Fiber-reinforced composite full-arch prosthetic reconstructions supported by three standard, short or extra-short implants: a two-center retrospective study.

OBJECTIVES: To evaluate the survival of implants and prostheses, and marginal bone level of fiber-reinforced composite implant supported fixed complete prostheses supported by 3 implants. MATERIALS AND METHODS: Patients with fiber-reinforced composite fixed prostheses supported by 3 standard-length, short or extra-short implants were included in this retrospective cohort study. Kaplan-Meier survival was computed for implants and prostheses. Univariate and multivariate Cox proportional hazard regressions, clustered by patient, were used to analyze bone level differences as a function of different study covariates. Linear regressions were used to investigate the relationship between distal extension lengths and bone levels. RESULTS: Forty-five patients with 138 implants were followed for up to 10 years after prosthesis insertion (mean 52.8; SD 20.5 months). Kaplan-Meier survival analysis showed overall survival rates of 96.5% for implants and of 97.8% for prostheses. The 10-year success rate for prostheses was 90.8%. Extra-short implants survived at similar rates to short and standard implants. Marginal bone levels surrounding implants remained stable over time, even showing slight bone gain on average (mean + 0.1 mm/year; SD ± 0.5 mm/year) Acrylic denture teeth, overdentures on the opposing arch, and implant placement in the posterior maxilla were correlated with bone gain. Screw retention, opposed to telescopic retention, was correlated with bone loss. Longer distal extensions were correlated with bone gain on the implants closest to the distal extensions. CONCLUSIONS: Fiber-reinforced composite fixed prostheses supported by only 3 implants, most of which were extra-short, presented high survival rates with stable bone levels. CLINICAL RELEVANCE: An encouraging prognosis can be expected for restoration of atrophic maxillary and mandibular arches, when restored with fixed fiber-reinforced composite frameworks with long distal extensions and supported on only 3 short implants.

Severely Atrophic Mandibles Restored With Fiber-Reinforced Composite Prostheses Supported by 5.0-mm Ultra-Short Implants Present High Survival Rates Up To Eight Years.

PURPOSE: Encouraging results have been reported for ultrashort single implants; however, long-term investigations are warranted for full-arch reconstructions. This study evaluated marginal bone loss, implant, and reconstruction survival of fiber-reinforced composite full-arch prostheses supported by 4 ultrashort implants. METHODS: Patients with severely atrophic mandibles (Cawood and Howell class V and class VI) were included in this cohort study. Study predictors included time (initial and last follow-up) and vertical (epicrestally or subcrestally) and horizontal implant position (medial or lateral). Outcome variables included bone level changes over time, implant/prosthesis survival. Peri-implant bone level was measured on panoramic radiographs. Descriptive statistics, Kaplan-Meier, mixed model analysis of variance, and univariate and multivariate Cox Proportional Hazards Regression models, adjusted for multiple implants in the same patient, were used for data analyses. RESULTS: Eighteen patients (mean 61.22 years old), with 72 implants placed in atrophic mandibles with an average follow-up of 55.4 months (CI, ±4.6/ SD, ±10.6 months) were analyzed. The implant survival rate was 97.2% as 2 implants were not loaded due to non-osseointegration and sensorial disturbances. Average marginal bone level at baseline (1.93 mm) and at the time of last recall (1.91 mm) was not significantly different. While implants placed subcrestally showed no significant difference between baseline (1.91 mm) and last follow up bone level (2.12 mm), implants placed epicrestally demonstrated a significant reduction on their bone level over time (initial: 1.97 mm/ final:1.33 mm). Systemic disorders were a risk factor for implant survival and bone loss. Prostheses cumulative survival rate was 100% (mean observation period of 55 months). The estimated survival rate after the 96-month follow-up was 75% (1 framework fracture after 84 months). CONCLUSION: Fixed fiber-reinforced composite full-arch prostheses retained by 4 ultrashort implants showed a stable bone level and high implant/prostheses survival rates up to 8 years.

Antiresorptive therapy and dental implant survival: an up to 20-year retrospective cohort study in women.

