, Johan P. A. / Oosterbeek, Hermanus S.Removal of implants is performed in cases of irreversible implant failure and in patients having psychological problems with implants. The explantation procedure can be complicated in some situations. In the present article, techniques of explantation and some related considerations are presented.
Keywords: explanation, ITI dental implants, oral implants
Pages 230-234, Language: EnglishCohen, Stephen R. / Orenstein, Jonathan H.When implants and natural teeth are combined, forces on the abutments need to be controlled so that neither the teeth nor the implants sustain excessive amounts of force. The technique described addresses reduction of potentially harmful cantilever effects in a fixed prosthesis that is facultatively removable. A nonrigid attachment is used in the implant crown. Telescopic copings are definitively cemented on the natural teeth. Provisionally cemented overcastings incorporate this nonrigid connection between the pontics and the implant crowns. The means of connection employs a semiprecision attachment in which the female connector is placed within the relatively immobile implant crown. The male connector is placed on the pontic seating into the implant crown. This relationship limits cantilever forces exerted on the natural-tooth abutment. The nonrigid connection of the tooth-supported retainer limits cantilever forces and directs occlusal loads axially in a direction along the long axis of the implant. This arrangement is acceptable as compared to the complete tooth-supported arrangement described by Shillingburg; in this situation, the implant will not migrate. Since 1986, this arrangement has been used clinically without attachment migrations, implant failure, or endodontic therapy, with only minor screw-loosening episodes.
Keywords: cantilever, implant mobility, nonrigid attachments, tooth mobility
Pages 235-238, Language: EnglishSharifi, M. Nader / Pang, lok-Chao / Chai, JohnThe screw-joint stability of single-tooth implant-supported restorations has been shown to be significantly improved with an abutment system (CeraOne) that uses a gold-alloy screw tightened at a prescribed amount of torque. The abutment system requires the cementation of the restoration to the abutment. This negates the possibility of accessing the abutment screw when the removal of the restoration is desired. This article described two alternative restorative techniques to maintain accessibility to the screw joint.
Keywords: dental esthetics, implant
