The International Journal of Oral & Maxillofacial Implants, 06/2006

Purpose: The influence of thin carbonate-containing apatite (CA) coating on the trabecular bone response to titanium implants was investigated. Materials and Methods: Thin CA coatings were deposited by a new method known as the molecular precursor method. Using a precursor solution composed of an EDTA-calcium complex, a CA film was deposited on the titanium surfaces. Uncoated and CA-coated titanium were placed in the trabecular bone of the left and right femoral condyles of 16 rabbits. After implantation periods of 2, 4, 8, and 12 weeks, the bone-implant interface was evaluated histologically and histomorphometrically. Results: Histologic evaluation revealed new bone formation around the uncoated and CA-coated implant surfaces after only 4 weeks of implantation. After 12 weeks, mature trabecular bone surrounded all implants. At 4 and 8 weeks of implantation, no difference existed in bone contact between uncoated and CA-coated implants. After 12 weeks of implantation, the CA-coated implant group showed a significantly higher percentage of bone contact than the uncoated implant group. Discussion and Conclusion: The present study demonstrated that thin CA coatings applied using the molecular precursor method showed greater bone-to-implant contact during the healing phase than uncoated controls. The results were similar to those observed with implants with calcium phosphate coatings. Keywords: dental implants, facial prostheses, magnets, maxillary obturators, milled bar attachments

Purpose: The synergistic effect of fibroblast growth factor (FGF) and human fibronectin fragment (hFNIII9-10) on osteoblast cell adhesion has been demonstrated in vitro. The purpose of this study was to evaluate the bone response around anodized titanium implants treated with FGF-FN fusion protein using the histomorphometric analysis and the removal torque test. Materials and Methods: Threaded implants were manufactured by machining a commercially pure titanium (grade 4). Two different groups of samples were prepared: Group 1 samples were anodized under a constant voltage of 300 V, and group 2 samples were anodized under a constant voltage of 300 V and then soaked in a solution containing fusion protein (65 µg/mL) for 24 hours. Ten implants from each group were placed in rabbit tibiae (1 implant per group per rabbit; each rabbit served as its own control). After a 3-month healing period, the animals were sacrificed. Removal torque testing and histomorphometric analysis was then carried out. Results: The mean removal torque value of group 2 (44.8 Ncm) was greater than that of group 1 (37.6 Ncm). The percentages of bone-implant contact of the best 3 consecutive threads were 76.37% for group 1 and 88.02% for group 2. The percentage of bone-implant contact for the total length of the implant was higher for group 2 (36.91%) than for group 1 (29.47%). However, the percentage of the area inside the threads that consisted of bone did not differ significantly for the 2 groups. Discussion and Conclusion: This study demonstrated that the FGF-FN fusion protein coating on anodized implants may enhance osseointegration. However, the influence of fibronectin- and FGF-treated rough surfaces on long-term prognosis and the propagation of inflammation are subjects for further study. Keywords: alveolar process, dental esthetics, dental implants, facial growth, jawbone, orthodontics, puberty

The replacement of teeth lost by children because of trauma can be an important indication for early implant therapy. Osseointegrated dental implants, like ankylosed teeth, alter position as growth-related changes occur within the jawbones (displacement, remodeling, mesial drift). Facial growth of the child and even of the adolescent, as well as the continuous eruption of the adjacent anterior teeth, create significant risk of a less favorable esthetic and/or functional outcome. For patients with a normal facial profile, the placement of an implant should be postponed until growth is complete. For patients with a short or long face type, further growth, especially the continuous eruption of adjacent teeth, creates a serious risk even after the age of 20 years, as illustrated by some recent clinical studies. This review aims to explain these phenomena and provides some recommendations for implant placement. Keywords: alveolar process, dental esthetics, dental implants, facial growth, jawbone, orthodontics, puberty

Purpose: A 3-dimensional finite element model was developed to investigate the cause of different crestal bone loss patterns observed around sintered porous-surfaced and machined (turned) threaded dental implants used for orthodontic anchorage in a previously reported animal study. Materials and Methods: Twenty-noded structural solid elements with parabolic interpolation between nodes were used for modeling the bone-implant interface zone. A 3-N traction force acting between either 2 porous-surfaced or 2 machined threaded implants placed in canine premolar mandibular sites and bone profiles observed at initiation and 22 weeks of orthodontic loading were modeled. Results: Higher maximum stresses in peri-implant bone next to the coronal region of the implants were predicted with the machined threaded implants at both the initial and final time points, with the values 20% greater than those predicted after the 22-week loading period. These values were approximately 200% greater than those predicted for the porous-surfaced implants, for which a more uniform stress distribution was predicted. Discussion: The finite element model results indicated that the observed greater retention of crestal bone next to the porous-surfaced implants was attributable to lower peak stresses developing in crestal peri-implant bone with this design, which decreased the probability of bone loss related to local overstressing and bone microfracture. Conclusion: The predicted lower stresses were a result of the more uniform transfer of force from implant to bone with the porous-surfaced implants, which was a consequence of the interlocking of bone and implant possible with this design. Keywords: alveolar process, dental esthetics, dental implants, facial growth, jawbone, orthodontics, puberty

