The International Journal of Oral & Maxillofacial Implants, 01/2009

Purpose: This dog study sought to evaluate guided bone regeneration (GBR) in peri-implant defects following implantation of b-tricalcium phosphate (b-TCP) with and without osteoinductive recombinant human growth/differentiation factor-5 (rhGDF-5). Materials and Methods: In five beagle dogs, all mandibular premolars and the first molar were extracted. After 2 months, six buccolingual critical-size defects were created, and an implant was inserted into the center of each defect. One defect was filled with b-TCP coated with rhGDF-5 (600 µg/g b-TCP) and covered with a titanium-reinforced e-PTFE membrane (GDF group). A second defect received the same treatment, but pure uncoated b-TCP was used (TCP group). A third defect was filled with b-TCP mixed with autograft and not protected with a membrane (control group). The remaining three defects were filled with other biomaterials. After 2 months, total new bone area, regenerated bone height, and residual amount of b-TCP were determined histomorphometrically. Results: All implants osseointegrated. One membrane in each group became exposed. Mean new bone area for GDF, TCP, and control sites was 43.9 ± 18.7 mm2, 32.3 ± 16.1 mm2, and 13.1 ± 4.0 mm2, respectively, with a significant difference between GDF and control groups. Mean regenerated bone height was 103.8 ± 29.7%, 75.4 ± 36.6%, and 67.2 ± 19.1% for the GDF, TCP, and control groups, respectively. Mean residual matrix volumes were 25.9 ± 13.6%, 30.0 ± 13.0%, and 13.4 ± 6.5%, respectively. Membrane protection of peri-implant defects filled with b-TCP resulted in a stronger effect on bone regeneration, although this was not statistically significant. The most pronounced regenerative results were achieved in rhGDF-5/b-TCP filled membrane-protected defects. Conclusion: Delivery of rhGDF-5 on b-TCP might have the potential to enhance the results of GBR in peri-implant defects. Keywords: autogenous bone, barrier membrane, b-tricalcium phosphate, dental implants, guided bone regeneration, recombinant human growth/differentiation factor-5

Purpose: Hydrofluoric acid treatment of moderately rough commercially pure titanium produced by titanium oxide (TiO2) grit blasting (OsseoSpeed) results in a surface with nanofeatures. The aim of this project was to better understand the effect of surface nanotopography on adherent osteoblastic differentiation. Materials and Methods: Human mesenchymal stem cells were grown on TiO2 grit-blasted and hydrofluoric acid-treated/TiO2 grit-blasted titanium coins for 1 to 28 days. The nature of the surfaces was evaluated using scanning electron microscopy, optical interferometry, and x-ray photoelectron spectrometry. Osteoblastic differentiation was measured using real-time polymerase chain reaction measurement of more than 80 mineralized tissue-associated, protein-encoding mRNAs. Results: Hydrofluoric acid-treated surfaces displayed nanofeatures of 100 nm in diameter and maintenance of micron-level topography. Adherent cell osteoblastic differentiation occurred on both surfaces but took place more rapidly and to a greater extent on hydrofluoric acid-treated surfaces. This was revealed by earlier, higher, and sustained levels of osteoinductive transcription factors (RUNX-2, SMADs), growth factors (insulin-like growth factor 2, bone morphogenetic proteins), and bone matrix proteins. Conclusions: The superimposition of nanofeatures on a moderately rough commercially pure titanium surface is associated with marked osteoinduction and osteogenesis of adherent mesenchymal stem cells. The role of nanotopography in directing adherent cell behavior should be fully investigated. Keywords: commercially pure titanium, gene expression, human mesenchymal stem cell, nanotopography, osteoinduction, real-time polymerase chain reaction

