The International Journal of Oral & Maxillofacial Implants, 02/2004

Purpose: This study evaluated the quality of coatings on titanium surfaces prepared by discharging in Hanks' balanced salt solution without organic molecules (HBSS-). Materials and Methods: 10×10×1.0-mm titanium plates were used as cathodes of a coating device developed in the laboratory and immersed in HBSS-. A piece of platinum foil was used as a counterelectrode. Discharging was maintained at 1 A and 10 V (416 mA/cm2) for periods of 90, 270, and 540 seconds. Crystal phases of the coatings were identified by x-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). In addition, the surface characterization and Ca/P atomic ratio of the titanium surfaces were determined by x-ray photoelectron spectroscopy (XPS). Furthermore, the surface topography, the thickness of the coatings, and the bonds between coatings and titanium substrates were observed by scanning electron microscopy. Results: The FTIR and XRD studies demonstrated that the deposits on the titanium after 540 seconds of discharging were crystalline hydroxyapatite. In addition, the thickness of the titanium suboxide layer increased during discharging. The XPS studies indicated that after 540 seconds of processing, the mean Ca/P ratio of the coatings on the titanium was 1.71, which is similar to that of human bone. Discussion: In addition, the replacement of sodium ions with calcium ions seemed important for the promotion of crystallization of the coating. Furthermore, the XPS studies demonstrated that the coatings had a gradient function. Scanning electron microscopy showed that adhesion between coatings and the titanium substrate was close. The coatings were approximately 1 µm thick. Conclusion: These findings suggest that a very thin crystalline bonelike hydroxyapatite coating with a gradient function could be prepared on a titanium metal substrate in HBSS- by a discharging method.

Purpose: Bioactive glass bonds to bone through a calcium phosphate layer that mimics the structure of the mineral phase of bone. Formation of this layer is inhibited in the presence of serum protein. The authors hypothesize that creation of a calcium phosphate layer on the surface of bioactive glass before implantation will enhance bone regeneration and graft material resorption in bone defects. Materials and Methods: Bioactive glass particles covered with a layer of amorphous calcium phosphate (BG-ACP), bioactive glass particles covered with a layer of hydroxycarbonate apatite (BG-HCA), and unmodified bioactive glass particles (as a control) were prepared and implanted in cortical bone defects in dogs or in human maxillary cavities. Ungrafted sites were also used as a control. Results: Histomorphometric analyses showed significantly more bone tissue regeneration and graft material resorption in the defects filled with BG-HCA than in those filled with BG-ACP or unmodified bioactive glass (P .0001). Moreover, measurements of radiographic density of the grafted areas suggested a higher rate of bone regeneration in defects filled with the modified bioactive glass than in those filled with unmodified bioactive glass or in the ungrafted control. Bone formation was significantly greater in defects filled with unmodified bioactive glass particles than in ungrafted defects. Discussion: The enhancement of bone regeneration could be explained by the ability of the apatite layer to facilitate bone adsorption and enhance calcium release, which stimulates osteoblast differentiation and bone formation. Conclusion: Results of both the clinical and animal studies suggest that the use of surfacemodified bioactive glass covered with a hydroxycarbonate apatite layer has the potential to accelerate bone formation and graft material resorption better than unmodified bioactive glass.

Purpose: This study evaluated the deformation of a metallic framework connected to 15 stone casts fabricated using 3 transfer techniques to determine the most accurate impression procedure. Materials and Methods: Five stone casts were made from polyether impressions of an epoxy resin master model for each transfer technique. Group 1 samples were created by the direct splinted technique (square transfer copings splinted with carbon steel pins and autopolymerizing acrylic resin, custom tray); group 2 samples were made by the direct nonsplinted technique (square transfer copings, custom tray); and group 3 samples were fabricated using the indirect technique (tapered transfer copings, custom tray). Sixteen strain gauges were fixed on the framework to measure the degree of framework deformation for each stone cast. Pairs of strain gauges placed opposite each other constituted 1 channel to read deformation (half Wheatstone bridge). Deformation readings were collected at the 4 segments between abutments in 4 directions (anterior, posterior, superior, and inferior). Deformation data were analyzed using analysis of variance and the Tukey test at the .05 and .01 levels of significance. Results: Group 1 samples allowed the most accurate reproduction of analog position compared to the samples made using the other techniques. No significant difference was found between the direct nonsplinted (group 2) and indirect (group 3) techniques. Discussion: Although some studies have evaluated transfer techniques with similar methodology, this study demonstrated the most suitable strain gauge setup to record framework deformations in all directions and simultaneously offset the effects of temperature variation. Conclusions: The direct splinted technique was the most accurate transfer method for multiple abutments compared to direct nonsplinted and indirect techniques.