Over the last few decades, reconstructive surgery has shifted from a resection-oriented approach toward strategies focusing on repair and regeneration of tissues. As the main aim of maxillofacial reconstruction has been the restoration of bone form and function, surgeons used artificial tissue substitutes in the early decades of bone reconstruction. These artificial materials significantly improved the ability of surgeons to restore the form and, to some extent, the function of defective bones. Despite the fact that every artificial material has specific disadvantages, the use of biomaterials is a common treatment option in clinical practice even today. Due to the more detailed understanding that exists concerning transplantation of cells and tissues, autogenous grafts are the second mainstay in clinical practice. However, the main disadvantage of using autogenous grafts is donor site morbidity and donor shortage. Research is currently in progress into the use of cell-based approaches in reconstructive surgery, since cells are the driving elements for all repair and regeneration processes. Various cell populations have been reported on in the relevant literature. These cells can be classified according to differentiation capacity and the tissue from which they originated. In this review, unrestricted cells, multipotential progenitor cells, determined cells, and genetically modified cells are described systematically, and their advantages as well as limitations are discussed. (More than 50 references.) Keywords: alveolar process, dental esthetics, dental implants, facial growth, jawbone, orthodontics, puberty

Cell-based bone tissue engineering is a rapidly evolving therapy option in bone reconstruction strategies. Some cell-driven approaches, especially the biophysical stimulation of the host cell population surrounded by the bone defect, are common treatment methods in maxillofacial surgery. Others, such as autologous cell implantation, have now gained acceptance for clinical trials. More advanced or complex therapeutical options (extracorporeal tissue engineering, stem cell use, genetic engineering) have been tested in preclinical investigations but have not reached the level of clinical use. Two different aspects are of special relevance in cell-based bone reconstruction therapies. The source of cells used to regenerate bone (discussed in detail in a complementary review in this issue of The International Journal of Oral and Maxillofacial Implants) as well as the principal approach of a cell-driven bone regeneration therapy influence the outcome of such engineering strategies. All of the cell-driven repair strategies are under intensive investigation in an effort to provide surgeons with a limitless supply of tissue for bone repair and reconstruction in future procedures. An overview of the basic biological aspects as well as the inherent constraints of different cell-based approaches are given in this paper. (More than 50 references.) Keywords: alveolar process, dental esthetics, dental implants, facial growth, jawbone, orthodontics, puberty

Purpose: This study was intended to calculate the augmentation volume for a sinus lift procedure based on cross-sectional computerized tomography (CT) scans for 2 different augmentation heights. Materials and Methods: Based on area calculations of cross-sectional CT scans, the volume of additional bone needed was calculated for 44 sinus lift procedures. The amount of bone volume needed to raise the sinus floor to heights of both 12 and 17 mm was calculated. Results: To achieve a sinus floor height of 12 mm, it was necessary to increase the height by a mean of 7.2 ± 2.1 mm (range, 3.0 to 10.5 mm), depending on the residual ridge height; to achieve a height of 17 mm, a mean of 12.4 ± 2.0 mm (range, 8.5 to 15.5 mm) was required (P < .01). The calculated augmentation volume for an augmentation height of 12 mm was 1.7 ± 0.9 cm3; for an augmentation height of 17 mm, the volume required was 3.6 ± 1.5 cm3. Increasing the height of the sinus lift by 5 mm, ie, from 12 mm to 17 mm augmentation height, increased the augmentation volume by 100%. A significant correlation was found between augmentation height and the calculated sinus lift augmentation volume (r = 0.78, P < .01). Discussion and Conclusion: Detailed preoperative knowledge of sinus lift augmentation volume is helpful as a predictive value in deciding on a donor site for harvesting autogenous bone and on the ratio of bone to bone substitute to use. Calculation of the augmentation size can help determine the surgical approach and thus perioperative treatment and the costs of the surgery for both patients and clinicians. (Basic Science) Keywords: alveolar process, dental esthetics, dental implants, facial growth, jawbone, orthodontics, puberty