Purpose: This study aimed to histometrically evaluate the influence of low-intensity laser treatment on bone healing around titanium implants placed in rabbit tibiae. Materials and Methods: Each tibia of 12 adult rabbits received a 3.3 X 6-mm titanium implant. The implants placed in the right tibiae were irradiated with a gallium-aluminum-arsenide diode low-intensity laser every 48 hours for 14 days postoperatively, and the left tibiae were not irradiated. After 3 or 6 weeks, the animals were sacrificed (six animals per period), and nondecalcified sections were obtained and analyzed for bone-to-implant contact (BIC) and bone area within the implant threads. Data were subjected to statistical analysis using analysis of variance (ANOVA) and the Tukey test. Results: BIC was significantly increased in the laser-treated group at both 3 weeks and 6 weeks. BIC did not increase significantly with time (3 weeks versus 6 weeks). Conversely, bone area within the threads was significantly increased with time (3 weeks versus 6 weeks), regardless of whether the laser was used. Considering bone area within the threads, no significant difference was found for treatment, eg, with or without laser. Conclusion: Low-intensity laser therapy did not affect the area of bone formed within the threads, but it may improve BIC in rabbit tibiae. Keywords: bone healing, dental implants, low-intensity laser therapy

Purpose: To evaluate in vivo collagen fiber behavior around two different dental implant necks placed in the mandibular bone of adult pigs. Materials and Methods: Scanning electron microscopic (SEM) and profilometric analyses were performed on both types of implant necks to evaluate the different surface morphology. Ten dental implants with machined titanium necks and 20 implants with zirconia necks were inserted into the mandibles of five adult pigs. Three months later, the animals were sacrificed; samples from the peri-implant mucosa were obtained and prepared for histologic analysis. Evaluation of collagen fiber orientation in the connective tissue surrounding the implant necks was performed by polarized light microscopy. Inflammation in the peri-implant soft tissues was also measured via the Gingival Index. Results: Postoperative healing was uneventful; all implants, except for one of each type, were osseointegrated after 3 months. SEM and profilometric analyses confirmed that zirconia necks showed Ra, Rq, and Rz values that were lower than those seen around the titanium necks. Histologic observation indicated that collagen fiber orientation was similar for both types of implants. The majority of fibers showed a parallel or parallel-oblique orientation to the implant surface for all samples. Implants that were not osseointegrated, as determined by clinical evaluation, showed inflammatory infiltrate, whereas healthy connective tissue was found around all the other implant necks. Conclusions: Collagen fiber orientation was similar, regardless of implant material, demonstrating a predominantly parallel or parallel-oblique pattern. Moreover, zirconia, which is used as a transgingival collar on some implants, showed connective tissue adhesion that was similar to that seen on the machined titanium surface, but demonstrated limited plaque formation and may provide better esthetics. Keywords: collagen fiber orientation, dental implants, machined titanium neck, zirconia neck

Purpose: To examine the relationship between bone quality, as evaluated by cone-beam computerized tomography (CBCT), and implant primary stability, as measured by resonance frequency analysis (RFA). Materials and Methods: A preliminary clinical study was conducted in which implant placements were scheduled for 20 patients. The CT scan was obtained after initial drilling, and implant stability was measured with the OsstellTM Mentor instrument before flap closure. With CBCT, CT numbers of surrounding bone were calculated and the thickness of compact bone was measured at the buccal, lingual, mesial, and distal surfaces of each implant. The correlations between CT numbers and implant stability quotients (ISQs) and between compact bone thickness and ISQs were tested with the Pearson correlation coefficient. Results: Overall, 61 implants were examined in 20 patients. The statistics showed that the CT numbers and the thickness of compact bone had strong correlations to ISQs (P < .025). Conclusion: CT scanning was suggested to be effective for evaluating bone quality and predicting initial implant stability. Keywords: bone quality, compact bone, computerized tomography, implant stability, resonance frequency analysis

