The International Journal of Oral & Maxillofacial Implants, 01/2007

Purpose: A split-mouth study was conducted to compare dental implants with either machined or titanium oxide (TiO) surfaces immediately loaded with fixed partial dentures in the posterior mandible. Materials and Methods: Ten patients with bilateral partial edentulism in the posterior mandible received 42 implants; 20 on the test (TiO) and 22 on the control (machined) side. The implants were loaded within 24 hours postsurgery. At implant placement the maximum insertion torque (IT) was recorded. Implant stability quotient (ISQ) was also evaluated at baseline (day 0) and 1, 2, 4, 12, 24, and 52 weeks following implant placement. The radiographic bone level (RBL) change was measured on periapical radiographs at baseline and 12 months after loading. Means for the 2 groups were compared by paired t test. Results: The overall implant success rate was 95%. No implants were lost in the test group; 2 failed in the control group. The difference between the groups in RBL change after 1 year of function was not statistically significant (P = .224). However, average RBL change for machined implants in distal positions was significantly higher than for TiO surface implants in the same position (post-hoc comparison; P = .048). ISQ and peak IT values did not differ between the groups (P = .414 and P = .762, respectively). The high IT necessary to insert the implants did not seem to affect the RBL change (P = .203). Conclusions: No significant difference was observed between machined and TiO implant surface in terms of RBL change or ISQ, although TiO implants may provide a lower RBL change compared to machined implants when utilized in the distal position. Immediate loading of implants using fixed partial dentures in posterior mandible may be considered as a treatment option if implants are inserted with IT ¡Ý 20 Ncm and ISQ ¡Ý 60 into nonaugmented bone and loaded with light centric occlusal contact. (More than 50 references) Keywords: dental implants, immediate loading, randomized controlled trials

Purpose: This retrospective study was designed to evaluate the volume of hard tissue generated at the time of implant placement in distracted alveolar bone. Materials and Methods: All patients who underwent distraction osteogenesis between 2000 and 2003 were included. The preoperative bone height, amount of distraction performed, and presence or absence of complications affecting implant placement were recorded. The augmentation achieved was correlated with insufficient bone formation using the Spearman correlation and the Fisher exact test. Results: The study included 43 implants placed in 17 cases of alveolar distraction. Of the 34 implants placed in bone augmented by 4.5 to 6.5 mm, bone defects were observed with 12. All 9 implants placed in ridges augmented by 7 to 10.5 mm demonstrated a bone defect. The ¡°defect¡± and ¡°no-defect¡± implant groups differed significantly with respect to preoperative bone height and amount of distraction performed (P .001 for both). Significantly more defects were formed in bone augmented by > 25% compared to bone augmented by ¡Ü 25% (P .001). Conclusions: When considering distraction osteogenesis, augmentation of up to 25% of the initial bone height seems more predictable and less likely to be associated with complications at the time of implant placement. In distractions greater than 25% of the original height, additional treatment should be considered. Keywords: alveolar distraction, bone regeneration, dental implants, distraction

Purpose: Nitrite is a stable end-product of nitric oxide oxidation. The aim of the present study was to quantitatively analyze peri-implant sulcular fluid (PISF) nitrite levels in a longitudinal study design to evaluate the potential changes in nitric oxide metabolism in relation to the clinical status of the peri-implant site and the loading style of the dental implants. Materials and Methods: A total of 34 implants, either early loaded (EL) or delayed loaded (DL), in 17 patients were followed up for a period of 18 months. Clinical parameters were recorded, PISF samples were obtained, and PISF nitrite levels were spectrophotometrically determined. Clinical measurements and nitrite analysis were repeated at 1, 3, 6, 9, 12, and 18 months. Results: Despite the gradual decrease in clinical parameters, fluctuations in PISF total nitrite levels were observed during follow-up. The pattern of nitric oxide metabolism, as reflected by PISF nitrite levels, also demonstrated differences between EL and DL implants that diminished toward the end of the experimental period. Discussion: Although the presence of clinical and subclinical gingival inflammation contributes to the PISF total nitrite levels, nitric oxide metabolism is also associated with healing and bone remodeling, and the pattern of loading seemed to have an impact on nitric oxide production at dental implant sites. Conclusion: Nitric oxide production at dental implant sites seems to be tightly regulated to enable the maintenance of peri-implant bone. Keywords: comparative studies, dental implants, loading, longitudinal study, nitric oxide, nitrite