Purpose: The aim of the present clinical trial was to evaluate the 12-month success rate of titanium dental implants placed in the posterior mandible and immediately loaded with 3-unit fixed partial dentures. Materials and Methods: Patients with missing mandibular premolars and molars were enrolled in this study. To be included in the study, the implants had to show good primary stability. Implant stability was measured with resonance frequency analysis using the Osstell device (Integration Diagnostics). Implants were included in the study when the stability quotient (ISQ) exceeded 62. Clinical measurements, such as width of keratinized tissue, ISQ, and radiographic assessment of peri-implant bone crest levels, were performed at baseline and at the 12-month follow-up. The comparison between the baseline and the 12-month visits was performed with the Student t test for paired data (statistically significant at a level of a = 0.05). Results: Forty implants with a sandblasted, large grit, acid-etched (SLA) surface (Straumann) were placed in 20 patients. At 12 months, only 1 implant had been lost because of an acute infection. The remaining 39 implants were successful, resulting in a 1-year success rate of 97.5%. Neither peri-implant bone levels, measured radiographically, nor implant stability changed significantly from baseline to the 12-month follow-up (P > .05). Discussion: The immediate functional loading of implants placed in this case series study resulted in a satisfactory success rate. Conclusion: The findings from this clinical study showed that the placement of SLA transmucosal implants in the mandibular area and their immediate loading with 3-unit fixed partial dentures may be a safe and successful procedure. (Case Series) Keywords: alveolar process, dental esthetics, dental implants, facial growth, jawbone, orthodontics, puberty

Purpose: Evaluation of prosthetic complication was performed on 236 patients treated with 528 implants in an 8-year private practice experience. Materials and Methods: The study sample included 55 overdentures (ODs) and 265 fixed partial dentures (FPDs). Among the latter, 231 FPDs were cemented and 34 were screw-retained. The type and frequency of prosthetic incidents were recorded, including adjustments and complications. Statistical analysis was performed using a chi-square test to identify risk factors associated with complications. Results and Discussion: Over this period, 1 abutment fractured and 2 became loose, leading to a cumulative implant component success rate of 99.2%. Patients with removable prostheses had more complications than those with fixed ones, 66.0% versus 11.5%; the difference was significant (P < .001). Posterior fixed prostheses had more complications than anterior ones, 11.0% versus 0%; however, the difference was not significant (P = .16). The complication rates for cemented and screw-retained prostheses did not differ significantly (10.4% versus 5.9%; P = .61). Prostheses with an extension cantilever had more complications, 29.4% versus 7.9%; the difference was significant (P = .01). In the OD group, the ball-retained prostheses had a significantly higher rate of complications than the bar-retained ones (77.5% versus 42.9%; P = .04). In the FPD group, complications were not recurrent; most occurred during the first 2 years, and the rate of complications did not increase with time. In the OD group, 1.3 incidents per prosthesis were recorded. Incidents were often recurrent, and the rate of complications did not decrease with time. Conclusions: Removable and fixed prostheses were associated with complications at different frequencies and of different types. In the removable group, adjustments and foreseeable complications were numerous, recurrent, and usually easy to manage. Bar-retained prostheses had fewer complications than ball-retained ones. In the fixed group, complications were limited in number and did not increase with time. Complications were restricted to the posterior region. (Case Series)

Purpose: This study investigated the load fatigue performance of narrow-, regular-, and wide-diameter CeraOne (Nobel Biocare) single-tooth implants and abutments. Materials and Methods: Five samples of each implant-abutment combination in 3 different widths were tested at 3 applied screw torque levels (recommended torque, recommended torque +20%, and recommended torque -20%). A rotational load fatigue machine was used to apply a 21-N load, at an angle of 45 degrees to the long axis of the specimens. This loading produced an effective bending moment of 35 Ncm at the abutment-implant interface. An upper cyclic limit was set at 5 3 106 load cycles for all specimens. Results: Two-way analysis of variance revealed a significant difference between narrow-diameter and wide-diameter implant test groups but no significant difference between the 3 torque levels for each implant diameter. In the narrow-diameter group, 6 of the 15 specimens failed (5 abutment screw failures and 1 implant failure). In the regular-diameter group, 3 of the 15 specimens failed (2 implant failures and 1 abutment screw failure). There were no failures in the wide-diameter group. Discussion: The results of this study indicate that the abutment screw is not the only potential failure location. The possibility of implant fracture clinically has been previously reported for prostheses supported by both single- and multiple-implant prostheses. Conclusion: The wide-diameter CeraOne single-tooth implant system demonstrated superior load fatigue performance. For clinical situations with significant functional loading, the narrow-diameter implants would be at a greater risk of fatigue failure. (Basic Science)