OBJECTIVES: To investigate the effects of antiresorptive treatment on the survival of plateau-root form dental implants. MATERIALS AND METHODS: Patients undergoing antiresorptive therapy via oral or intravenous administration as well as patients not undergoing antiresorptive therapy and healthy control patients were included in this retrospective cohort study. In total, 1472 implants placed in 631 postmenopausal patients (M: 66.42 ± 9.10 years old), who were followed for a period of up to 20 years (8.78 ± 5.68 years). Kaplan-Meier survival analysis was performed, and univariate and multivariate Cox regression, clustered by each patient, was used to evaluate and study factors affecting the survival of their implants. RESULTS: Implants placed in patients undergoing oral antiresorptive treatment presented significantly higher survival rates, than implants placed in the osteoporosis/osteopenia control cohort (p value < 0.001), and similar survival rates, when compared to healthy controls (p value = 0.03). Additionally, clustered univariate and multivariate Cox regression analysis also revealed higher implant survival when oral antiresorptive drugs (p value = 0.01 and 0.007, respectively) were used, and lower implant survival in the presence of untreated osteoporosis/osteopenia (p value = 0.002 and 0.005, respectively). Overall, the 20-year implant survival in osteoporotic patients undergoing antiresorptive therapy was 94%. For the failed implants, newly replaced implants in patients under antiresorptive treatment presented a 10-year survival of 89%. CONCLUSIONS: Long-term plateau-root form implant survival in osteoporotic patients taking oral antiresorptives was similar to a healthy population and significantly higher than the untreated controls. CLINICAL RELEVANCE: These results suggest that plateau-root form implants provide a robust solution for treating tooth loss in patients, who are undergoing antiresorptive therapy.

Fiber-Reinforced Resin Fixed Prostheses on 4 Short Implants in Severely Atrophic Maxillas: 1-Year Results of a Prospective Cohort Study.

PURPOSE: The aim of this study was to report on 1-year outcomes of fixed full-arch fiber-reinforced resin bridges on short implants in atrophic maxillary jaws. MATERIALS AND METHODS: A prospective cohort study was designed and patients with severely atrophic maxillas, corresponding to Cawood and Howell Classes V and VI, were included. Mesial and distal peri-implant bone levels were assessed on panoramic radiographs that were taken at the time of implant insertion (baseline) and during follow-up visits. RESULTS: Eighteen patients with 72 implants inserted in atrophic maxillary jaws were included in this study. All patients had a follow-up visit 1 year after loading. The cumulative 1-year patient-based implant survival rate was 88.8%, and the cumulative 1-year implant-based survival rate was 97.2%. The marginal bone level (MBL) was -0.5 ± 0.5 mm at the time of loading (n = 72) and -0.8 ± 0.6 mm (n = 72) after 1 year. The MBL depended substantially on the depth at the time of insertion. No prosthetic failure, such as chipping or fracture, occurred within the first year of loading. CONCLUSION: Prosthetic rehabilitation of atrophic maxillas with prostheses supported by 4 4.0- × 5.0-mm or 3.0- × 8.0-mm implants seems to be a viable and cost-effective treatment option in the short-term.

Fixed, Fiber-Reinforced Resin Bridges on 5.0-mm Implants in Severely Atrophic Mandibles: Up to 5 Years' Follow-Up of a Prospective Cohort Study.

PURPOSE: The aim of this study was to evaluate the midterm outcomes of fixed, full-arch, fiber-reinforced resin bridges on ultrashort implants in terms of marginal bone loss and overall implant survival. PATIENTS AND METHODS: Patients with severely atrophic mandibles, corresponding to Cawood and Howell class V and class VI, were included in this prospective temporal cohort study. Mesial and distal peri-implant bone levels were measured on panoramic radiographs taken at the time of implant insertion (baseline) and at follow-up visits. RESULTS: A total of 17 patients with atrophic mandibular jaws with an average follow-up period of 2.9 ± 1.5 years were included. The cumulative 1-, 3-, and 5-year patient-based implant survival rates were 94.1%, and the cumulative implant survival rates were 98.5%. The marginal bone level (MBL) of the mesial implants was 0.0 ± 0.3 mm at the time of loading (n = 33), -0.1 ± 0.3 mm (n = 20) after 1 year, -0.4 ± 0.5 mm (n = 10) after 3 years, and -1.5 ± 1.0 mm (n = 4) after 5 years. The mesial bone level depended significantly on time and insertion depth. The MBL of the distal implants was -0.4 ± 0.4 mm (n = 34) at the time of implantation, -0.4 ± 0.6 mm (n = 20) after 1 year, -0.5 ± 0.5 mm (n = 10) after 3 years, and -2.2 ± 1.7 mm (n = 4) after 5 years. The distal bone level depended significantly on time and insertion depth. CONCLUSIONS: Fixed, full-arch, fiber-reinforced resin bridges retained by 4 ultrashort implants provide a comparatively cost-effective, safe, stable alternative for prosthetic restoration of the severely atrophic mandible. The overall implant survival rate and the MBL after 5 years are equivalent to those of threaded implants of conventional lengths.