Purpose: Lack of bone height in the posterior maxilla often necessitates augmentation prior to or simultaneously with dental implant placement. The purpose of this clinical study was to evaluate the use of the natural bone mineral Bio-Oss alone or in combination with autogenous bone in sinus floor elevations performed as 1- or 2-step procedures. Materials and Methods: Thirty-eight patients required sinus augmentation. Natural bone mineral alone was used in sinus floor augmentation in 21 patients. In 13 patients, a mixture of the bone substitute and autogenous bone was used, and in 4 patients autogenous bone alone was used. In all of the patients, samples were taken for biopsy 3 to 8 months postoperatively, and bone regeneration was evaluated histologically and histomorphometrically. Results: In all patients, the amount of new bone significantly increased over the observation time, while marrow areas decreased. There was no statistically significant difference in the amount of new bone formation between the Bio-Oss group (new bone 29.52% ± 7.43%) and the Bio-Oss/autogenous bone group (new bone 32.23% ± 6.86%). In the 4 patients treated with autogenous bone alone, a greater amount of newly formed bone was found; however, in these cases the area volume filled was smaller than in the other 2 groups. Discussion: The data showed that new bone formation takes place up to 8 months after sinus floor elevation and that there is no difference in the amount of bone formation between procedures done with the bone substitute alone or with the mixture of the substitute and autogenous bone. Conclusion: These data suggest that predictable bone formation can be achieved with the use of Bio-Oss.

Purpose: In implant dentistry, the level of bone attachment is normally assessed by clinical and radiologic parameters. In the literature, however, the accuracy of these measurements has been a source of controversy. The purpose of this study was to assess the reliability of attachment measurements in the beagle dog model. Materials and Methods: In 6 beagle dogs, a total of 60 implants were placed. Bony defects resulting from plaque accumulation were treated surgically. All defects were evaluated at the time of surgery (T3) and 4 months later (T4). Evaluation included standardized measurements on radiographs, pressure-forced implant probing, and histometry. Furthermore, both conventional and digital radiographic techniques were used. Results: Both radiographic techniques showed very similar results at T3 and T4. At time T4, pressure-forced probing revealed statistically significantly different values than those obtained with radiography and histometry. When radiographic and histometric measurements were compared, no significant differences were found at either time T3 or time T4. Discussion: In this study, histometry showed better accordance with radiography than with pressure-forced probing. These results support the hypothesis that peri-implant attachment should be evaluated with a combination of both clinical and radiologic parameters. Conclusion: The exclusive use of radiography cannot be recommended for the measurement of peri-implant attachment.

Purpose: In this retrospective study, marginal peri-implant bone height around machined and sandblasted/ acid-etched interforaminal implants in the mandible was evaluated radiologically at least 3 years after functional loading. Materials and Methods: Fifty-one patients, each with 4 interforaminal screw-type implants placed between 1994 and 1998, were included in this study. Of these, 36 patients (70.6%) with a total of 144 implants (76 machined Mk II implants and 68 sandblasted/acidetched Frios implants) were available for follow-up studies. Interforaminal marginal bone loss was evaluated by extraoral rotational panoramic radiographs. In addition, predictive factors such as patient age and sex, nicotine use, implant position, implant life, and site of measurement were recorded, as well as bone loss at surgery (ie, baseline bone loss). Analysis of covariance for repeated measurements was used for statistical analysis. Between-group differences were expressed as least square means ± standard error. Results: Sandblasted/acid-etched implants showed significantly less marginal bone loss than machine-surfaced implants (2.4 ± 0.23 mm vs 1.64 ± 0.27 mm). Implants placed in the anterior of the arch showed significantly more peri-implant bone loss than implants placed in the posterior (P = .0001). Discussion and Conclusions: Significantly less long-term peri-implant bone loss was observed for rough implant surfaces compared to machine-surfaced implants. However, it was also demonstrated that both types of implants, in combination with bar-supported overdentures, can produce excellent long-term results in the atrophic edentulous mandible. Mesially placed implants showed more bone resorption than distally positioned implants, independent of surface roughness.

