Daniel Rothamel

Immunohistochemical characterization of guided bone regeneration at a dehiscence‐type defect using different barrier membranes: an experimental study in dogs

OBJECTIVES The aim of the present study was to evaluate immunohistochemically the pattern of guided bone regeneration (GBR) using different types of barrier membranes. MATERIAL AND METHODS Standardized buccal dehiscence defects were surgically created following implant bed preparation in 12 beagle dogs. Defects were randomly assigned to six different GBR procedures: a collagen-coated bone grafting material (BOC) in combination with either a native, three cross-linked, a titanium-reinforced collagen membrane, or expanded polytetrafluorethylene (ePTFE), or BOC alone. After 1, 2, 4, 6, 9, and 12 weeks of submerged healing, dissected blocks were processed for immunohistochemical (osteocalcin - OC, transglutaminase II - angiogenesis) and histomorphometrical analysis [e.g., bone-to-implant contact (BIC), area of new bone fill (BF)]. RESULTS In general, angiogenesis, OC antigen reactivity, and new bone formation mainly arose from open bone marrow spaces at the bottom of the defect and invaded the dehiscence areas along the implant surface and BOC. At 4 weeks, membranes supporting an early transmembraneous angiogenesis also exhibited some localized peripheral areas of new bone formation. However, significantly increasing BIC and BF values over time were observed in all groups. Membrane exposure after 10-12 weeks was associated with a loss of the supporting alveolar bone in the ePTFE group. CONCLUSION Within the limits of the present study, it was concluded that (i) angiogenesis plays a crucial role in GBR and (ii) all membranes investigated supported bone regeneration on an equivalent level.

Lateral ridge augmentation using particulated or block bone substitutes biocoated with rhGDF-5 and rhBMP-2: an immunohistochemical study in dogs.

OBJECTIVES The aim of the present study was to immunohistochemically evaluate lateral ridge augmentation using a particulated (BOG) or block (BOB) natural bone mineral biocoated with rhGDF-5 and rhBMP-2 in dogs. MATERIALS AND METHODS Three standardized box-shaped defects were surgically created at the buccal aspect of the alveolar ridge in each quadrant of eight beagle dogs. After 2 months of healing, the chronic-type defects were randomly allocated in a split-mouth design to either (i) BOG or (ii) BOB biocoated with (a) rhGDF-5 or (b) rhBMP-2, respectively. Uncoated grafts served as controls. After 3 and 8 weeks, dissected blocks were prepared for immunohistochemical [osteocalcin (OC)] and histomorphometrical analysis [e.g. area (mm(2)) of new bone fill (BF), newly formed mineralized (MT) and non-mineralized tissue (NMT)]. RESULTS rhBMP-2 biocoated BOG revealed significantly highest BF and MT values at 3 (upper and lower jaws - UJ/LJ - compared with BOG) and 8 weeks (UJ - compared with rhGDF-5). Biocoating of BOB using both rhGDF-5 and rhBMP-2 resulted in significantly increased MT values at 8 weeks (UJ/LJ - compared with BOB). In all groups, NMT adjacent to BOG and BOB scaffolds revealed pronounced signs of an OC antigen reactivity. CONCLUSIONS Within the limits of the present study, it was concluded that both rhGDF-5 and rhBMP-2 have shown efficacy; however, their bone regenerative effect was markedly influenced by the carrier.

Two‐year clinical results following treatment of peri‐implantitis lesions using a nanocrystalline hydroxyapatite or a natural bone mineral in combination with a collagen membrane

OBJECTIVES The aim of the present case series was to evaluate the 2-year results obtained following treatment of peri-implantitis lesions using either a nanocrystalline hydroxyapatite (NHA) or a natural bone mineral in combination with a collagen membrane (NBM+CM). MATERIAL AND METHODS Twenty-two patients suffering from moderate peri-implantitis (n=22 intra-bony defects) were randomly treated with (i) access flap surgery (AFS) and the application of NHA, or with AFS and the application of NBM+CM. Clinical parameters were recorded at baseline and after 12, 18, and 24 months of non-submerged healing. RESULTS Two patients from the NHA group were excluded from the study due to severe pus formation at 12 months. At 24 months, both groups revealed clinically important probing depth (PD) reductions (NHA: 1.5+/-0.6 mm; NBM+CM: 2.4+/-0.8 mm) and clinical attachment level (CAL) gains (NHA: 1.0+/-0.4 mm; NBM+CM: 2.0+/-0.8 mm). However, these clinical improvements seemed to be better in the NBM+CM group (difference between groups: PD reduction: 0.9+/-0.2 mm; CAL gain: 1.0+/-0.3 mm). CONCLUSION Both treatment procedures have shown efficacy over a period of 24 months, however, the application of NBM+CM may result in an improved outcome of healing.