Preliminary results of fixed, fiber-reinforced resin bridges on four 4- × 5-mm ultrashort implants in compromised bony sites: a pilot study.

PURPOSE: To determine the effectiveness of fixed, fiber-reinforced resin bridges on 4 ultrashort implants with a sufficient implant survival success rate of at least 90% in highly atrophic jaws. MATERIALS AND METHODS: A prospective temporal cohort study was designed, with the inclusion of 10 patients. Of the 10 patients, 8 had atrophic jaws (7 women, 1 man; mean age at implant placement 58.5 years, range 40.7 to 73.9) and 2 had fibula-mandibular transplants (1 woman, aged 76.5 years; and 1 man, aged 69.3 years). All 10 patients had their dentition restored with 4 ultrashort implants. The implant dimensions were 4 mm in diameter and 5 mm long, with a locking taper abutment connection supporting a fixed, fiber-reinforced and composite resin-facetted bridge. The postoperative follow-up period averaged 19.5 months (range 9.1 to 33.1). RESULTS: The survival and success rate was 97.25%. The average mesial and distal bone level was 0.2 ± 0.3 mm in the atrophic mandibles and 0.4 ± 1.2 mm in the fibula transplants at the last follow-up visit. Prosthetic-related patient issues were limited to decementation events. No chipping or fracturing of the prostheses was observed. CONCLUSION: Retention of fixed prosthetic restorations using 4 ultrashort implants showed promising short-term cumulative survival and success rates.

Effect of dental implants on bisphosphonate-related osteonecrosis of the jaws.

PURPOSE: Bisphosphonate (BP)-related osteonecrosis of the jaw (BRONJ) is a side effect of BP therapy. Dental implants are believed to be a risk factor for developing BRONJ. In the present study, we analyzed the interval to the development of BRONJ in patients treated with BP who had received dental implants. PATIENTS AND METHODS: Patients with dental implants and established BRONJ were evaluated at the oral and maxillofacial surgery department (Medical University of Vienna). In addition, studies from 1978 to 2012 were included in a meta-analysis. Three groups were created: implantation before BP treatment, implantation after BP treatment, and implantation during BP treatment. The outcomes were evaluated using linear regression analysis. RESULTS: Patients who underwent dental implantation during (P < .001) and after (P < .001) treatment with BPs developed BRONJ more rapidly. The treatment duration with oral BPs was significantly related to the rapidity of developing BRONJ (P = .03). CONCLUSIONS: The insertion of dental implants during or after BP treatment accelerated the development of BRONJ. BRONJ occurred less frequently when the implants had been inserted before BP therapy had been started.

Patient-specific polyetheretherketone facial implants in a computer-aided planning workflow.

PURPOSE: In the present study, we report an innovative workflow using polyetheretherketone (PEEK) patient-specific implants for esthetic corrections in the facial region through onlay grafting. The planning includes implant design according to virtual osteotomy and generation of a subtraction volume. The implant design was refined by stepwise changing the implant geometry according to soft tissue simulations. MATERIALS AND METHODS: One patient was scanned using computed tomography. PEEK implants were interactively designed and manufactured using rapid prototyping techniques. Positioning intraoperatively was assisted by computer-aided navigation. Two months after surgery, a 3-dimensional surface model of the patient's face was generated using photogrammetry. Finally, the Hausdorff distance calculation was used to quantify the overall error, encompassing the failures in soft tissue simulation and implantation. RESULTS: The implant positioning process during surgery was satisfactory. The simulated soft tissue surface and the photogrammetry scan of the patient showed a high correspondence, especially where the skin covered the implants. The mean total error (Hausdorff distance) was 0.81 ± 1.00 mm (median 0.48, interquartile range 1.11). The spatial deviation remained less than 0.7 mm for the vast majority of points. CONCLUSIONS: The proposed workflow provides a complete computer-aided design, computer-aided manufacturing, and computer-aided surgery chain for implant design, allowing for soft tissue simulation, fabrication of patient-specific implants, and image-guided surgery to position the implants. Much of the surgical complexity resulting from osteotomies of the zygoma, chin, or mandibular angle might be transferred into the planning phase of patient-specific implants.