Purpose: The aim of this study was to evaluate the influence of bone condensation and crestal preparation on the bone response of implants designed to promote osseocompression. Materials and Methods: In the first phase, the mandibular premolars of 6 dogs were extracted bilaterally. After 8 weeks, each dog received 8 Xive implants (4 per hemimandible). One hemimandible was randomly assigned to the experimental group and the other to the control group. The implant site was prepared using conventional standard drills. Prior to implant placement the crestal drill was used in the experimental group but not in the control group. After 12 weeks, the animals were sedated and sacrificed. The hemimandibles were removed and prepared for histomorphometric analysis of bone-implant contact (BIC) and bone density of areas adjacent to and further from the implant surface. Results: The mean ± SD percentages of BIC attained were 71.1% ± 11.8% and 45.1% ± 16.1% for the experimental and control groups, respectively. The bone density analysis revealed that in the control group, percentage BIC was a mean of 55.6% ± 11.3% adjacent to the implant and 50.7% ± 17.9% distant from the implant. In the experimental group, percentage BIC was a mean of 71.1% ± 8.6% adjacent to the implant and 55.6 ± 11.3 distant from the implant. The difference between the experimental and control groups was statistically significant for both parameters, BIC and bone density, in the adjacent areas (P .0001). Conclusion: Crestal preparation is of fundamental importance for this implant system, since it led to better bone response, represented by the improved BIC and bone density. Keywords: bone condensation, bone density, bone-to-implant contact, clinical protocols, dental implants

Purpose: The purpose of this study was to evaluate in vitro the accuracy of 2 methods for computerized tomography (CT) -guided template production via a surgical navigation system. Materials and Methods: Oral implants were planned on CT scans of standard dental stone casts with integrated target pellets. Method 1 used the aiming device of the navigation system for direct positioning of 2-mm surgical bur tubes on the dental stone casts. In method 2, the aiming device was used to guide drillings into the dental stone casts, and the surgical bur tubes were indirectly positioned by metal rods inserted in the drill holes. In both methods the bur tubes were affixed in a resin template. The accuracy of the obtained templates was evaluated by postoperative CT scans using descriptive statistics and the Student t test (P .05 considered significant). Results: The mean accuracy (normal deviation from the defined targets) of method 1 was 0.5 ± 0.3 mm (max 1.2 mm; n = 56). Mean accuracy for method 2 was 0.6 ± 0.3 mm (max 1.4 mm; n = 56). No significant difference was found between the maxillary and mandibular templates. Discussion: Conventional navigation systems already installed in many hospitals may be used for surgical template production. In contrast to intraoperative tool tracking, there is no need for patient tracking, and the planned implant axis can be rigidly secured as precisely as technically feasible with the help of an aiming device. Conclusion: Both methods of bur tube positioning may represent a precise means for CT-guided template production. Keywords: accuracy, image-guided template production, oral implant surgery, surgical navigation

Purpose: Recently, histologic studies in the beagle dog model demonstrated that CO2 laser-assisted implant decontamination can result in reosseointegration. Consequently, the purpose of this study was to assess the efficacy of CO2 laser-assisted therapy as compared with conventional therapy, with the concomitant use of b-tricalcium phosphate, in humans. Materials and Methods: The study included 32 patients with 73 ailing implants. In the laser group, 22 implants were treated with soft tissue resection following laser decontamination; whereas in 17 implants, bone augmentation was performed. In the control group, soft tissue resection after conventional decontamination was performed in 19 implants, augmentation in 15 implants. Results were evaluated 4 months after surgery and in May 2004. Results: Four months after therapy, there were no significant differences in distance from implant shoulder to the first bone contact (ie, DIB values) between implants undergoing laser decontamination and soft tissue resection and implants treated with conventional decontamination followed by soft tissue resection. At the end of the study, there was a statistically significant difference between these 2 groups. Four months after therapy, DIB values after laser decontamination and augmentation were significantly more favorable than after conventional decontamination and augmentation. This difference was no longer detectable at the end of the study. Conclusion: Based on the results of this study, it may be concluded that the treatment of peri-implantitis may be accelerated by using a CO2 laser concomitant with soft tissue resection. However, with respect to long-term results in augmented defects, there seems to be no difference between laser and conventional decontamination. Keywords: CO2 laser, guided bone regeneration, peri-implantitis

