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 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.

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.

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.

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.

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.

Histological Analysis of an Implant Retrieved from a ß-Tricalcium Phosphate Graft after 4 Years: A Case Study.

We describe the retrieval of a dental implant device that had been successfully osseointegrated for more than 4 years. After obtaining an informed patient consent, the device was retrieved for retreatment purposes from its position in a ß-tricalcium phosphate (ß-TCP) grafted sinus floor. The sinus floor augmentation, using ß-TCP, had been performed in conjunction with the original implant placement, which in turn enabled the histological evaluation of specific regions of interest that were comprised of either grafted or native bone. Radiographs documented the rehabilitated area before and after grafting. The osteogenic events that occurred during the 4-yr-period depict the interplay of implant, synthetic graft material, and native bone in a dynamic process of osteogenesis, ongoing bone maturation, and remodeling that led to the development of haversian-like bone morphology. Two distinct areas were observed histologically, wherein osteointegration occurred uneventfully in both native bone and areas of grafted bone. Of particular interest was the presence of multiple remodeling sites of lamellar bone that could be seen between the plateaus-healing chambers-in which bone eventually evolved into a haversian cortical-like configuration.

Matrix-associated chondrocyte transplantation for reconstruction of articulating surfaces in the temporomandibular joint: a pilot study covering medium- and long-term outcomes of 6 patients.

OBJECTIVE: Matrix-associated chondrocyte transplantation is routinely used in joints of the extremities but not in the temporomandibular joint (TMJ). STUDY DESIGN: We report the first case series in 7 patients of a tissue engineering approach to regenerate severely degraded articulating surfaces in the TMJ by simultaneously completely resurfacing both the mandibular condyle and the articular eminence/glenoid fossa with a commercially available collagen sponge seeded with autologous cells stabilized within a fibrin matrix. To facilitate healing, we temporarily employed a silicone membrane to protect the engineered tissues. The indications for surgery were posttraumatic fibro-osseous ankylosis, ankylosing osteoarthritis, or late-stage osteoarthritis. RESULTS: Six of the patients were recalled for follow-up after 3 years 6 months to 12 years 1 month. The maximum incisal opening was 18.2 ± 9.2 mm (range, 9-33 mm) before and 31.2 ± 13.6 mm (range, 12-47 mm) at the latest follow-up. Histologic specimens taken at 4 months showed beginning differentiation of fibrocytes into chondrocytes, whereas at 3 and 11 years, mature hyaline cartilage-not typical for the TMJ-was present. CONCLUSIONS: We conclude that the reconstruction of TMJ surfaces by matrix-associated chondrocyte transplantation may become a routine method for cartilage regeneration in the TMJ in the future.

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.

The incisal foramen as a means of insertion for one of three ultra-short implants to support a prosthesis for a severely atrophic maxilla - A short-term report.

As a continuation of our prospective cohort study for a total of 18 patients with 72 implants in severely atrophic maxillae corresponding to Cawood and Howell class V and VI (1988) [1] with four 4.0 × 5.0 mm ultrashort locking taper implants Ewers et al., 2018 [2], we now present a prospective cohort study with a total of 9 patients. The special feature of this newly modified study is the reduction of the number of implants to only three 4.0 × 5.0 mm or 4.5 × 6.0 mm or 5.0 × 6.0 mm calcium phosphate-coated Bicon Integra CP implants. Reducing the number of implants is possible by inserting the middle implant into the incisal foramen and the nasopalatine canal. All patients were restored with metal-free prostheses made of a glass fiber-reinforced hybrid resin material. Neither were any implants lost during the observation period, nor did any patient experience any sensory alteration due to the placement of an implant into the nasopalatine canal. Three implants were sufficient in all patients to stabilize their 12-unit prosthesis.

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.

Split-thickness flap with a semicircular punched-ridge pedicled periosteal flap for implant restoration in highly atrophic patients: a technical note.

Attached gingiva is a crucial aspect of healthy peri-implant tissue. Severely atrophied jaws have minimal quantities of attached gingiva. Any surgical procedure bears the potential risk of further loss of attached gingiva. The split-thickness flap described here provides excellent access. Using a biopsy punch, the periosteum is easily cut in semicircular fashion on the labial surface of the bone so that it remains pedicled on the lingual or palatal ridge. The split-thickness flap permits fixation of the gingival flap to the periosteum. The periosteal flap is closed with sutures to achieve soft tissue closure over the implants even in case of simultaneous vestibuloplasty.

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.

High neutrophil-to-lymphocyte ratio is an independent marker of poor disease-specific survival in patients with oral cancer.

With growing evidence on the role of inflammation in carcinogenesis, the presence of a systemic inflammatory response has been proposed as having prognostic significance in a wide range of cancers. The aim of the study was to assess the value of pretreatment neutrophil-to-lymphocyte ratio (NLR) in predicting disease-specific survival (DSS) in patients with oral cancer undergoing preoperative chemoradiotherapy. A cohort of 97 patients with locally advanced oral squamous cell carcinoma receiving preoperative chemoradiotherapy was retrospectively examined. The impact of NLR and other potential prognostic factors on DSS was assessed with the Kaplan-Meier method and multivariate Cox regression analysis. Sixty-nine patients had a high pretreatment NLR, with NLR > 1.9 considered as high according to receiver operating characteristic curve analysis. In univariate analysis, high pretreatment NLR (p = 0.018), positive perineural invasion (p < 0.001) and advanced pathologic TNM stage after neoadjuvant therapy (p < 0.001) were predictive of shorter DSS. In multivariate analysis, advanced pathologic TNM stage after neoadjuvant therapy (HR 1.71, 95 % CI 1.17-2.48, p = 0.005), positive perineural invasion (HR 3.67, 95 % CI 1.11-12.13, p = 0.033) and high pretreatment NLR (HR 10.37, 95 % CI 1.28-84.08, p = 0.029) remained independently associated with poor DSS. A high pretreatment NLR is a significant independent predictor of shorter DSS in patients with oral cancer receiving preoperative chemoradiotherapy.

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.

Survival of patients with pathologic T0N+ oral and oropharyngeal cancer after neoadjuvant therapy and surgery: the minority report.

OBJECTIVES: Treatment outcome of patients with oral and oropharyngeal squamous cell carcinoma (OOSCC) achieving complete pathologic response at the primary site (ypT0) but incomplete response in loco-regional lymph nodes after preoperative chemoradiation (ypN+) is poorly described in the literature. This study's objective was to assess the survival of patients with OOSCC with ypT0N+ disease. STUDY DESIGN: 176 patients with primary locally advanced OOSCC undergoing preoperative chemoradiotherapy were stratified according to the pathologic TNM classification into 6 groups: ypT0N0M0 (46%), ypT0N+M0 (10%), ypTNM I (24%), ypTNM II (4%), ypTNM III (6%), and ypTNM IV (10%). RESULTS: Three-year overall survival (OS) and recurrence-free survival (RFS) rates for the ypT0N+M0 group were both 61.8% and were similar to those of the ypTNM I group (OS 62.4%; RFS rate of 59.2%). CONCLUSIONS: Survival analyses showed that patients with OOSCC with ypT0N+ disease have a similar prognosis to those with pathologic TNM stage I.

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.