Purpose: The aim of the present study was to evaluate retrospectively both the results of using a mixture of bovine hydroxyapatite (BHA) and fibrin glue as the only grafting material in the floor of the maxillary sinus and the outcome of nonsubmerged implants placed later. Materials and Methods: A total of 50 consecutive patients (71 maxillary sinuses) were augmented with a mixture of BHA and fibrin glue. The grafts were allowed to heal for a mean of 8 months prior to implant placement. A total of 218 solid titanium screw-type implants were placed in a nonsubmerged fashion and allowed to heal for a mean of 10 weeks before loading (range, 10 days to 10 months). The outcome of the placed dental implants was evaluated retrospectively. Results: Twelve implants were lost, giving a cumulative survival rate of 94.5% after a mean loading time of 20 months (range, 6 to 42 months). Discussion: This study shows that augmentation of the maxillary sinus with a BHA/fibrin glue mixture and later placement of nonsubmerged implants with short healing times preceding functional loading can be a predictable concept. However, the use of autogenous bone and placement of submerged implants in the grafts with long healing times is routine in many clinics. This article discusses the evidence on which this protocol is based. Conclusion: The short-term results from this retrospective clinical study indicated that BHA/fibrin glue can be used as a grafting material without autogenous bone in the maxillary sinus to produce a high survival rate for later placement of nonsubmerged implants.

Purpose: The purpose of this study was to evaluate the accuracy of measurement of distance on the images produced by limited cone-beam computerized tomography (CT). Materials and Methods: Five cadaver mandibles were examined by spiral computerized tomography (SCT) and limited cone-beam computerized tomography (LCBCT). The vertical distance from a reference point to the alveolar ridge was measured by caliper on the sliced mandible, and measurement error on the CT images was calculated in percentages based on the actual values and the measurement values obtained from the CT images. Results: Measurement error was determined to range from 0 to 1.11 mm (0% to 6.9%) on SCT and from 0.01 to 0.65 mm (0.1% to 5.2%) on LCBCT, with measurement errors of 2.2% and 1.4%, respectively (P .0001). Discussion: This study suggests that distance can be measured accurately using LCBCT. The size of the rectangular solid images obtained using LCBCT (30 mm wide and 42.7 mm long) is thought to be adequate for observation of mandibular bony structure and for preoperative assessment before dental implant placement. Conclusion: In this experiment on cadaver mandibles, LCBCT was shown to be a useful tool for preoperative evaluation in dental surgery because the relatively small field size of its images limits the patient's exposure to radiation.