Computer-assisted orthognathic surgery: waferless maxillary positioning, versatility, and accuracy of an image-guided visualisation display

There may well be a shift towards 3-dimensional orthognathic surgery when virtual surgical planning can be applied clinically. We present a computer-assisted protocol that uses surgical navigation supplemented by an interactive image-guided visualisation display (IGVD) to transfer virtual maxillary planning precisely. The aim of this study was to analyse its accuracy and versatility in vivo. The protocol consists of maxillofacial imaging, diagnosis, planning of virtual treatment, and intraoperative surgical transfer using an IGV display. The advantage of the interactive IGV display is that the virtually planned maxilla and its real position can be completely superimposed during operation through a video graphics array (VGA) camera, thereby augmenting the surgeons 3-dimensional perception. Sixteen adult class III patients were treated with by bimaxillary osteotomy. Seven hard tissue variables were chosen to compare (ΔT1-T0) the virtual maxillary planning (T0) with the postoperative result (T1) using 3-dimensional cephalometry. Clinically acceptable precision for the surgical planning transfer of the maxilla (<0.35 mm) was seen in the anteroposterior and mediolateral angles, and in relation to the skull base (<0.35°), and marginal precision was seen in the orthogonal dimension (<0.64 mm). An interactive IGV display complemented surgical navigation, augmented virtual and real-time reality, and provided a precise technique of waferless stereotactic maxillary positioning, which may offer an alternative approach to the use of arbitrary splints and 2-dimensional orthognathic planning.

Accuracy of cone beam computed tomography in assessing peri‐implant bone defect regeneration: a histologically controlled study in dogs

OBJECTIVE To assess the accuracy of cone-beam computed tomography (CBCT) in terms of buccal bone-wall configuration and peri-implant bone defect regeneration after guided bone regeneration (GBR). MATERIAL AND METHODS Titanium implants were inserted into standardized box-shaped defects in the mandible of 12 foxhounds. Defects of one side were augmented following the principle of GBR, while the other side was left untreated. Radiological evaluation was performed using CBCT and compared with histomorphometrical measurements of the respective site serving as a validation method. RESULTS Non-augmented control sites providing a horizontal bone width (BW) of<0.5 mm revealed a significantly lower accuracy between the radiological and the histological evaluation of the buccal defect depth (1.93 ± 1.59 mm) compared with the group providing a BW of >0.5 mm (0.7 ± 0.7 mm) (P<0.05, Mann-Whitney U-test). In GBR-treated defects, the subgroup <0.5 mm (1.49 ± 1.29 mm) revealed a significantly higher difference between CBCT and histology compared with >0.5 mm (0.82 ± 1.07) (P>0.05, Mann-Whitney U-test). However, a radiological discrimination between original bone, integrated and non-integrated bone substitute material was not reliable. Additionally, it was found that a minimum buccal BW of 0.5 mm was necessary for the detection of bone in radiology. CONCLUSION The evaluation of peri-implant bone defect regeneration by means of CBCT is not accurate for sites providing a BW of <0.5 mm. Moreover, a safe assessment of the success of the GBR technique is not possible after the application of a radiopaque bone substitute material.

Ridge augmentation using customized allogenic bone blocks: proof of concept and histological findings.

Aim: To evaluate handling and healing patterns of customized allogenic bone blocks for vertical and horizontal alveolar defect augmentation. Materials and Methods: In 2 patients, 3 combined horizontal and vertical post-foraminal mandibular defects were grafted using computer-aided design (CAD) trimmed individual block grafts, 3D-designed on preoperative computed tomography scans. After a healing period of 6 months, graft resorption was measured and bone trephines were taken in progress of implant bed preparation. Four months later, implants were restored with single crowns. Moreover, clinical and radiological implant parameters were assessed 6 and 12 months after restorative rehabilitation. Results: Uneventful healing was observed in 2 of the 3 cases. A partial exposure of 1 block after 8 weeks could be successfully treated by block reduction and application of a soft tissue graft. Histological evaluation revealed predictable bone formation within all augmented areas, and both patient satisfaction and long-term stability parameters were considered excellent. Conclusions: It was concluded that the application of individual CAD allografts supports bone formation at deficient sites with reduced patient morbidity, decreased surgery time, and high patient acceptance.