Partial fixed dental prostheses fabricated using fiber-reinforced composite resin supported by short and extra-short implants: A case series.

PURPOSE: This study aimed to evaluate the 10-year outcomes of partial fixed dental prostheses (P-FDPs) fabricated using metal-free fiber-reinforced composite (FRC) resin frameworks veneered with composite resin and supported by short and extra-short implants. METHODS: This study included 28 patients with 38 FRC prostheses supported by 96 implants. Implant and prosthesis survival and success rates were evaluated using Kaplan-Meier analysis. RESULTS: The 10-year implant survival and success rate, as determined by Kaplan-Meier analysis, was 96.9%, and the prosthesis survival and success rates were 94.7% and 92.0%, respectively. None of the parameters under investigation were significantly correlated with prosthetic survival or successful outcomes, but three parameters were correlated with higher peri-implant bone levels: implant placement in the mandible as opposed to the maxilla, shorter P-FDP spans, and natural teeth on the opposing arch. CONCLUSIONS: FRC P-FDPs supported by short and extra-short implants presented high, up to 10-year, survival and success rates, when used to restore partially edentulous arches.

Short dental implants in microvascular free flap DCIA: A case report.

Placing dental implants in microvascular bone free flaps used for reconstructing the mandible or maxilla has been previously reported. However, there is scarce information available on the restorative protocol using short dental implants placed in a deep circumflex iliac artery (DCIA) microvascular free flap and the rationale behind it. This case report describes a 18-year-old patient referred to the hospital for numbness and dull pain of the left mandible, which she observed for three months. The patient underwent mandible resection and reconstruction using the DCIA free flap due to "giant cell lesion" on the left side of the mandibular angle. Short dental implants were placed and prosthetic reconstruction of the dentition involved in the resection was performed in a young patient with two integrated abutment crowns. The placement of short dental implants did not negatively affect the vascular pedicle and vitality of free flap. In our case report, two years after the healing, excellent aesthetic and function were accomplished with the DCIA flap followed by restoration with short implants.

Short and Extra Short Dental Implants in Osseous Microvascular Free Flaps: A Retrospective Case Series.

There is limited information regarding implant and prosthetic survival after osseous microvascular free flap (OMFF). This case series aims to describe the placement of short and extra short implants in osseous microvascular free flaps to support prostheses, and present an up to 40-month retrospective follow-up. Short and extra short dental implants were placed in six fibula free flaps (FFF) and in two microvascular deep circumflex iliac artery (DCIA) flaps. In total, 27 short and extra short dental implants have been placed into two different types of free flaps. Kaplan-Meyer (K-M) survival analyses were performed to evaluate the survival and success outcomes of implants and prostheses. Out of the eight patients reconstructed with free flap, five were rehabilitated with prostheses, one patient has a temporary prosthesis, and two patients are in the process of prosthetic rehabilitation. Twenty-seven implants were followed up for up to 40 months, and K-M analyses showed 100% implant survival probability (95% confidence interval: 100%), while the implant success probability was 91.0% (95% confidence interval: 68.6-97.7%). Short and extra short dental implants placed in OMFF presented high survival and success rates in a retrospective case series after up to 40 months.

Palatal sinus elevation revisited: a technical note.

The palatal sinus lift is a good choice for patients with scarred buccal soft tissue and those with poor wound healing such as smokers or diabetics or when visual side effects such as swelling must be concealed. We provide a surgical protocol for palatal sinus lifting without a vertical release incision. The incision is started in a slightly palatal aspect, at the distal end of the dental arch, and describes a curve laterally on the alveolar crest while running in a mesial direction. As a marginal incision, it can continue to the central incisor. Submucosal exposure will lift the gum and the greater palatine artery. After insertion of a tongue depressor, the sinus is opened on the palatal side, opposite the zygomaticoalveolar crest, using a rose bur or a piezotome. After sinus augmentation, the incision is easy to close, and the wound will heal smoothly.