Purpose: The aim of this in vitro study of titanium abutments was to investigate the extent of treatment traces, the roughness depth, and the quantity of titanium or, in the case of coated abutments, titanium nitride (TiN) removed from the surface after treatment with various instruments. Materials and Methods: Eleven uncoated, mechanically smoothed abutments and 11 TiN-coated abutments were used. The abutments were treated with titanium, steel, and plastic curettes; a rubber cup; an ultrasonic scaler with a steel tip; and an air scaler and cleaning powder. There were two 2 × 2-mm test fields on each abutment; each was subjected to standardized treatment with an instrument. The untreated surfaces of each abutment served as controls. The roughness depth (Rz) and profile height of treated and untreated surfaces were measured with a profilometer; profile height served as a basis for determining the amount of substance removed by treatment. The treatment traces were analyzed by scanning electron microscopy and light microscopy. Results: Both the ultrasonic scaler and the steel and titanium curettes left pronounced traces on the uncoated abutments and increased Rz. Substantial substance removal was recorded following the use of the ultrasonic scaler (17.57 ± 2.87 µm) and the steel curettes (8.48 ± 2.81 µm) on the uncoated abutments. In tests of the coated abutments, measurable substance removal (4.80 ± 0.99 µm) and increased roughness depth were noted only with use of the steel curettes. The treatment traces left by the other instruments were distinctly less pronounced than on the uncoated abutments. Light microscopy revealed detachment of the TiN coating after use of the ultrasonic scaler, titanium curettes, and steel curettes. Slight to moderate treatment traces were recorded after use of the rubber cup; no substance removal was observed. On the TiN-coated abutments, only slight treatment traces, if any, were recorded, and there was no substance removal. A planing effect (ie, an Rz decrease of 66.4%) was observed. The plastic curette and the air scaler caused no damage to the titanium or TiN surfaces. Discussion and Conclusion: The TiN-coated abutments displayed fewer treatment traces, less roughness depth, and less substance removal after being treated with various instruments. Two concerns, however, are the detachment of the coating after only few actions with steel and titanium curettes or with an ultrasonic scaler with steel tip, and the greater initial roughness depth of coated implants.

Purpose: The trabecular bone patterns in jaws and tooth structure were analyzed using microfocus x-ray computerized tomography (micro-CT), and the usefulness of this method was reported. This study was performed to clarify the accuracy of micro-CT and to determine whether micro-CT could replace bone slice segments as a means for assessment of the accuracy of medical radiography units. In addition, the accuracy of compact CT for dental use (compact CT) was evaluated using the same method. Materials and Methods: Three dried hemimandibles were used in this study. Images of mandibular interdental alveolar bone in the premolar and molar regions were obtained using micro-CT and compact CT. Measurement of the mandibular shape at 6 sites using micro-CT images and at 4 sites using compact CT images was performed, and then the values of the micro-CT and compact CT were compared with those of bone slice segments. Results: The accuracy of mandibular measurement and the ratios of agreement for micro-CT were significantly higher than those for compact CT. Moreover, the coefficient of correlation of the rate of trabecular bone between compact CT images and bone slice segment images was 0.916. Discussion: The significant difference in mandibular measurement betwen micro-CT and compact CT was considered to be related to pixel size. Conclusion: Micro-CT can replace bone slice segments for assessment of the accuracy of medical radiography units. In addition, compact CT can be used for imaging diagnosis in dental implant treatment. It is suggested that the ratio of trabecular bone could be used to evaluate the bone density.

Purpose: This study evaluated the long-term survival and success of different implant-supported prostheses supported by ITI implants. Materials and Methods: Two hundred fifty consecutive patients were rehabilitated using implant-supported prostheses. Seven hundred fifty-nine implants were loaded. Single-tooth prostheses (n = 106), cantilever fixed partial prostheses (n = 42), fixed partial prostheses (n = 137), fixed complete prostheses (n = 5), implant/tooth-supported prostheses (n = 13), and overdentures (n = 37) were used. The mean follow-up period was 3.85 years. Life table analyses were performed. Implant survival rates were calculated by means of standard life table principles. Statistical analysis was performed to compare the implant survival and success by implant placement site for each type of prosthesis. Results: The cumulative implant survival rates were calculated for implants supporting single-tooth prostheses (95.6%), cantilever fixed partial prostheses (94.4%), fixed partial prostheses (96.1%), fixed complete prostheses (100%), implant/tooth-connected prostheses (90.6%), and overdentures (95.7%). Similar survival and success rates were documented for implants placed in maxillae and mandibles. Implant size did not influence survival. Discussion: Seven-year survival rates were similar for implants supporting single-tooth prostheses, cantilever fixed partial prostheses, fixed partial prostheses, and implant/tooth-supported prostheses. Medium-long term implant survival and success were not influenced by the site (maxilla or mandible). Implant and prosthetic survival rates for overdentures supported by 2 implants were comparable to those for overdentures supported by 3 or more implants. Conclusion: Prostheses supported by ITI implants represent a reliable mediumterm treatment. (More than 50 references.)