Purpose: Recent research has demonstrated that modification of implant surface chemistry can influence osseointegration events, leading to increased bone-to-implant contact at earlier times. Clinical studies have been initiated to investigate the potential of modified surfaces to reduce the needed healing period between surgery and prosthesis insertion. The purpose of this prospective clinical study was to evaluate the clinical outcome after 3 weeks of loading single implants with hydrophilic surfaces in the maxillary molar areas. Materials and Methods: This prospective two-center clinical trial consecutively included healthy patients who needed an implant in the maxillary molar areas. Drilling was limited to the minimum, most of the site preparation was produced with osteotomes, and screw tapping was never performed. Abutment connection was carried out at 15 Ncm, at 21 (± 2) days after surgery, and provisional restorations were fabricated in occlusion. Further abutment tightening at 35 Ncm was performed after 4 to 6 additional weeks, for the definitive restoration. Results: Thirty-five patients were treated. No major adverse events were registered during and/or after surgery. Primary stability was always achieved. At abutment connection, six of the 35 patients reported minor pain, and placement of provisional restorations was postponed for 4 additional weeks. Clinical and radiographic measures were taken at baseline (abutment connection) and at the 1-year follow-up appointment. No patients dropped out, and no implant losses were registered during the first 12 months of observation. No significant differences between baseline and the 1-year examination were recorded for any outcome measure. Conclusions: These results suggest that, by means of the surgical and restorative technique presented, surface-modified hydrophilic implants are suitable for loading at 3 weeks in maxillary molar areas. Keywords: dental implants, early loading, healing time, osseointegration, osteotome technique, posterior maxilla

Purpose: To investigate the effects of resorbable membrane on new bone formation in human maxillary sinus graft using anorganic bovine bone material histomorphometrically in a split-mouth study design. Materials and Methods: This prospective pilot study included six patients who required bilateral sinus augmentations prior to implant treatment. Each patient was grafted with anorganic bovine bone (Bio-Oss). The experimental side was covered with resorbable membrane (Bio-Gide) over the grafted sinus, and the control side was left uncovered. After 8 months of healing (range, 7 to 9 months), implants were placed. Biopsy samples were obtained from each side through the previously grafted sinus window and evaluated. Statistical analysis was performed using the Mann-Whitney U test at a significance level of alpha = .05. Results: The control side appeared to have a significantly greater amount of soft tissue than the experimental side (P = .026), whereas no significant differences in the amount of new bone were observed (P = .937). Conclusion: Resorbable membranes significantly reduced the amount of soft tissue formed in the sinus grafted with anorganic bovine bone material but had no effect on new bone formation. Keywords: anorganic bovine bone, biopsy, histomorphometry, maxillary sinus

Purpose: Soft tissue closure is mandatory for optimal healing of extraction sites treated via guided bone regeneration. The objective of this study was to evaluate the efficacy of a flap design based on the extension of palatal tissues to obtain and maintain soft tissue coverage over grafted extraction sockets. Materials and Methods: Adult patients (n = 22) with at least two teeth indicated for extraction were treated. After atraumatic extraction, control sockets were filled with a composite graft (1:1) containing demineralized freeze-dried bone allografts and Bio-Oss. Experimental sockets were treated identically, except that an Atrisorb absorbable barrier membrane was also placed over the graft material before flap closure, which was obtained, in all sockets, by the coronal extension of a vascularized pedicle dissected from the periosteal aspect of the palate. Results: Primary tension-free wound closure was achieved at all treated sites. Exfoliation of the graft material during healing was not observed in either treatment group. High levels of soft tissue closure were maintained throughout the study period for both treatment groups, and membrane exposure was observed in only 7% of treated sites. Conclusion: On the basis of this study it appears that the reported technique was an adequate method of achieving and maintaining complete soft tissue coverage and promoting healing by primary intention in grafted extraction sockets in humans. Keywords: bone graft, dental implants, guided bone regeneration

Purpose: To quantitatively evaluate the combined influence of implant diameter and alveolar ridge width on crestal bone stress. Materials and Methods: ITI solid-screw implants, 10 mm in length and 3.3, 4.1, and 4.8 mm in diameter, and the alveolar bone were modeled using axisymmetric finite elements. Four different alveolar ridge geometries were selected for each implant: 5-, 6-, 7-, and 8-mm-wide ridges for the 3.3-mm implants; 6-, 7-, 8-, and 9-mm-wide ridges for the 4.1-mm implants; and 7-, 8-, 9-, and 10-mm-wide ridges for the 4.8-mm implants. A nonaxial oblique load of 100 N was applied at 30 degrees to the implant axis. Regression analysis was used to avoid ambiguity when estimating the peak stress occurring at the coronal contact point between the implant and the crestal bone, ie, the singularity point. Results: Peak stresses were dependent on both implant diameter and alveolar ridge width. Substantially lower stresses were recorded around the implants placed in narrower ridges. Conclusion: A regression analysis may be used to quantify the peak stress at the singularity point. An implant with a diameter that is at least half the ridge width is recommended to reduce the stress concentration in the crestal bone. Keywords: alveolar ridge width, crestal bone stress, finite element simulation, implant diameter, stress singularity, structural rigidity

