Development of a porcine training model for microvascular fasciocutaneous free flap reconstruction.

BACKGROUND: In reconstructive surgery, improvements are needed in the effective teaching of free flap surgery. There is a need for easily accessible and widely available training without high financial costs or ethical concerns while still providing a realistic experience. Our aim was to develop an appropriate training model for microvascular flaps. METHODS: We identified pig head halves as most appropriate regarding availability, cost, and realism. These accrue largely by the food industry, so no animals need to be sacrificed, making it more ethical from an animal welfare perspective. We evaluated the suitability as flap donor site and analyzed the vascular anatomy of 51 specimens. RESULTS: Anatomical evaluation revealed a reliable and constant vascular anatomy, allowing the design of a flap model that can effectively illustrate the entire process of microvascular flap surgery. The process was divided into 6 key steps. The flap can be harvested after marking the vascular pedicle 5.3 cm from the lateral corner of the mouth. Skin island design and subsequent tissue dissection follow until a fasciocutaneous flap is raised, similar to a radial flap. Upon completion of flap harvesting, it can be freely transferred for defect reconstruction. Microvascular anastomosis can be performed on recipient vessels in the cervical region, and the difficulty can be individually adjusted. CONCLUSIONS: The developed training model is a reasonable compromise in terms of surgical realism, availability, didactic value, and cost/time effectiveness. We believe it is a powerful and effective tool with high potential for improving surgical education and training.

Comparison of the 7th and revised 8th UICC editions (2020) for oral squamous cell carcinoma: How does the reclassification impact staging and survival?

Since its introduction in 1968, the TNM (tumor, node, metastasis) classification established by the International Union Against Cancer has provided a consistent framework for staging of oral squamous cell carcinoma (OSCC). The introduction of the 8th edition in 2017 brought about significant modifications, encompassing the integration of depth of invasion (DOI) and extranodal extension (ENE) into the T and N classifications. Further, the UICC the criteria for the T3 and T4a categories were amended in 2020. This study aimed to evaluate the impact of reclassification on staging and, subsequently, the survival of patients with OSCC. Primary OSCCs from 391 patients were classified according to the 7th and revised 8th UICC editions (2020). Stage migration was assessed, and stage-specific progression-free survival (PFS) and overall survival (OS) were evaluated using the Kaplan-Meier method. The log-rank test was used to compare the different stages. Cox-proportional hazard modeling was used to compare the two editions. Incorporating the DOI into the T classification resulted in an upstaging of 77 patients, constituting 19.69% of the cohort. In addition, 49 (12.53%) patients experienced an upstaging when considering ENE in the N classification. Consequently, 103 patients underwent upstaging in UICC staging, accounting for 21.74% of cases. Upstaging mainly occurred from stage III to IVA (26.92%) and from stage IVA to IVB (31.78%). Upon comparing the categories in survival analysis, significant differences in OS and PFS were especially observed between stage IVB and lower stages. When examining the hazard ratios, it became evident that UICC 8 stage IVB is burdened by a 5.59-fold greater risk of disease progression than stage I. Furthermore, UICC 8 stage IVB exhibits a 3.83 times higher likelihood of death than stage I disease. We demonstrated significant stage migration from the 7th to the revised 8th UICC edition. Overall, incorporating DOI and ENE into the T and N classifications represents a substantial clinical advancement, leading to a more accurate staging of OSCC patients. Both staging systems exhibited statistically significant discrimination between stages; however, the 8th UICC edition allowed for a more precise categorization of patients based on their prognosis and led to enhanced hazard discrimination, particularly within higher stages.

Occult metastasis is no burden factor in oral squamous cell carcinoma patients when adhering to a standardized approach in neck dissection.