Purpose: The purpose of this controlled prospective clinical study was to compare cemented and screw-retained implant-supported single-tooth crowns followed for 4 years following prosthetic rehabilitation with respect to peri-implant marginal bone levels, peri-implant soft tissue parameters, and prosthetic complications. Materials and Methods: Twelve consecutive patients were selected from a patient population attending the Implantology Department at the University of Padova. They all presented with single-tooth bilateral edentulous sites in the canine/premolar/molar region with adequate bone width, similar bone height at the implant sites, and an occlusal scheme that allowed for the establishment of identical occlusal cusp/fossa contacts. Each patient received 2 identical implants (1 in each edentulous site). One was randomly selected to be restored with a cemented implant-supported single-tooth crown, and the other was restored with a screw-retained implant-supported singletooth crown. Data on peri-implant marginal bone levels and on soft tissue parameters were collected 4 years after implant placement and analyzed to determine whether there was a significant difference with respect to the method of retention (cemented versus screw-retained). Results: All patients completed the study. All 24 implants survived, resulting in a cumulative implant success rate of 100%. Statistical analysis revealed no significant differences between the 2 groups with respect to peri-implant marginal bone levels and soft tissue parameters. Discussion: The data obtained with this study suggested that the choice of cementation versus screw retention for single-tooth implant restorations is likely not based on clinical results but seems to be based primarily on the clinician's preference. Conclusions: Within the limitations of this study, the results indicate that there was no evidence of different behavior of the peri-implant marginal bone and of the peri-implant soft tissue when cemented or screw-retained single-tooth implant restorations were provided for this patient population.

Purpose: It was the aim of the present study to clinically evaluate the success of osteotome-mediated sinus floor elevation (OMSFE) using autogenous and xenogenic bone and a variety of screw-type implants. Materials and Methods: From August 1995 to February 2003, 276 OMSFE procedures with simultaneous implant placement were completed in 167 patients. Results: The mean residual bone height (RBH) of the alveolar ridge was 7.1 mm (range 3 to 10 mm). The mean increase in height of the implant sites using osteotome techniques was 3.8 mm (range 2 to 7 mm). Of the 276 implants placed, 240 had been loaded for an average of 27.9 months (range 1 to 84 months). There were a total of 18 failures: Ten implants failed to integrate, 3 implants were lost within the first 18 months of loading, 1 implant fractured after 3 years in function, and 4 implants demonstrated excessive bone loss. The overall survival rate was 93.5%. When only sites with an RBH of 4 mm or less were considered, the survival rate dropped to 73.3%. Small tears in the Schneiderian membrane were clinically assessed at 13 sites, for a detectable perforation rate of 4.7%. Discussion: The primary determinant in implant survival with OMSFE procedures was the height of the residual alveolar ridge. Implant design, graft material, and the method of sinus floor infracture (direct or bone-cushioned) exerted minimal influence on survival outcome; however, factors such as edentulism, osteoporosis, and an overdenture prosthesis were shown to negatively influence postloading survival of implants placed in areas of limited RBH. Conclusion: OMSFE procedures can be used predictably for implant placement at sites with moderate vertical deficiencies in the posterior maxilla.

Purpose: The purpose of this study was to evaluate the short-term clinical outcome of single-tooth implants placed in the maxilla and immediately restored using cementless friction-fit temporary crowns. Materials and Methods: Twenty-five patients consecutively referred to a private specialist practice for the replacement of failing or missing maxillary teeth were treated by means of immediate temporization of their single-tooth implants. Where teeth were still present, implants were placed immediately following extraction. Provisional crowns were fabricated on a special friction-fit coping by means of autopolymerizing acrylic resin. Definitive crowns were placed a mean of 4.5 months after surgery. Implant survival was recorded along with the level of the marginal bone relative to a fixed reference point 1 year after placement. Any adverse soft tissue changes were also noted. Results: A total of 28 Astra Tech ST dental implants were placed. The overall survival rate at the end of the study was 96.4% for implants which were in function for periods ranging from 15.7 to 27 months. One patient, a smoker, lost 1 implant within 1 month of surgery. Mean marginal bone loss was 0.40 mm (range 0 to 1.53 mm) 1 year after placement of the implants. Many implants (37.5%) had no observed bone loss. No implants or crowns have been lost during the functional loading period. One implant was associated with an unfavorable recession of soft tissues; however, most maintained an esthetic gingival architecture. Eleven of 28 provisional restorations needed treatment; 6 required replacement during the temporization period, and 5 required cementation because of looseness. The ease of removal of the crowns allowed regular access for irrigation with chlorhexidine and thus maintenance of soft tissue health. Discussion: The need to provide provisional restorations for single-tooth gaps often presents challenges. An immediate temporary partial denture or adhesive prosthesis may be unacceptable or impractical. The current study describes a simple method for the immediate temporization of single-tooth implants. The results did not indicate any negative influence on osseointegration or shortterm survival once the implants were functionally loaded. Conclusion: Immediate temporization of maxillary single-tooth implants can be both safe and predictable, and it appears that the procedure can yield favorable soft tissue esthetics.