Purpose: To provide a detailed presentation of computer-aided design/computer-assisted manufacture guidance in severely resorbed posterior maxillae to place implants in a very limited amount of bone, thus avoiding sinus grafting. Materials and Methods: Based on computerized tomography (CT) axial images, implant positions are planned using imaging software. A surgical template is fabricated and drilled with a numerically controlled machine to transfer the planned positions to bone with high accuracy. To avoid sinus grafting, implants can be planned in the anterior or posterior wall and in the septa of the sinus as well as in the palatal curvature. Recipient site preparation is done transgingivally with a drill or with a dedicated bone spreader to increase the amount of bone when necessary. Results: Fifteen resorbed posterior maxillae were treated with a fixed prosthesis supported by a combination of 42 upright and tilted implants. In all cases, implants were placed as planned. Seventeen implants were tilted at a 20- to 35-degree angle with the line perpendicular to the axial CT images. Seven implants were placed in the palatal curvature, 11 implants were close to the anterior wall, and two of them in combination with the palatal curvature. Only one implant was placed close to the posterior wall and two were placed in septa. All patients attended scheduled follow-up visits. During the 4-year observation period, no complications were recorded, no implants were lost, and there was no infection or inflammation. Conclusion: This proof-of-concept study suggests that the use of an image-guided system associated with bone spreading for oral implant placement in the atrophic posterior maxilla can be an alternative to sinus grafting. Keywords: atrophic maxilla, bone graft, bone spreading, computer-aided surgery, implant dentistry, maxillary sinus, minimally invasive surgery, surgical flap, tilted implants, x-ray computerized tomography

Purpose: The purpose of the present investigation was to clinically assess and compare crestal bone changes, over a 5-year period, around external-hexagon wide-diameter implants restored with either matching wide-diameter prosthetic components or with platform-switched prosthetic components. Materials and Methods: During the years 2000 to 2002 all patients who received a single 5-mm-diameter implant with an external hexagon in a private office setting were included in this study. All implants were placed in the posterior areas of the jaws. Maxillary left molars (group A1) and mandibular right molars (group A2) were restored with matching wide-diameter prosthetic components; maxillary right molars (group B1) and mandibular left molars (group B2) were restored with platform-switched prosthetic components. Marginal bone resorption was measured via intraoral radiographs each year after abutment and crown insertion. Statistical analyses were used to determine whether there was a significant difference in marginal bone levels with respect to the width of prosthetic components used. Results: In all, 182 single 5-mm-diameter implants were placed in 144 patients and all implants survived. Eighty-five implants were restored with matching wide-diameter prosthetic components (group A), and 97 implants were restored with platform-switched prosthetic components (group B). A significant difference in marginal bone levels was found between group A and group B implants after 1 year. The mean marginal bone resorption was 0.9 mm (SD 0.3 mm) for group A implants and 0.6 mm (SD 0.2 mm) for group B implants. Marginal bone resorption observed at the second, third, fourth, and fifth years after abutment and crown insertion did not show any significant change. Conclusion: Statistically significant differences in marginal bone loss were observed between study groups. The 85 implants restored with matching wide-diameter prosthetic components showed more bone loss than the 97 implants restored with platform-switched prosthetic components. Keywords: dental implants, implant diameter, platform switching

