Tobias Fretwurst

Metal elements in tissue with dental peri-implantitis: a pilot study.

OBJECTIVES Dental peri-implantitis is characterized by a multifactorial etiology. The role of metal elements as an etiological factor for peri-implantitis is still unclear. The aim of this study was to investigate the incidence of metal elements in bone and mucosal tissues around dental Grade 4 CP titanium implants with signs of peri-implantitis in human patients. METHODS In this prospective pilot study, all patients were enrolled consecutively in two study centers. Bone and soft tissue samples of patients with peri-implantitis with indication for explantation were analyzed for the incidence of different elements (Ca, P, Ti, Fe) by means of synchrotron radiation X-ray fluorescence spectroscopy (SRXRF) and polarized light microscopy (PLM). The existence of macrophages and lymphocytes in the histologic specimens was analyzed. RESULTS Biopsies of 12 patients (seven bone samples, five mucosal samples) were included and analyzed. In nine of the 12 samples (75%), the SRXRF examination revealed the existence of titanium (Ti) and an associated occurrence with Iron (Fe). Metal particles were detected in peri-implant soft tissue using PLM. In samples with increased titanium concentration, lymphocytes were detected, whereas M1 macrophages were predominantly seen in samples with metal particles. CONCLUSION Titanium and Iron elements were found in soft and hard tissue biopsies retrieved from peri-implantitis sites. Further histologic and immunohistochemical studies need to clarify which specific immune reaction metal elements/particles induce in dental peri-implant tissue.

Long-term retrospective evaluation of the peri-implant bone level in onlay grafted patients with iliac bone from the anterior superior iliac crest

OBJECTIVE The purpose of the present study was to evaluate crestal bone level changes around dental implants after iliac bone augmentation in the long term. MATERIAL AND METHODS A total of 32 partially edentulous/edentulous patients (mean age, 52 years; range, 22-70 years) and a remaining bone volume of less than 5 mm of the alveolar ridge underwent maxillary or mandibular iliac bone graft augmentation. All patients received spaced standardized radiological examination for evaluation of peri-implant crestal bone loss. RESULTS The grafting procedure was successfully performed in all patients. A total of 150 implants were placed. The mean observation period was 69 months (range, 12-165 months; success rate for maxilla, 96%; success rate for mandible, 92%). The mean amount of crestal bone loss after 10 years was 1.8 mm. A significant difference between gender and crestal bone loss was shown, but no influence was found regarding the implant system, diameter of implant, and age of the patients. CONCLUSION In patients with atrophic jaws, a sufficient long-term reconstruction can be achieved with the combination of iliac onlay grafting and dental implants. The results demonstrate high success rates and a stable peri-implant bone level in the long term.

Comparison of four different allogeneic bone grafts for alveolar ridge reconstruction: a preliminary histologic and biochemical analysis

OBJECTIVES Allograft material for alveolar ridge reconstruction is quite promising and appears to be as equally successful as bone autograft material. The aim of the present study was to compare four different allogeneic bone grafts in terms of their histologic structure and DNA content before grafting. STUDY DESIGN Four allograft specimens from different suppliers were analyzed histologically, and the DNA content was analyzed before clinical use of the allografts. RESULTS Organic tissue remnants were detected in all of the evaluated samples. In the present samples adipocytes, fibroblasts, osteocytes, and chondrocytes were identified and DNA isolation and purification was possible. CONCLUSION Demineralized freeze-dried allogeneic bone transplants can stimulate new bone formation and are a viable alternative to bone autograft material. However, the well-tolerated use of allograft material in regard to our findings should be further investigated.

Recurrence rate and shift in histopathological differentiation of oral squamous cell carcinoma – A long-term retrospective study over a period of 13.5 years

OBJECTIVE Little information is available as to whether recurrences of oral squamous cell carcinoma (OSCC) show different histopathological grades than the primary tumor and whether postoperative radiotherapy (PORT) influences the grade of differentiation in the case of recurrence. The objective of this study was the evaluation of recurrence rates and change in differentiation. MATERIAL AND METHODS This retrospective, single-institution cohort study included surgically treated OSCC patients over a 13-year period (2000-2013). The relationship among tumor size, lymph node metastases, and recurrence rate of OSCC was investigated. Primary tumor differentiation was compared with differentiation of recurrence. RESULTS A total of 429 patients (277 men and 152 women) were included in this study. Of these, 124 (28.9%) received PORT. The incidence of primary cervical metastases increased significantly with tumor size (p < 0.001). Recurrence developed in 82 patients (19.1%). Stage T1/T2 showed a significantly lower recurrence rate than stage T3/T4 (16.3% vs. 30.2%) (p < 0.01). A total of 23 (30.7%) patients with recurrence showed a change in differentiation. CONCLUSION Increasing primary tumor size correlates with incidence of cervical metastases and recurrence rate. Initial cervical metastases show no effect on recurrence rates. Differentiation of primary tumor does not correlate with the recurrence rate. The majority of recurrences show consistent histopathological grading.