Impact of anxiety parameters on prospective and experienced pain intensity in implant surgery.

Purpose:To investigate the relationship between anxiety and pain perception in the context of implant surgery and to examine the impact of factors such as gender and surgery duration on anxiety and pain levels. Methods:One hundred twenty-one patients undergoing implant surgery evaluated their anxiety and pain levels by completing a set of 2 questionnaires at different points in time. Results:Both anxiety and pain levels were highest on the day of surgery and showed a significant decrease when evaluated retrospectively (P < 0.01; P < 0.05). Correlations were found between preoperative anxiety and expected pain levels (r = 0.19), pain peak and duration of pain (r = 0.79), and a nearly significant correlation between preoperative anxiety and duration of pain (r = 0.18). Women showed significantly higher levels of preoperative anxiety (P < 0.05) and expected pain (P < 0.05) than men. Conclusion:The results confirm a strong negative impact of increased preoperative anxiety levels on pain perception and the recovery process. Therefore, future research should focus on individual patients sources of dental anxiety to reduce its negative consequences.

Effects of various chair-side surface treatment methods on dental restorative materials with respect to contact angles and surface roughness

Available chair-side surface treatment methods may adversely affect prosthetic materials and promote plaque accumulation. This study investigated the effects of treatment procedures on three resin restorative materials, zirconium-dioxide and polyetheretherketone in terms of surface roughness and hydrophobicity. Treatments were grinding with silicon carbide paper or white Arkansas stone, blasting with prophylaxis powder and polishing with diamond paste. Surface roughness was assessed using confocal laser scanning. Hydrophobicity as measured by water contact angle was determined by computerized image analysis using the sessile drop technique. All of the specific surface treatments performed led to significant changes in contact angle values and surface roughness (Ra) values. Median contact angle values ranged from 51.6° to 114°. Ra values ranged from 0.008 µm to 2.917 µm. Air-polishing as well as other polishing procedures increased surface roughness values in all materials except zirconium dioxide. Polyetheretherketone displayed greatest change in contact angle values after air-polishing treatment.

In-vitro-Testung der Thrombozytenaggregation an zahnärztlich verwendeten kollagenen Hämostyptika

AIM The aim of the present study was to evaluate the adhesion of thrombocytes to different collagenous hemostyptics in a new blood flow chamber. MATERIAL AND METHODS Three hemostyptics were tested: (1) Resorba (RE, native equine collagen, Resorba Wundversorgung GmbH, Nürnberg, Germany), (2) Hemocol (HE, native porcine collagen, Medical Biomaterial Products GmbH, Neustadt-Gleve, Germany), and (3) an experimental sponge (ES, chemically cross-linked porcine collagen, Geistlich Biomaterials, Wolhusen, Switzerland). Ten specimens of each sponge were exposed to a laminar 40 ml/h anticoagulated blood flow and adhering thrombocytes were examined using a confocal laser scanning microscope (CLSM). Pure collagen (Kollagen S, Roche) served as positive control and fetal calf serum (FKS, Roche) as negative control. Examination time was set at 0, 60, 120, and 180 s. Furthermore, pH measurements of defined sponge volumes were evaluated after incubation with NaCl and human blood serum after 3, 30, and 60 min. RESULTS All specimens showed a comparable amount of fluorescence units on the surface over time which was statistically not significantly different from the positive control (p>0.05, ANOVA). Nevertheless, acidity of all specimens could be observed after incubation with NaCl and in cases of HE and ES after incubation with human blood serum. CONCLUSION Within the limits of the present in-vitro study it was concluded that (1) all hemostyptics examined showed similar results in thrombocyte adhesion; (2) chemical cross-linking of collagen does not affect the thrombogenicity of the tested collagen; (3) however, the acidity might have a negative effect on thrombus formation in vivo.

Scuba Diving After Extensive Head and Neck Reconstructive Surgery: Is it Possible?

In the case described herein, the CT scans revealed tooth fragments embedded in the tongue. The parasagittal cuts revealed the anterior–posterior and slightly cranial–caudal direction of the fragments and the parasagital cuts revealed that the fragments followed a left to right direction. These findings allowed the precise localization of the foreign bodies and facilitated their removal from the lacerations in the tongue with the aid of a long hemostatic clamp without the need for incisions.