Identifying risk factors for allogenic blood transfusion in oral and oropharyngeal cancer surgery with free flap reconstruction.

PURPOSE: Several observational studies in head and neck cancer have reported that allogenic blood transfusion is associated with increased postoperative complications, increased risk of tumor recurrence, and worse prognosis. The aim of this study was to identify preoperative and intraoperative factors predicting blood transfusion in patients undergoing surgery for oral and oropharyngeal cancer. PATIENTS AND METHODS: We conducted a retrospective cohort study of patients undergoing tumor resection and free flap reconstruction for locally advanced oral and oropharyngeal squamous cell carcinoma between 2000 and 2008. The primary outcome variable was perioperative exposure to allogenic blood transfusion. Univariate and multivariate logistic regression models were used to determine predictors of blood transfusion. RESULTS: A cohort of 142 participants was found eligible. In a multivariate model, Charlson score ≥ 1 (OR, 5.2; 95% CI, 1.4 to 19.3; P = .01), preoperative hemoglobin levels ≤ 12 g/dl (OR, 4.4; 95% CI, 1.2 to 16.2; P = .03), bone resection (OR, 5.1; 95% CI, 1.5 to 17.8; P = .01), and osseous free tissue transfer (OR, 8.8; 95% CI, 1.0 to 74.8; P = .046) were independently associated with an increased risk of blood transfusion. CONCLUSION: Our study identified patient- and surgery-related factors predicting a higher risk of exposure to allogenic blood transfusion. This readily available preoperative information could be used to better stratify patients according to their transfusion risk and may thereby guide blood conservation strategies in high-risk patients.

Comparison of cone-beam and conventional multislice computed tomography for image-guided dental implant planning.

OBJECTIVES: To compare the accuracy of cone-beam CT (CBCT) and multislice CT (MSCT) with regard to its use in image-guided dental implant surgery in a prospective model based study. MATERIAL AND METHODS: Ten photopolymer-acrylate mandibula models, each with four precise metal reference markers, were scanned with MSCT and CBCT. The six reference distances between the markers were measured by a three-axis milling machine first. The distances were then measured by (1) navigation with the Medtronic StealthStation® TREON™ image-guided surgery system, (2) with the Medtronic planning-tool and (3) on the PC with the Mimics® software. Mean values were calculated for all three methods for CBCT and MSCT and were compared for statistical significance. RESULTS: Of all measurements, 83% of the arithmetic mean values were within the ±0.5 mm range (MSCT 88% and CBCT 78%) and 17% within the ±1.0 mm range (MSCT 12% and CBCT 22%). The absolute difference of the arithmetic mean values showed no statistically significant difference between MSCT and CBCT. The difference of the overall mean values to the reference was 0.43 mm for MSCT and 0.46 mm for CBCT. CONCLUSIONS: The data of our study prove that the application of CBCT for the indicated purpose yielded good results comparable to those of MSCT. All three measuring methods were feasible and accuracy was statistically not different between the data acquired by MSCT and CBCT within the setting of this study.

Postoperative failure of platelet recovery is an independent risk factor for poor survival in patients with oral and oropharyngeal cancer.

OBJECTIVE: The aim of this study was to evaluate the postoperative platelet count changes in patients with oral and oropharyngeal squamous cell carcinoma undergoing preoperative chemoradiotherapy in order to test the hypothesis that the failure of platelets to recover to normal range within 7 days after surgery represents a significant risk factor for poor survival. MATERIALS AND METHODS: A cohort of 102 patients with primary locally advanced oral and oropharyngeal squamous cell carcinoma undergoing neoadjuvant chemoradiotherapy and surgery was retrospectively analyzed. For each patient, platelet counts were evaluated prior to neoadjuvant treatment, prior to surgery and throughout postoperative days 1 to 7. The Kaplan-Meier method and Cox regression models were used to assess the impact of platelet count changes on survival. RESULTS: Overall survival rate at 5 years was 28% for patients whose platelets did not recover by day 7, with 52% for patients whose platelets remained within a normal level or recovered to this by day 7 (p = 0.005). In multivariate analysis, failure of platelet recovery by day 7 was independently associated with shorter overall survival (p = 0.03). CONCLUSIONS: We demonstrated that the failure of platelets to recover to normal range by the seventh postoperative day is an independent adverse prognostic factor in patients with oral and oropharyngeal cancer undergoing neoadjuvant treatment and surgery. CLINICAL RELEVANCE: Our results indicate that physicians should pay closer attention to monitoring the postoperative platelet count course, as it may predict the clinical outcome of patients with oral and oropharyngeal cancer.