OBJECTIVES: Management of the neck in patients with oral squamous cell carcinoma (OSCC) is pivotal to oncologic control and survival. However, there is controversy regarding necessity of neck dissection (ND) in patients with clinically node-negative neck. We aimed to assess risk factors for occult metastasis and to explore whether the presence of occult lymph node metastases (LNMs) has an impact on recurrence and survival. MATERIAL AND METHODS: A retrospective cohort study was performed including patients with primary OSCC who underwent radical tumor resection and ND in a high-volume center adhering to the prevailing German guideline. The ND was performed according to a standardized approach. RESULTS: Four hundred twenty-one patients with primary surgically treated OSCC were included. The incidence of occult metastasis was 14.49%. A pathological T stage > 1 (multivariate analysis, odds ratio (OR) 3.958, p = 0.042) and the presence of extranodal extension in LNMs (multivariate analysis, OR 0.287, p = 0.020) were identified as independent risk factors for occult metastasis. When comparing patients with and without occult metastasis, there were no significant differences in terms of progression-free survival (log-rank, p = 0.297) and overall survival (log-rank, p = 0.320). There were no cases of ipsilateral neck recurrence. One patient developed contralateral neck metastasis; however, he initially presented with a unilateral pT1 pN0 tumor. CONCLUSIONS: Overall, our findings suggest that conducting a standardized approach in ND should be applied in terms of management of the neck in order to maintain survival rates and to prevent neck recurrence in OSCC patients. CLINICAL RELEVANCE: None of the risk factors for occult metastasis can be reliably assessed preoperatively. Although elective ND does not guarantee the complete prevention of neck recurrence, it increases the likelihood of either timely removal of micrometastases or strengthens the justification for adjuvant therapy. Consequently, this approach leads to improvements in clinical outcomes.

Diagnostic accuracy of contrast-enhanced computed tomography in assessing cervical lymph node status in patients with oral squamous cell carcinoma.

OBJECTIVE: Accurate preoperative prediction of lymph node (LN) status plays a pivotal role in determining the extension of neck dissection (ND) required for patients with oral squamous cell carcinoma (OSCC). This study aims to evaluate the diagnostic accuracy of contrast-enhanced computed tomography (CT) in detecting LN metastases (LNMs) and to explore clinicopathological factors associated with its reliability. METHODS: Data from 239 patients with primary OSCC who underwent preoperative CT and subsequent radical surgery involving ND were retrospectively reviewed. Suspicious LNs were categorized into three groups: accentuated (< 10 mm), enlarged (≥ 10 mm), and melted. Statistical analysis encompassing correlation and comparative analysis, and determination of sensitivity, specificity, PPV, and NPV were performed. RESULTS: Overall, sensitivity was significantly higher in the accentuated LNs group (83.54%) compared to the melted LNs group (39.24%, p < 0.05, t test). Conversely, specificity was significantly higher in the melted LNs group (98.19%) compared to the accentuated LNs group (55.15%, p < 0.05, t test). Accentuated LNs exhibited a false negative rate of 13.00%. False positive rates were 51.80%, 30.26% and 8.82%, respectively. Diagnostic accuracy for detecting LNMs in level IIa and IIb exceeded that of level III. Patients with solely accentuated LNs were more likely to have a small, well-differentiated tumor. However, no distinctions emerged in terms of the occurrence of T4 tumors among the three groups. CONCLUSION: CT proves sufficient to predict LNMs in patients with OSCC. Looking ahead, the potential integration of artificial intelligence and deep learning holds promise to further enhance the reliability of CT in LNMs detection. However, this prospect necessitates further investigation.

A Treatment Approach for Carotid Blowout Syndrome and Soft Tissue Reconstruction after Radiotherapy in Patients with Oral Cancer: A Report of 2 Cases.