Purpose: To evaluate the effect of oral rehabilitation with immediately loaded fixed implant-supported mandibular prostheses on chewing and swallowing in elderly individuals. Materials and Methods: Fifteen completely edentulous patients aged more than 60 years (10 women and five men), wearing removable dentures in both arches, had a mandibular denture replaced by an implant-supported prosthesis. All individuals were evaluated before surgery and again 3, 6, and 18 months later with regard to mastication and swallowing conditions. Examinations entailed an interview, evaluation of tactile sensitivity of the face, and observation of food intake, masticatory type, formations of bolus, and pain during mastication. The swallowing evaluation comprised observation of clinical signs related to the oral and pharyngeal stages of swallowing, as well as the presence of oral residue. The findings of different evaluations before and 3, 6, and 18 months after the surgical-prosthetic procedure were statistically compared by analysis of variance for repeated measurements at a significance level of 5%. Results: The questionnaire revealed a reduction in complaints of masticatory and swallowing disturbances, a decreased need for liquid ingestion, and reduced choking and coughing. Clinical evaluations showed improved oral function and bolus propulsion for both solid and paste-consistency foods; pain during mastication was also resolved. Conclusion: Treatment with mandibular implant-supported dentures had positive effects on the clinical aspects of mastication and swallowing in elderly individuals. Keywords: complete denture, elderly, implant-supported prostheses, mastication, swallowing

Purpose: To report the use of a new platelike system (Titanium Epiplating System, Medicon, Tuttlingen, Germany) for rehabilitation of patients after total rhinectomy. Materials and Methods: This retrospective study was conducted on all patients treated between August 2001 and July 2006 with total or subtotal rhinectomy. The clinical outcomes and satisfaction of patients receiving nasal prostheses were evaluated, and the success rate of the subperiosteal implants was determined. Quality of life (QOL) was evaluated with a standardized questionnaire. Patients who had experience with different retention methods responded to a five-point scale evaluating their current satisfaction. Results: Eleven patients (four women and seven men) received nasal prostheses. The mean age was 63 ± 12 years (range, 43 to 84 years). Nine patients were fitted with subperiosteal microplates and followed for a mean of 35 months. Two patients had subtotal rhinectomy and did not receive implants. In four patients immediate implant placement (concurrent with tumor resection) was performed; the other five patients received implants later. The implant success rate was 82%. There was no early implant loss, although one patient lost his implants after 3 years and another patient lost one implant after 1.5 years. QOL scores demonstrated high acceptance of implant fixed retention in comparison with other retention methods (P = .001). Conclusions: Implantation of anatomically prefabricated titanium plates has a high success rate in the nasal area, although late implant loss may occur. Patient perceptions of QOL show improvement when prostheses are retained by subperiosteal implants. Keywords: platelike systems, prosthetic rehabilitation, quality of life, rhinectomy

Recently, computer technology has made it possible to simulate implant placement, fabricate a precise surgical template based on the simulated implant locations, and fabricate a prosthesis prior to surgical placement of implants. Many successful patient treatments have been reported using this process, but little has been published regarding complications. This article reports on the misfit of an immediately loaded definitive fixed complete denture that had been fabricated prior to implant surgery. The prosthesis was designed and fabricated using computerized implant data. A surgical template was fabricated (Nobel Guide) from the computer data to guide implant placement using an "All-on-Four" design concept. Management of the prosthesis misfit is discussed along with subsequent clinical complications. Keywords: all-on-four, computer-guided surgery, dental implants, fixed complete denture, immediate loading, misfit, nobel guide

Purpose: This article describes a series of patients who underwent calvarial bone grafting (CBG) for reconstruction of extremely edentulous jaws for the purpose of implant placement. Materials and Methods: A retrospective review was conducted of all patients treated with split CBGs to the atrophic maxilla or mandible between 1999 and 2006. All patients were monitored for signs of infection, dehiscence, or other complications. The amount of augmentation was measured on panoramic radiographs. Results: A total of 15 reconstructed sites (eight maxillary, seven mandibular) in 13 consecutive patients with a mean preoperative height of 6 mm (range, 3 to 9 mm) were included in the study and followed for a mean of 32 months. Ten women and three men aged 40 to 88 years (mean, 63 years) underwent surgery. There were no complications associated with the bone harvesting technique, and all implants had primary stability at the time of placement. Two patients had graft exposure in the maxilla. Two implants were removed in one patient. On average, the gain in ridge height was 15 mm (range, 10 to 19 mm). A total of 53 implants were placed, with an average of four implants per patient. Conclusion: Split CBGs to the atrophic maxilla and mandible can restore optimal height to support and facilitate implant-based restorations. A prospective study with a longer follow-up period is required to evaluate the rate of resorption associated with split CBG. Immediate placement of implants at the time of grafting in the mandible shortens the treatment time. Keywords: alveolar ridge resorption, cranial bone grafting, implant reconstruction