Purpose: To evaluate success rates and complications of implants placed with a flapless technique and immediately loaded in fully edentulous maxillae. Materials and Methods: Implants were placed in fully edentulous maxillae with a minimum insertion torque of 45 Ncm in underprepared sites to allow maximum stability at insertion using a flapless technique. Implants were immediately loaded. Outcome measures were prosthesis and implant success, biologic and prosthetic complications, pain, and edema evaluation. Stability of individual implants was assessed both manually and with Osstell at baseline and after 12 months of loading. A single sample t test was used with a significance level of .05. Results: Thirty-three consecutively treated edentulous patients received 202 implants in the maxilla. In 10 patients, 53 implants were immediately inserted in fresh extraction sockets. At implant insertion, a flap had to be elevated to control the direction of the drill in 5 patients. Three implants in 2 patients did not reach sufficient stability and were left to heal for 45 to 90 days. All restorations (21 fixed prostheses and 12 overdentures) were delivered the same day of the surgery. Twenty-six patients experienced no or slight postoperative pain; 7 experienced moderate to severe pain. No or slight edema was recorded for 19 patients and moderate to severe edema for 14 patients. Two implants failed in 2 patients but were successfully replaced the same day they were removed. No major complications occurred. Five patients experienced biologic complications, eg, peri-implantitis; 10 experienced prosthetic complications. No prosthesis failed; however, 1 patient was unsatisfied with his overdenture and requested a fixed alternative. There was a highly significant difference (P .001) between the stability at implant insertion and after 12 months. Conclusion: Implants placed in the edentulous maxilla with a flapless procedure can be successfully loaded the same day of surgery. Keywords: dental implants, edentulous maxilla, flapless procedures, immediate loading

Purpose: To compare the ability of 2 radiographic methods, intraoral and panoramic radiography, commonly used in private practices following implant treatment to provide reliable information about the level of peri-implant marginal bone. An additional aim was to compare the inter- and intraobserver reliability. Materials and Methods: Patients with implants placed in the mandible in 10 private practices were studied retrospectively. Postoperative intraoral and panoramic radiographs were evaluated at a university oral radiology clinic. Two observers, a specialist in oral and maxillofacial radiology and a specialist in oral and maxillofacial surgery, assessed the bone level, and the thread at which the marginal bone seemed to be attached was registered for the distal and mesial surfaces of all implants at 2 assessments several weeks apart. Kappa statistics was used to compare the agreement between assessments, observers, and methods of radiography. Results: Intraobserver agreement was good or very good, while interobserver agreement was predominantly moderate. The agreement rate between the methods was also moderate. Seven percent of the sites were not possible to assess, with a small difference in favor for panoramic radiographs. In the assessment of the panoramic radiographs, the radiologist found more sites too difficult to assess than the surgeon did. Conclusions: In this study, panoramic radiographs were found to be as reliable as conventional intraoral radiographs when used to assess the point of bone attachment to implant threads. Intra- and interobserver agreement were reliable but not excellent. The radiologist was more successful in finding sites where the bone level was impossible to assess accurately. Keywords: bone height assessment, dental implants, intraoral radiographs, observer agreement, panoramic radiographs