BACKGROUND: This retrospective case series study aims to demonstrate a salvage technique for the treatment of carotid blow-out syndrome (CBS) in irradiated head and neck cancer patients with a vessel-depleted neck. METHODS: Between October 2017 and October 2021, two patients (N = 2) with CBS were treated at our institution in a multidisciplinary approach together with the Department of Vascular Surgery. Patients were characterized based on diagnoses, treatment procedures, and the subsequent postoperative course. RESULTS: Surgical emergency intervention was performed in both cases. The transition zone from the common carotid artery (CCA) to the internal carotid artery (ICA) was resected and reconstructed with a xenogic (case 1) or autogenic (case 2) interposition (end-to-end anastomosis). To allow reconstruction of the vascular defect, an additional autologous vein graft was anastomosed to the interposition graft in an end-to-side technique, allowing arterial anastomosis for a free microvascular flap without re-clamping of the ICA. Because of the intraoperative ICA reconstruction, none of the patients suffered a neurological deficit. CONCLUSIONS: The techniques presented in the form of two case reports allow for acute bleeding control, cerebral perfusion, and the creation of a vascular anastomosis option in the vessel-depleted neck.

Peculiarities in the panoramic radiograph of patients with secondary hyperparathyroidism due to terminal renal disease: a radiologic controlled comparative study.

OBJECTIVES: The present radiological observational controlled study aims to evaluate the impact of secondary hyperparathyroidism (SHPT) due to chronic kidney disease (CKD) as well as the duration of dialysis on the mineralization of the mandible by standardized qualitative evaluation of digital panoramic radiographs. METHODS: Panoramic radiographs of CKD patients with SHPT and healthy controls were used for the qualitative analysis of the mandibular cortical index (MCI), the trabecular bone pattern (TBP), and calcification and resorption foci. Radiomorphometric indices were correlated to biochemical parameters and the duration of dialysis using the Spearman Rho test. Group comparisons were conducted using the Mann-Whitney U test and Fisher's exact test at a significance level of α ≤ 0.05. Interrater reliability of two physicians was estimated using Cohen's kappa. RESULTS: Inclusion and exclusion criteria were fulfilled by N = 41 patients. Statistically significant differences in the MCI (p < 0.001) as well as the TBP (p = 0.002) could be detected for the experimental group in comparison to the healthy control group. Focusing on calcification and resorption foci, no statistically significant difference could be detected between the groups (p = 0.244). The level of the detected parathyroid hormone (PTH) significantly correlated with TBP (Rho = 0.338; p = 0.031), while no significant relationship between TBP and the duration of the dialysis could be found. CONCLUSIONS: Patients with SHPT due to CKD show statistically significant bone changes in the panoramic radiograph, whereby the grade of trabecular bone change correlates to PTH values.

Retrospective three-dimensional analysis of bone resorption volumes of free microvascular scapular and fibular grafts.

Defects in head and neck regions are standardly treated with microvascular grafts, such as free scapular (SFF) and fibular flaps (FFF), which are subject to a certain amount of bone resorption over time. The aim of this study was the 3-dimensional evaluation of bone resorption volume in both grafts. Over a period of 10 years, computed tomograms (CT) of patients with mandibular reconstructions with SFFs and FFFs were examined. The respective grafts were segmented as well as 3-dimensionally measured. Furthermore, factors such as gender, age, nicotine abuse, previous disease with type 2 diabetes, and adjuvant therapies, were examined for their influence. A total of 211 CT scans from 67 patients (40 SFFs and 27 FFFs) were included in the study. SFFs showed slightly higher median bone volumes (87.60% at 730 days and 86.55% at 1500 days) than FFFs (84.40% at 730 days and 82.10% at 1500 days). When final volumes were considered, FFFs had higher mean volume values (88.22%) than SFFs (83.82%), with significant correlation between resorption volume and time progression (r = 0.357, p = 0.024). All previously mentioned factors had no significant effect on bone resorption. Bone volumes of FFFs showed postoperative volume reductions similar to those of SFFs, with isolated SFFs having markedly lower volume values. The choice of a microvascular graft for reconstruction in the mandible proves difficult regarding bone resorption. The presented results may support decisions about future transplantations.