This patient report describes the treatment of a 42-year-old woman with cleidocranial dysplasia. Endosseous implants were used to restore the mandibular and maxillary arches with fixed prostheses. Six implants were placed in the mandible and immediately loaded with an acrylic resin fixed prosthesis. In the maxillary arch, 10 implants were submerged for 4 months prior to functional loading. A transitional denture was relined and placed in the maxilla 10 days after implant placement. Three months later, a definitive mandibular prosthesis was fabricated. The definitive maxillary restoration was delivered 6 months after surgery. The most recent follow-up, 6 months after delivery, confirmed a satisfactory treatment result to date.

A 72-year-old male patient with Parkinson's disease referred to the Dental Hospital of Kyushu University, Fukuoka, Japan, presented with movement of an implant-supported prosthesis, slight pain, and purulent drainage from the gingiva in the anterior region of the maxilla, where implants had been placed more than 20 years earlier. He requested that the mobile implant and prosthesis be removed and was in need of implant therapy in his maxilla. In addition to Parkinson's disease the patient had a severe gag reflex, which made treatment difficult. A total of 6 treatments were required. New implants were successfully placed while the patient was under anesthesia (a combination of intravenously administered 3% prilocaine hydrochloride and vasopressin); midazolam was also administered intravenously. The results of this case indicate that use of regional anesthesia in combination with midazolam can be recommended for implant surgery in patients with Parkinson's disease. Intravenous midazolam can be considered the sedative of choice for the surgical treatment of patients suffering from systemic disease.

Although alveolar distraction is a promising method for ridge augmentation involving the atrophic maxilla or mandible for implant placement, techniques of horizontal and oblique alveolar distraction for expanding a narrow alveolar ridge have not been established. A case of horizontal alveolar distraction for implant placement using a titanium mesh plate and a distraction screw is reported. Horizontal alveolar distraction was performed on a patient with an extremely atrophic alveolar ridge in the anterior mandibular region. Two transport segments using horizontal osteotomies were prepared, and 2 horizontal alveolar distraction devices were inserted. After a 7-day waiting period, the devices were activated and alveolar widening was performed labially (0.225 mm twice a day for 14 consecutive days). Three months after consolidation, the distraction devices were removed. The distracted areas were completely filled with newly formed solid bone tissue. Two months after the device was removed, 4 endosseous implants were placed and an implant-supported definitive prosthesis was placed. This method of horizontal alveolar distraction appears to be clinically useful for the placement of implants in atrophic or knife-edged alveolar ridges.

A 56-year-old woman was referred for the treatment of a mandibular lesion that had been slowly increasing in size over a 6-month period. Intraoral examination revealed a reddish-purple nodule involving the attached vestibular gingiva around a machined-surface dental implant that had been placed 2 years earlier in the mandibular left second premolar region. Another implant had been placed in the mandibular left second molar region. The lesion was tender and bled easily upon tooth brushing. Radiographs showed inadequate abutment angulation. The healing caps on these 2 implants were loose and in contact with each other, preventing optimal oral hygiene. An excisional biopsy of the mass resulted in the diagnosis of peripheral giant cell granuloma. After the implants were gently curetted and scaled, they were cleaned using abrasive paste. At the last follow-up, 3 years later, there was no recurrence.