Immediate placement of extra-short implants in refined scapula tip microvascular free flaps: In house virtual planning and surgical technique - Proof of concept.

Scapula tip flaps have been introduced in the literature as an ideal surgical treatment option for large defects in the horizontal plane of the maxilla. This article aims to present a unique step by step protocol for a near total maxillectomy with a pterygoid bone resection and consecutive microvascular reconstruction with a harvested scapula tip flap. The protocol includes immediate placement of extra-short implants in donor bone with the aid of Virtual Surgical Planning (VSP), and an in-house 3D printing of medical 3D models and surgical guides. So far, there has been no presented surgical technique combining immediate implant placement in the scapula region with simultaneous microvascular repair. This technique allows: tumour resection; flap harvesting; extra-short implant placements and reconstruction to be performed in one simultaneous procedure. The technique is presented with illustrations, VSP (presented on videos), radiographs, and surgical findings. We discovered that this refinement of the scapula tip surgery has enabled reconstructive procedures to be performed at the same time as implant placements, providing expedited functional and aesthetic outcomes in selected cases. Moreover, modification of the surgical technique could enhance the competence of the oropharyngeal edge. In conclusion, this new surgical protocol utilizing VSP, 3D models and simultaneous extra-short implant placement provides indispensable advantages for such a complicated surgical procedures, while significantly shortening the duration of surgery.

Evaluation of immunohistochemical expression of p53, p21, p27, cyclin D1, and Ki67 in oral and oropharyngeal squamous cell carcinoma.

BACKGROUND: The purpose of this study was to evaluate whether the immunohistochemical expression of p53, p21, p27, cyclin D1, and Ki67 can predict therapy response and survival in patients with oral and oropharyngeal squamous cell carcinoma treated with preoperative chemoradiation. METHODS: Biomarker expression was evaluated by immunohistochemistry in formalin-fixed, paraffin-embedded pretreatment biopsies of 111 homogenously treated patients. We assessed the association between clinicopathological variables including response to neoadjuvant chemoradiotherapy as well as the survival of the patients and the expression of the biomarkers as both dichotomized (positive vs. negative) and continuous variables. RESULTS: Biomarker overexpression on the basis of pre-selected cutoff points was seen in 66 of 111 (59%) cases for p53, in 77 (69%) for p21, in 48 (43%) for p27, in 81 (73%) for cyclin D1, and in 54 (49%) cases for Ki67, respectively. None of the examined biomarkers was able to predict response to neoadjuvant chemoradiotherapy or was associated with survival outcome. Post-treatment pathologic TNM stage (P < 0.001), pathologic response (P < 0.001), and perineural invasion (P < 0.001) were the only factors having a significant effect on recurrence-free survival. Post-treatment pathologic N stage (P = 0.005), post-treatment pathologic TNM stage (P < 0.001), pathologic response (P < 0.001), and perineural invasion (P = 0.001) had a significant impact on overall survival. CONCLUSIONS: Our results suggest that the biomarkers p53, p21, p27, cyclin D1, and Ki67 have no impact on treatment response and survival in patients with oral and oropharyngeal cancer treated with preoperative chemoradiation.

Splint sterilization--a potential registration hazard in computer-assisted surgery.