Purpose: To compare the biomechanical effect of splinted versus unsplinted mandibular implants supporting overdentures subjected to experimental static immediate load on bone tissue deformation using strain gauge analysis. Materials and Methods: Strain gauges were bonded on the labial cortical bone adjacent to 2 Straumann dental implants placed in the mandibular interforaminal region of 4 completely edentulous mandibles of fresh human cadavers. The installation torque value (ITV) of each implant was measured using a custom-made torque wrench, and implant stability quotients (ISQs) were also obtained using resonance frequency analysis. Three overdentures (ODs), 2 splinted (bar- and cantilevered bar-retained) and 1 unsplinted (ball-retained), were fabricated for each edentulous mandible. Two experimental loads were applied subsequently via 2 miniature load cells that were placed bilaterally 10 mm (anterior loading) and 15 mm (posterior loading) from the implant. Strain measurements were performed at a sample rate of 10 KHz and under a maximum experimental static load of 100 N; they were simultaneously monitored from a computer connected to a data acquisition system. Finally, the removal torque values (RTV) of the implants were measured. Results: Strains on the labial cortical bone around implants supporting mandibular ODs under anterior loading were significantly higher than measured under posterior loading for all attachment types (P .05). All strain values were compressive in nature, and the minimum strain (-19 µe) was recorded for bar-retained ODs under 25 N posterior loading, while the maximum strain (-797 µe) was for recorded for retentive anchor-retained ODs under 100 N anterior loading. Nonparametric correlations between ISQs, ITVs, and RTVs identified significant correlations only for ITVs and RTVs (P .05). Conclusion: Splinting of 2 interforaminal dental implants, regardless of attachment type, to support mandibular ODs subjected to immediate load significantly reduced initial bone tissue strains experienced on the labial cortical bone in comparison with the use of unsplinted implants. Keywords: biomechanics, dental implants, immediate loading, mandibular overdentures, micromovement, resonance frequency analysis, strain gauges

Purpose: To estimate the survival rate of implants placed with the osteotome technique by means of a systematic review. Materials and Methods: The literature was searched using Medline; the search was limited to the years 1953 to 2005. Inclusion criteria were: (1) clinical studies or clinical reports investigating the osteotome technique for dental implantation and (2) control or test group(s) from clinical studies or clinical reports, even if they did not fit with other criteria. By pooling the data of the included studies, overall Kaplan-Meier survival curves were constructed for the periods before and after loading. Results: The initial literature search yielded 164 studies. After selection criteria were applied, 5 studies were considered suitable for inclusion. The combined data of 349 implants revealed survival probabilities of 98% (confidence interval [CI], 97.2% to 100%) until loading and 99% (CI, 94% to 100%) after 56 months of loading. At the end of the observation period 41 implants in 18 patients were still at risk. Conclusion: The outcome of dental implantation using the osteotome technique in terms of implant survival seems to be similar to that of implants placed by means of the conventional implantation technique. Keywords: dental implants, meta-analysis systematic review, osteotome technique

Purpose: Prevention of late implant bone loss is a critical component in long-term success of implants. The aim of the present study was to evaluate factors affecting late implant bone loss. Materials and Methods: Three hundred thirty-nine endosseous root-form dental implants placed between April 1981 and April 2002 in 69 patients were analyzed. The implants were categorized based on the following factors: (1) surface characteristics (smooth versus rough), (2) length (short [ 10 mm] versus long [¡Ý 10 mm]), width (narrow [ 3.75 mm], regular [3.75 to 4.0 mm], or wide [> 4.0 mm]), (3) the amount of keratinized mucosa ( or ¡Ý 2 mm), (4) location (anterior versus posterior; maxilla versus mandible), (5) type of prosthesis (fixed versus removable), and (6) type of opposing dentition. The effects of these factors on clinical parameters, especially average annual bone loss (ABL), were evaluated clinically and radiographically by a blinded examiner. The parameters evaluated were modified Plaque Index, Gingival Index, modified Bleeding Index, probing depth, and ABL. Results: Shorter implants, wider implants, implants supporting fixed prostheses, and implants in smokers were found to be associated with greater ABL (P .05). The random intercept mixed effects model showed that implant length was the most critical factor for maintenance of ABL. Conclusions: Shorter implants, wider implants, implants supporting fixed prostheses, and implants in smokers were associated with greater ABL. Implant length was the most significant factor in the maintenance of dental implants. Randomized controlled clinical trials are needed to confirm the results obtained from this retrospective clinical study. (Case Series) (More than 50 references.) Keywords: implant maintenance, implant surfaces, late implant bone loss, peri-implantitis