Purpose: In many edentulous maxillae, posterior alveolar atrophy calls for bone grafting. Patient treatment acceptance is increased by eliminating grafting using tilted implants, especially the zygomatic implant in combination with immediate function. The purpose of this study was to evaluate a protocol for immediate function (within 2 hours) of 2 zygomatic and 4 standard implants (Nobel Biocare) supporting a fixed prosthesis in the completely edentulous maxilla. Materials and Methods: This clinical study included 14 patients with 83 immediately loaded implants (28 bilateral zygomatic and 55 premaxillary implants) supporting a complete maxillary denture converted to a fixed provisional prosthesis immediately following the surgical procedure. After 6 months of use, a new fixed metal-supported prosthesis was fabricated. Results: Fourteen patients treated with immediate loading of zygomatic implants were followed for at least 12 months. All patients reported minimization of postoperative pain and security during speech, animation, and mastication. No failures occurred during the follow-up period. Discussion: The patients in the study could have been candidates for sinus grafting. With the present concept these patients benefited from a less invasive procedure (1 surgical procedure and no grafting) and immediate rehabilitation (prosthesis attached directly after surgery). Conclusion: The high survival rate, increase in patients' immediate functional ability, and reduction of morbidity following the surgical procedure render this procedure a viable treatment option for the completely edentulous maxilla. (Case Series)

Purpose: This study investigated pain experience and anxiety following dental implant placement using questionnaires and salivary cortisol measurements. Materials and Methods: Patients about to undergo implant placement were instructed to keep recovery diaries to assess pain experience (limitation of activities, postoperative symptoms) and to record average pain, worst pain, and interference with daily activities on a visual analog scale (VAS). To assess anxiety, patients completed the Spielberger self-evaluation questionnaire and collected salivary samples to measure cortisol levels. Saliva was collected 1 week before surgery, the day of surgery, and 3 and 6 days postoperatively. A repeated-measure analysis of variance was used to analyze pain and anxiety data. Results: Eighteen patients (12 women and 6 men) who received 30 implants were recruited for the study. Following implant placement, most patients reported mild to moderate interference with daily activities and postoperative symptoms. No patient reported high levels of any symptom. Average pain experience decreased significantly with time (F = 6.17; P < .001), from a VAS score of 24/100 on day 1 to 12 on day 3 and 9 on day 6. Worst pain (F = 7.84; P < .001) and limitation of daily activities (F= 6.26; P < .001) were also highest on the first postoperative day; they also decreased to about half the maximum level by the second or third day. State anxiety, as evaluated by the Spielberger self-evaluation scale, was highest on the day of surgery. The salivary cortisol level did not validate this, as it did not differ with the time of collection (F = 2.22; P = .075). Conclusions: Patient self-assessment indicates that implant placement is a mild to moderately painful and anxiety-provoking procedure. Some limitation of daily activities and symptoms are expected to occur, particularly during the first 3 postoperative days. (Case Series) Keywords: anxiety, dental implants, pain, questionnaires, salivary cortisol

Purpose: Since 1997, the use of highly active antiretroviral therapy (HAART) has significantly improved systemic health and life expectancy of patients who test positive for the human immunodeficiency virus (HIV) in industrialized countries. Therefore, although implant-supported prosthetic rehabilitation has been restricted to immunocompetent individuals, it may be considered for these patients. Case Reports: The treatment course of implant-prosthetic rehabilitation in 3 patients is reported. Patient 1 (male, age 64 years) was under 4-drug therapy; patient 2 (male, age 38 years) and patient 3 (female, age 49 years) were under 3-drug therapy. Two patients had suffered from AIDS-defining diseases prior to HAART. Oral manifestations of HIV infection were not diagnosed throughout the observation period. Patients had CD4+ cell counts between 250 and 800/mL, and viral load was below 50/mL. Perioperative antibiotic treatment was not applied. Two patients presented with edentulous mandibles. In the third patient, single-tooth replacement of both mandibular first molars was performed. A total of 10 Frialit-2 implants were placed without augmentation procedures. Results: One implant failed after 3 months and was successfully replaced. Two patients received magnet-retained overdentures in the mandible, and 1 patient was treated with single crowns. All implants and restorations are successfully in function. Neither radiographic nor clinical signs of inflammation were detected during the observation period (range, 7 to 32 months). Conclusions: The outcomes of the 3 patients suggest that immunologically stable HIV-positive patients on HAART may be considered for implant-prosthetic rehabilitation. Keywords: dental implants, HIV-positive patients, highly active antiretroviral therapy, immunocompromised patients, implant-supported prosthetic rehabilitation