Frequency of the necessity of dentoalveolar surgery or conservative treatment in patients before kidney transplantation depending on the duration of dialysis and causative nephrological disease.

OBJECTIVES: This retrospective study evaluates intraoral surgical and conservative treatment need in patients with a chronic kidney end-stage disease, depending on the duration of dialysis treatment and the causative nephrological disease. MATERIAL AND METHODS: This study is based on data of patients referred to the Department of Oral and Maxillofacial Surgery of the University Hospital Erlangen, Germany, prior to kidney transplantation between January 2015 and March 2020. The necessity for oral surgical or dental therapy was determined by clinical and radiological examinations. Data on renal replacement therapy, cause of underlying renal disease, lifestyle, and general health were collected. RESULTS: Data of N = 89 patients demonstrated that surgical treatment need depends on dialysis duration (p = 0.042). Patients, who had been dialyzing for 2 to 3 years showed the highest need for surgical intervention (80.0%; p = 0.024), followed by dialysis patients with a dialysis time of more than 3 years (48.1%). Similarly, dialysis patients in the second or third year of dialysis had the highest need for conservative treatment (73.3%; p > 0.05), followed by 55.6% of dialysis patients in the third year of dialysis. CONCLUSIONS: Operative and conservative treatment is essential to optimize subsequent kidney transplantation. The greatest necessity could be detected for patients in the second and third years of dialysis. CLINICAL RELEVANCE: Oral health addressing surgical and conservative treatment need depends on the duration of dialysis in patients with a chronic kidney end-stage disease.

Oral health of patients suffering from end-stage solid organ insufficiency prior to solid organ re-transplantation: a retrospective case series study.

BACKGROUND: The oral health of organ transplanted patients before organ re-transplantation is largely unknown. This retrospective clinical study evaluates the necessity for intraoral surgical intervention and/or conservative treatment in candidates awaiting organ re-transplantation, both for graft failure and for reasons of another upcoming solid organ transplantation (renal or non-renal). METHODS: From January 2015 to March 2020 n = 19 transplant recipients in evaluation on the waiting list for solid organ re-transplantation could be included in the retrospective case series study. Using clinical and radiological examinations, necessity for oral surgical or conservative dental treatment was evaluated. On the basis of anamnesis data, current kidney function, renal replacement treatment (RRT), and medication, a risk profile for several patient subgroups was created. RESULTS: The clinical and radiological examinations showed a conservative and/or surgical treatment need in n = 13 cases (68.42%). In n = 7 cases (36.84%) surgical intervention was recommended due to residual root remnants (n = 5), unclear mucosal changes (n = 1), and periimplantitis (n = 1). In n = 16 recipients (84.2%) RRT (n = 15 hemodialysis; n = 1 peritoneal dialysis) had been performed. N = 14 recipients (73.68%) received immunosuppressants. In n = 1 patient (5.3%) displayed intraoral and n = 4 patients (21.1%) extraoral neoplasms due to drug-induced immunosuppression. CONCLUSIONS: Solid organ transplant recipients with renal failure present a complex treatment profile due to a double burden of uremia plus immunosuppressants. In cases of surgical treatment need a hospitalized setting is recommended, where potentially necessary follow-up care and close cooperation with disciplines of internal medicine is possible in order to avoid surgical and/or internal complications.

The effect of polyethylenglycol gel on the delivery and osteogenic differentiation of homologous tooth germ-derived stem cells in a porcine model.