PURPOSE: Registration of preoperative targeting information for the intraoperative situation is a crucial step in computer-assisted surgical interventions. Point-to-point registration using acrylic splints is among the most frequently used procedures. There are, however, no generally accepted recommendations for sterilization of the splint. An appropriate method for the thermolabile splint would be hydrogen peroxide-based plasma sterilization. This study evaluated the potential deformation of the splint undergoing such sterilization. Deformation was quantified using image-processing methods applied to computed tomographic (CT) volumes before and after sterilization. MATERIALS AND METHODS: An acrylic navigation splint was used as the study object. Eight metallic markers placed in the splint were used for registration. Six steel spheres in the mouthpiece were used as targets. Two CT volumes of the splint were acquired before and after 5 sterilization cycles using a hydrogen peroxide sterilizer. Point-to-point registration was applied, and fiducial and target registration errors were computed. Surfaces were extracted from CT scans and Hausdorff distances were derived. Effectiveness of sterilization was determined using Geobacillus stearothermophilus. RESULTS: Fiducial-based registration of CT scans before and after sterilization resulted in a mean fiducial registration error of 0.74 mm; the target registration error in the mouthpiece was 0.15 mm. The Hausdorff distance, describing the maximal deformation of the splint, was 2.51 mm. Ninety percent of point-surface distances were shorter than 0.61 mm, and 95% were shorter than 0.73 mm. No bacterial growth was found after the sterilization process. CONCLUSION: Hydrogen peroxide-based low-temperature plasma sterilization does not deform the splint, which is the base for correct computer-navigated surgery.

Application of platelet-rich plasma for enhanced bone regeneration in grafted sinus.

PURPOSE: The present study was conducted to evaluate the effect of platelet-rich plasma (PRP) on new bone formation and remodeling after grafting of the maxillary sinus with an algae-derived hydroxyapatite AlgOss/C Graft/Algipore. MATERIALS AND METHODS: Fourteen consecutive patients with severely atrophic maxillae underwent uni- or bilateral grafting of the maxillary sinus with a mixture of collected bone, algae-derived hydroxyapatite AlgOss/C Graft/Algipore (ratio 1:10), and a combined addition of PRP and thrombin (Tissucol Kit; Baxter, Vienna, Austria) to allow for fast clotting. After an average healing period of 7.1 months bone samples were retrieved. Patients from a former consecutive series treated without PRP served as control group. Statistical analysis was done by Welch 2-sample t test and mixed linear model testing. RESULTS: In the coronal specimen portions, mean values for newly formed bone area, biomaterial area and marrow space of 32.2% ± 10.4%, 20.1% ± 13.0%, and 47.7% ± 8.5% were found with PRP, respectively. In the control group the corresponding values were 27.6% ± 13.4%, 20.3% ± 12.9%, and 52.1% ± 9.3%. In the apical specimen portions in the PRP group, the newly formed bone area, biomaterial area, and marrow space was 25.7% ± 15.0%, 23.4% ± 14.9%, and 50.9% ± 12.5%, respectively. The corresponding values in the control group were 17.0% ± 8.6%, 34.5% ± 11.2%, and 48.5% ± 8.5%. CONCLUSIONS: Statistical evaluation of the samples proved significantly better overall resorption of algae-derived hydroxyapatite AlgOss/C Graft/Algipore and increased new bone formation when PRP was used, especially in the apical region.

Functional outcome after surgical treatment of orbital floor fractures.

In the present article, the authors want to present the results of a retrospectively evaluated consecutive series of patients with surgically treated isolated orbital floor fractures (OFF; "blow-out fractures") concerning the functional outcome after OFF and give detailed recommendations based on the clinical and radiological findings. A series of 60 patients with isolated OFF over a 5-year period needing surgically repair at the same institution were evaluated. Patient data were analysed in terms of preoperative and postoperative clinical parameters and radiological findings. The analysed parameters were type of fracture, diplopia, gaze restriction, enophthalmos, materials used for repair, surgical approach and timing of the surgical intervention. Burst type fractures were more often found than punched-out fractures. The most frequently used surgical approach was a preseptal transconjunctival approach. An overall decrease of gaze restriction (93%), diplopia (89%) and enophthalmos (86%) was observed. According to the fracture size, we used Ethisorb patches in smaller fractures and resorbable or titanium meshes or autologous bone in larger fractures in most cases. Patients who underwent surgery more than 7 days after the trauma showed better results with regard to an improvement of diplopia and motility disturbances than patients who were treated immediately. In indicated cases, the surgical repair of OFF leads to very good results if the anatomical and functional properties of the orbit and its contents are respected. The applied strategy and means presented in our study proved of value and can therefore be recommended.