Successful implant treatment includes osseointegration, as well as prosthetically optimal positions of the implants for esthetics and function. The aim of this study is to evaluate a patient that was treated with an implant-supported fixed prosthesis with the help of computer-assisted three-dimensional planning. A 52-year-old edentulous man underwent computerized tomographic (CT) scanning, and the cross sections were reformatted. The cross sections were used to construct a surgical guide. Eight ITI Straumann dental implants were placed using a series of supramucosal surgical stents. Following a 5-month healing period, the stability of the implants was confirmed with the use of an Osstell device. Because satisfactory stability was observed, implant-supported fixed partial dentures, incorporating 12 units in all, were made. After 6 months, a second CT evaluation was carried out and the positions of the implants were compared with the treatment planning data. The CT-based software program and surgical stents contributed to the success of this case. Keywords: computerized tomography-based software, dental implant, flaples surgery, implant dentistry

Mandibular fractures in association with the insertion of endosseous dental implants have been reported in the literature. In this clinical case report, the nonsurgical management of a mandibular fracture with the use of a bar restoration is described and a 3-year follow-up is presented. The options for nonsurgical treatment are discussed. Keywords: complications, fracture, mandible

Ectodermal dysplasia (ED) is a genetic disorder that is often associated with anomalies of teeth such as hypodontia and oligodontia. Individuals affected by ED have abnormalities of the epithelial tissue of the hair, nails, teeth, or sweat glands. Implant-prosthetic rehabilitation is often necessary because the severity of disease may limit other treatment options. This is a report of a 30-year-old man affected by ED who exhibited severe hypodontia and atrophy of the jaws. Radiographic and clinical evaluations showed inadequate quantity of bone for immediate implant rehabilitation. Osteogenetic vertical distraction and grafting of autogenous bone were performed to obtain the correct bone volume, and implants were inserted in the anterior mandible to support a prosthetic restoration. Keywords: bone distraction, dental implants, ectodermal dysplasia, onlay grafting

Hopeless retained primary teeth without permanent successors represent a restorative challenge for clinicians, along with esthetic and functional problems for patients. While various treatment approaches for congenitally missing teeth have been proposed, the replacement of a missing tooth with a dental implant offers specific advantages, such as preservation of the alveolar crest and elimination of the need to restore the adjacent teeth, over other options for tooth replacement. The aim of this article was to illustrate the surgical and prosthetic treatment with implants of a patient with primary teeth without permanent successors. Keywords: dental implants, immediate function/loading, immediate implants

Purpose: Some variations of the mandibular canal (so-called bifid mandibular canal) have been reported using various radiography techniques; however, the occurrences of bifid mandibular canal were less than 1% according to panoramic radiographic surveys. The purpose of the present investigation was to clarify the rate and type of bifid mandibular canal in the mandibular ramus region, as observed using cone-beam computerized tomography (CBCT) images. Materials and Methods: One hundred twenty-two patients who had undergone preoperative imaging of dental implant treatment using CBCT were enrolled in the investigation. Two-dimensional (2D) images of various planes in the mandibular ramus region were reconstructed on a computer using three-dimensional visualization and measurement software. The course of the mandibular canal was observed and the length of the bifid canal was measured. Results: Bifid mandibular canal in the mandibular ramus region was observed in 65% of patients and 43% of sides. Bifid mandibular canal can be classified into four types: retromolar, dental, forward, and buccolingual canals. Conclusion: Bifid mandibular canal was observed at a high rate using CBCT. Keywords: bifurcation, cone-beam computerized tomography, dental implant, mandibular