OBJECTIVES: The aim of this study was to investigate if bone regeneration can be promoted by homologous transplantation of STRO-1 sorted (STRO-1+) porcine tooth germ mesenchymal stem cells (TGSCs) with the combination of polyethylenglycol (PEG)-based hydrogel and biphasic calcium phosphate (BCP) scaffolds. MATERIAL AND METHODS: TGSCs were isolated from impacted third molars of domestic pigs. Nine critical-sized defects were created as (1) untreated defect; filled with (2) autogenous bone; (3) BCP + PEG; (4) BCP + PEG + unsorted TGSCs; (5) BCP + unsorted TGSCs; (6) BCP + PEG + STRO-1-sorted TGSCs; (7) BCP + STRO-1-sorted TGSCs; (8) BCP + PEG + osteogenic induced unsorted TGSCs; and (9) BCP + PEG + osteogenic induced STRO-1-sorted TGSCs in 20 domestic pigs. CM-DiI labelling was used to track cells in vivo. Histomorphometric assessment of new bone formation was achieved by toluidine blue O staining and microradiography after 1, 2, 4 and 12 weeks posttransplantation. RESULTS: Complete healing was achieved in all defects although defects with PEG hydrogel presented better bone formation while STRO-1+ and unsorted TGSCs showed similar ability to form new bone after 12 weeks. Transplanted cells were seen in defects where PEG hydrogel was used as carriers in contrast to defects treated with cells and only bone grafts. CONCLUSIONS: PEG hydrogel is an efficient carrier for homologous stem cell transplantation. TGSCs are capable of promoting bone healing in critical-sized defects in combination with bone graft and PEG hydrogel. CLINICAL RELEVANCE: This study provides information about the importance of the delivery vehicle for future translational stem cell delivery approaches.

Correction to: Osseous ingrowth in allogeneic bone blocks applied for vertical bone augmentation: a preclinical randomized controlled study.

In the article by Möst et al., entitled "Osseous ingrowth in allogeneic bone blocks applied for vertical bone augmentation: a preclinical randomized controlled study.

A new standardized critical size bone defect model in the pig forehead for comparative testing of bone regeneration materials.

OBJECTIVES: The preclinical study aimed to establish a standardized preclinical model to investigate osseous graft consolidation in defect configurations of limited regenerative capacity. MATERIAL AND METHODS: Critical size defects (CSD) were prepared and titanium tubes inserted for defect separation from local bone in the forehead area of 18 pigs. Defects were filled with demineralized bovine bone mineral (DBBM) or served as empty controls and were covered with a resorbable collagen membrane (CM) or left untreated. Six randomly selected pigs were sacrificed after 4, 8 and 12 weeks. Specimens were histologically and histomorphometrically analysed focusing on newly formed bone (NFB), demineralized bovine bone mineral (DBBM) and soft tissue (ST) proportions. RESULTS: Four weeks after defect preparation, no statistically significant difference concerning NFB quantity could be detected within the groups. Defects covered with the CM showed lower amounts of DBBM. After 6 and 12 weeks, defects augmented with DBBM in combination with a CM (8 weeks: 43.12 ± 4.31; 12 weeks: 43.05 ± 3.01) showed a statistically significant higher NFB rate compared to empty control defects covered with 8 weeks: 7.66 ± 0.59; 12 weeks or without a CM; 8 weeks: 8.62 ± 2.66; 12 weeks: 18.40 ± 2.40. CM application showed no significant impact on osseous defect regeneration or soft tissue formation. Superior NFB could be detected for basal aspect for several evaluation time points. CONCLUSIONS: The modification of CSD with titanium tubes represents a suitable model to imitate a one-wall defect regeneration situation. CLINICAL RELEVANCE: The established model represents a promising method to evaluate graft consolidation in one-wall defect configuration.

Osseous ingrowth in allogeneic bone blocks applied for vertical bone augmentation: a preclinical randomised controlled study.