Dentoalveolar reconstruction: modern approaches.

Purpose of reviewA variety of bone grafting materials is available to facilitate the augmentation of defective alveolar ridges. This review evaluates current literature regarding bone grafting materials with emphasis on autologous and allogeneic bone block augmentation. Recent findingsAutogenous bone is a reliable grafting material providing predictable long-term results with high implant survival/success rates and low morbidity rates. The resorption properties of the iliac crest are well known and are compared with calvarial grafts more prominent. Recent studies demonstrated surgical techniques to prevent graft resorption after iliac crest grafting. Allogeneic block graft and implant survival rates appear promising in short-term clinical studies. SummaryAt this stage, iliac crest remains the gold standard in large alveolar bone defects. Autogenous material is not a panacea; however, none of the available materials can currently surpass it. Rather, each material has its specific advantage for certain indications. Evident long-term studies of allogeneic bone grafting are lacking. Detected cells in allogeneic bone substitute material are positive for major histocompatibility complex classes I and II. Despite the promising clinical results achieved with allogeneic bone grafts, the current literature lacks sufficient data on antigenicity.

The impact of force transmission on narrow-body dental implants made of commercially pure titanium and titanium zirconia alloy with a conical implant-abutment connection: An experimental pilot study

PURPOSE The purpose of this study was to visualize the mode and impact of force transmission in narrowdiameter implants with different implant-abutment designs and material properties and to quantify the displacement of the abutment. MATERIALS AND METHODS Narrow-diameter implants from two manufacturers were examined: Astra 3.0-mm-diameter implants (Astra OsseoSpeed TX; n = 2) and Straumann Bone Level implants with a 3.3-mm diameter made of commercially pure titanium (cpTi) Gr. 4 (n = 2) and 3.3-mm TiZr-alloy (n = 2; Bone Level, Straumann) under incremental force application using synchrotron radiography (absorption and inline x-ray phase-contrast) and tomography. RESULTS During loading (250 N), Astra 3.0 and Bone Level 3.3- mm implants showed a deformation of the outer implant shoulder of 61.75 to 95 μm independent of the implant body material; the inner implant diameter showed a deformation of 71.25 to 109.25 μm. A deformation of the implant shoulder persisted after the removal of the load (range, 42.75 to 104.5 μm). An angulated intrusion of the abutment (maximum, 140 μm) into the implant body during load application was demonstrated; this spatial displacement persisted after removal of the load. CONCLUSION This study demonstrated a deformation of the implant shoulder and displacement of the abutment during load application in narrow-diameter implants.

Various Radiographic Appearances of Fibrous Dysplasia in the Mandible - A Case Report

Introduction: Fibrous dysplasia appears in a clinically and radiologically variable way. Radiographic diagnostic is an important factor for final diagnosis especially as this rare lesion is often observed accidently in dental radiographic examinations. Therefore, the present case report demonstrates deviating clinical and radiological manifestations of monostotic and polyostotic forms of fibrous dysplasia (FD) in the facial area and its impact on dental and surgical therapy. Presentation of case: In the first patient, showing a monostotic form a hard, non-compressive swelling in the lower incisor area was detectable and radiographic investigation showed a “ground glass”-like radiopacity in the lower mandible. A surgical reduction of the process and a biopsy were indicated due to progression of the lesion and the development of aesthetic impairment at a young age. In the second patient, with a polyostotic manifestation, radiographic investigation revealed mixed heterogeneous sclerotic areas in the left mandibular angle and a “ground glass”-like pattern and osteolyses spreading out from the sphenoid sinus. A biopsy was obtained to confirm the radiological diagnosis without complete removal of the diseased bone. Conclusion: The two cases demonstrate the strongly varying clinical and radiological appearances of craniofacial FD and underline why it poses a challenge to the medical and dental practitioner. Furthermore, the present case report is discussing different diagnostic and therapy concepts according to different forms of FD and the consequences for dental therapy. Therapy strategies should always be determined by the progression and dimension of the disease and requires close interdisciplinary cooperation.