Purpose: To describe the anatomy of the lingual perimandibular vessels and emphasize the distance to the bone. Materials and Methods: The hemifacial lower third was dissected in 12 human cadavers. The blood vessels in the floor of the mouth were exposed using sagittal incisions at the canine, mental foramen, and second molar areas. Results: The diameter of the dissected vessels ranged from 0.5 to 3 mm (mean, 1.5 mm). Most vessels were found superior to the mylohyoid muscle in the canine area and beneath the muscle in the mental and second molar areas. The smallest median vertical distance from blood vessel to bone was in the canine area (14.5 mm), followed by the mental foramen area (15.5 mm) and the second premolar area (19 mm). The median horizontal distance of the vessels from the lingual plate was 2 mm at the canine and second molar areas and 4 mm at the mental area. Discussion: Lingual plate perforation, especially anterior to the canine area, can easily injure blood vessels in the floor of the mouth and cause life-threatening hemorrhage following implant placement. Bleeding can occur when the mandibular lingual plate is perforated. Care should be taken to recognize situations where this complication may occur. Conclusions: Based on the study of human cadavers, it appears that vessels in the floor of the mouth are sometimes in close proximity to the site of implant placement. Caution should be exercised when placing implants in this area. (Basic Science) Keywords: dental implants, lingual perimandibular vessels, sublingual artery, submental artery

Purpose: The purpose of this study is to report on the use of a computer-assisted design (CAD) system for predictable preoperative planning of orbital implant surgery (determination of the optimal number and position of orbital implants). Materials and Methods: Preoperative computed tomographic data were processed by interactive software for predictable surgical planning of orbital implant placement. Reformatted images from axial scans were used to analyze the structure of orbital bone and to plan the number of implants to place and the sites in which to place them. Results: Surgeries to correct orbital defects in 6 patients were successfully designed with this method. Seventeen implants were placed in 6 patients with the CAD system with no intraoperative injuries. Satisfactory anatomic and esthetic results were achieved. Conclusions: The new CAD system optimized preoperative surgical planning for orbital implant placement. The software may be applied in other craniofacial areas for implant placement in the future. (Case Series) Keywords: computer-assisted design, craniofacial implants, orbital defects, templates, 3-dimensional reconstruction

Purpose: To describe a new drilling system that allows the surgeon to obtain autologous living bone that, when associated with a plasma rich in growth factors (PRGF), can be used in bone grafting. Materials and Methods: Bone particles collected using both conventional and new drilling systems were analyzed by means of optic and electronic microscopy in 10 patients. Blood was collected from 43 volunteers and used to prepare PRGF. Quantitative aspects of the PRGF, including number of platelets and concentration of growth factors (insulin growth factor [IGF-I], transforming growth factor [TGF-b1], platelet-derived growth factor [PDGF-AB], vascular endothelial growth factor [VEGF], hepatocyte growth factor [HGF], and epidermal growth factor [EGF]) were assessed. A demonstrative case study was presented. Results: Microscopic examination showed that the bone structure and the presence of living cells in the bone chips were conserved in all samples obtained from drilling at low speed, whereas material obtained by conventional drilling did not maintain these qualities. Mean counts for TGF-b1 (55.27 ± 16.23 ng/mL), PDGF-AB (27.96 ± 12.13 ng/mL), VEGF (421.09 ± 399.0 pg/mL), EGF (455.49 ± 210.04 pg/mL), and HGF (605.70 ± 269.20 pg/mL) were significantly correlated with the number of platelets (590,000 ± 197,000 platelets/µL; P .05). Discussion and Conclusion: The new drilling procedure was developed based on biologic criteria. The method may reduce damage to the host tissue and can be used to obtain a mass of living bone for subsequent grafting in association with autologous growth factors. This new procedure may present new possibilities for enhanced bone healing and needs to be evaluated in a clinical trial. (Technical Note) Keywords: autografts, dental implants, low-speed drills, preparation rich in growth

The development of osteonecrotic lesions of the jaws has been described as being associated with the use of bisphosphonates. Although most clinical reports described the association between necrotic lesions and the use of this group of medications for the management of osseous lesions associated with malignancies such as multiple myeloma, metastatic breast cancer, or prostate cancer, there are reports of osteonecrosis in the jaws of patients who are using oral bisphosphonates to treat osteoporosis. Given the number of patients taking this medication for the management of osteoporosis, it is obvious that the risks and benefits of the medication need to be clearly defined. Could you comment on the risks of oral bisphosphonate use toward the development of osteonecrotic lesions of the jaws? In addition, could you postulate on studies that may better define this risk?