OBJECTIVES: The aim of the present study was the qualitative and quantitative evaluation of osseous graft consolidation using allogeneic bone blocks for vertical bone augmentation in an animal model. MATERIAL AND METHODS: Standardised allogeneic and autologous bone blocks were fixed on the frontal skull of 20 adult female pigs and covered with a resorbable collagen membrane. Animals were sacrificed after 2 and 6 months. Specimens were histologically and histomorphometrically analysed focusing on the amount of vital bone, residual bone substitute material and connective tissue. Furthermore, the amount of expression of bone matrix proteins (collagen type I and osteocalcin) and de novo vessel formation (von Willebrand factor) were quantified by immunohistochemistry. RESULTS: Significantly more allogeneic bone blocks failed for both evaluation time points (p < 0.05). Allogeneic blocks showed significantly less vital bone with more connective tissue formation compared to autologous bone blocks. Increased vessel formation could be detected for both evaluation time points in the contact area of autologous bone with local bone. The expression of collagen type I and osteocalcin was significantly lower in the allogeneic bone graft. CONCLUSIONS: Allogeneic cancellous bone blocks showed a significantly higher failure rate compared to autologous bone blocks. Allogeneic bone blocks seemed to negatively affect bone formation or negatively influence the host in the long term, and increased connective tissue formation and block loss should be anticipated. CLINICAL RELEVANCE: In order to maintain patient safety and treatment success clinicians should be persuaded to make a conscious choice of the applied biomaterials with regard to their components and structure.

The influence of nanoporous anodic aluminum oxide on the initial adhesion of Streptococcus mitis and mutans.

The use of nanoscale surface modifications offers a possibility to regulate the bacterial adherence behavior. The aim of this study was to evaluate the influence of nanoporous anodic aluminum oxide of different pore diameters on the bacterial species Streptococcus mitis and Streptococcus mutans. Nanoporous anodic aluminum oxide (AAO) surfaces with an average pore diameter of 15 and 40 nm, polished pure titanium and compact aluminum oxide (alumina) samples as reference material were investigated. S. mitis and mutans were evaluated for initial adhesion and viability after an incubation period of 30 and 120 min. After 30 min a significantly reduced growth of S. mitis and mutans on 15 nm samples compared to specimens with 40 nm pore diameter, alumina and titanium surfaces could be observed (p < .001). Even after 120 min incubation there was a significant difference between the surfaces with 15 nm pore diameter and the remaining samples (p < .001). AAO surfaces with a small pore diameter have an inhibitory effect on the initial adhesion of S. mitis and mutans. The use of such pore dimensions in the area of the implant shoulder represents a possibility to reduce the adhesion behavior of these bacterial species.

Gingiva thickening with a porcine collagen matrix in a preclinical dog model: Histological outcomes.

AIM: To compare 10-month histological and immunohistological outcomes after soft tissue thickening around teeth with a porcine collagen matrix (CM) versus a subepithelial connective tissue graft (SCTG). MATERIAL AND METHODS: In eight beagle dogs, soft tissue thickening of the buccal gingiva of upper canines was performed with the SCTG or the CM. Connective tissue thickness (CTT) was histomorphometrically measured in the augmented regions. The augmented connective tissues were also histologically characterized and the collagen I and vascular endothelial growth factor (VEGF) expressions immunohistologically quantified. RESULTS: CTT significantly differed between groups (SCTG: 1.32 mm ± 0.44 mm; CM: 1.06 mm ± 0.27 mm; p = .008). Descriptive histological analyses revealed mature connective tissue that did not differ between groups. Immunohistological quantification of collagen I and VEGF expressions in the connective tissue also revealed no significant inter-group differences (collagen I: SCTG, 32.64% ± 7.09% vs. CM, 30.57% ± 7.83%; VEGF: SCTG, 39.06% ± 7.27% vs. CM, 37.15% ± 9.80%). CONCLUSION: SCTG is superior to CM with regard to CTT in this experimental model. The CM and the SCTG lead to comparable connective tissue quality ten months after connective tissue thickening.

Correction to: Anatomical locations in the oral cavity where surgical resections of oral squamous cell carcinomas are associated with a close or positive margin-a retrospective study.

The following note was inadvertently omitted from the published paper: This work was performed in (partial) fulfillment of the requirements for the first author's obtaining the degree Dr. med. dent.

Anatomical locations in the oral cavity where surgical resections of oral squamous cell carcinomas are associated with a close or positive margin-a retrospective study.

OBJECTIVES: This study aimed to identify anatomical areas where resections of oral squamous cell carcinomas (OSCC) are significantly associated with close or positive margins. MATERIALS AND METHODS: This retrospective study included 330 patients with a primary OSCC from 2010 to 2015. Patient and tumour data were categorised into three groups by R-status (R0 [clear], ≥ 5 mm, 185 patients [56.06%]; R1 [positive], < 1 mm, 24 patients [7.27%]; and R0 [close], 1-5 mm, 121 patients [36.67%]). RESULTS: Areas where resections were significantly associated with close or positive margins were the hard palate (p < 0.001), buccal mucosa (p = 0.03), floor of the mouth (p = 0.004), lower alveolar ridge (p = 0.01), retromolar triangle (p = 0.005), and dorsal tongue (p = 0.02). CONCLUSIONS: Anatomical areas were identified in the oral cavity where it is challenging to resect OSCCs with an adequate safety margin. CLINICAL RELEVANCE: These results may enable surgeons to achieve a postulated safe distance during tumour resection, leading to a survival benefit for patients.

The influence of different abutment materials on tissue regeneration after surgical treatment of peri-implantitis - a randomized controlled preclinical study.

OBJECTIVES: This study aimed to assess the impact of different abutment materials on peri-implant tissue regeneration after surgical treatment of peri-implantitis in a large animal model. MATERIAL AND METHODS: Titanium implants (n = 51) were inserted in the upper and lower jaw of eight beagle dogs and a peri-implant infection was induced. After two months the peri-implant infection was surgically treated and abutments with different surfaces (Ti-2: n = 14; CoCrMb: n = 13; Ag-modified Ti-4: n = 14; Ti-4 control: n = 10) were applied. Clinical attachment level (CAL), modified sulcus bleeding index (mBI), bleeding on probing (BoP), and the sulcus fluid flow rate (SFFR) were determined 4, 8, and 12 weeks after surgical treatment to document the peri-implant tissue reaction. RESULTS: Superior levels for CAL and mBI were found with the Ti-4 control and the Ag-modified abutments, with the Ag-modified abutments showing the best values after 12 weeks. Lowest SFFR values compared with the other treatment groups underlined the superior soft tissue reaction adjacent to Ag-modified abutments. After 12 weeks inferior CAL, SFFR, BOP and mBI values were documented for the Ti-2 surface. CONCLUSION: Within limitations of the study, Ag-modified abutments lead to superior tissue reactions. Further studies are needed to investigate the properties of abutment materials.

Peri-implant defect regeneration in the diabetic pig: A preclinical study.

OBJECTIVES: The study aims to establish a peri-implant dehiscence-type bone defect in a diabetic animal model of human bone repair and to quantify the influence of diabetes on peri-implant bone regeneration. MATERIAL AND METHODS: Experimental diabetes was induced in three domestic pigs by streptozotocin. Three animals served as healthy controls. After 12 months four standardized peri-implant dehiscence bone defects were surgically created in the ramus mandibulae. The animals were sacrificed after 90 days. Samples were histologically analyzed to quantify new bone height (NBH), bone-to-implant-contact (BIC), area of newly formed bone (NFB), bone-density (BD), and bone mineralization (BM) in the prepared defect (-D) and in a local control region (-L). RESULTS: After 90 days, diabetic animals revealed a significantly lower BIC (p = 0.037) and BD (p = 0.041) in the defect area (-D). NBH and BM-D differences within the groups were not significant (p > 0.05). Significant more NFB was measured in the healthy control group (p = 0.046). In the region of local bone BIC-L was significant less in the diabetic group (p = 0.028). In the local control region BD-L and BM-L was lower in the diabetic group compared to the healthy control animals (p > 0.05). CONCLUSION: Histological evidence indicates impaired peri-implant defect regeneration in a diabetic animal model.