Michael Dau

Surgical evaluation of panoramic radiography and cone beam computed tomography for therapy planning of bisphosphonate-related osteonecrosis of the jaws

OBJECTIVES The purpose of this retrospective study was to compare the clinical significance of panoramic radiography (orthopantomography [OPTG]) and cone beam computed tomography (CBCT) for therapy planning of bisphosphonate-related osteonecrosis of the jaw (BRONJ) by surgeons. STUDY DESIGN Using standardized questionnaire, eight maxillofacial surgeons evaluated intraoral photographs of the clinical situation of 14 patients with BRONJ as well as the corresponding radiographic images (OPTG, CBCT). The presence of five typical BRONJ signs (bone-remodeling, periosteal reaction, osteosclerosis, sequestra, and continuity of cortical bone) was evaluated with OPTG and CBCT. The influence of radiologic information on therapy decision was examined as well. RESULTS On the basis of the information from intraoral photographs only, seven of the eight surgeons indicated that an additional radiographic examination was necessary for further therapy planning. For evaluation of the five radiographic BRONJ signs, CBCT provided significantly better values compared with OPTG (all P < .05). A before-and-after comparison showed that four of the eight surgeons changed their therapy concept after having three-dimensional CBCT information. The majority (6 of 8) of the surgeons considered that an additional CBCT was required for therapy planning, even after having studied the clinical photographs and OPTG images. CONCLUSION These data demonstrate a significant advantage of CBCT over OPTG for surgeons with regard to therapeutic planning for BRONJ.

Association between glycemia, serum lipoproteins, and the risk of oral leukoplakia: the population-based Study of Health in Pomerania (SHIP).

OBJECTIVE Oral leukoplakia is an oral lesion with a premalignant character. Besides smoking and alcohol, diabetes could be a risk factor. The aim is to search for such an association. RESEARCH DESIGN AND METHODS Subjects with leukoplakia (N = 123) from the population-based Study of Health in Pomerania (SHIP) were matched 1:2 for age and sex with unaffected control subjects. Behavioral and lifestyle factors were assessed by a questionnaire. Lipoprotein concentrations, glycemia, and inflammation parameters were determined. RESULTS Subjects with oral leukoplakia showed higher levels of diabetes-related metabolites, a higher LDL/HDL cholesterol ratio (P = 0.004), and higher A1C (P = 0.002), and they were more frequently smokers (P < 0.001). Assessed by conditional logistic regression, the probability of leukoplakia increases with current smoking (odds ratio 2.20 [95% CI 1.16–4.17]) and higher levels of A1C (1.51 [95% CI 1.08–2.12]), revealing interaction between both factors (P = 0.012). CONCLUSIONS Diabetes is associated with the risk of oral leukoplakia, which is exaggerated by smoking. The risk is positively correlated with A1C concentrations.

The Association between Glycemia, Serum Lipoproteins and the Risk of Oral Leukoplakia: The Population-Based Study SHIP

OBJECTIVE Oral leukoplakia is an oral lesion with a premalignant character. Besides smoking and alcohol, diabetes could be a risk factor. The aim is to search for such an association. RESEARCH DESIGN AND METHODS Subjects with leukoplakia (N = 123) from the population-based Study of Health in Pomerania (SHIP) were matched 1:2 for age and sex with unaffected control subjects. Behavioral and lifestyle factors were assessed by a questionnaire. Lipoprotein concentrations, glycemia, and inflammation parameters were determined. RESULTS Subjects with oral leukoplakia showed higher levels of diabetes-related metabolites, a higher LDL/HDL cholesterol ratio (P = 0.004), and higher A1C (P = 0.002), and they were more frequently smokers (P < 0.001). Assessed by conditional logistic regression, the probability of leukoplakia increases with current smoking (odds ratio 2.20 [95% CI 1.16–4.17]) and higher levels of A1C (1.51 [95% CI 1.08–2.12]), revealing interaction between both factors (P = 0.012). CONCLUSIONS Diabetes is associated with the risk of oral leukoplakia, which is exaggerated by smoking. The risk is positively correlated with A1C concentrations.

Bone formation in mono cortical mandibular critical size defects after augmentation with two synthetic nanostructured and one xenogenous hydroxyapatite bone substitute – in vivo animal study

OBJECTIVES Healing characteristics as well as level of tissue integration and degradation of two different nanostructured hydroxyapatite bone substitute materials (BSM) in comparison with a deproteinized hydroxyapatite bovine BSM were evaluated in an in vivo animal experiment. MATERIAL AND METHODS In the posterior mandible of 18 minipigs, bilateral mono cortical critical size bone defects were created. Randomized augmentation procedures with NanoBone(®) (NHA1), Ostim(®) (NHA2) or Bio-Oss(®) (DBBM) were conducted (each material n = 12). Samples were analyzed after five (each material n = 6) and 8 months (each material n = 6). Defect healing, formation of soft tissue and bone as well as the amount of remaining respective BSM were quantified both macro- and microscopically. RESULTS For NHA2, the residual bone defect after 5 weeks was significantly less compared to NHA1 or DBBM. There was no difference in residual BSM between NHA1 and DBBM, but the amount in NHA2 was significantly lower. NHA2 also showed the least amount of soft tissue and the highest amount of new bone after 5 weeks. Eight months after implantation, no significant differences in the amount of residual bone defects, in soft tissue or in bone formation were detected between the groups. Again, NHA2 showed significant less residual material than NHA1 and DBBM. DISCUSSION We observed non-significant differences in the biological hard tissue response of NHA1 and DBBM. The water-soluble NHA2 initially induced an increased amount of new bone but was highly compressed which may have a negative effect in less stable augmentations of the jaw.

Hydrogel-embedded nanocrystalline hydroxyapatite granules (elastic blocks) based on a cross-linked polyvinylpyrrolidone as bone grafting substitute in a rat tibia model

Purpose The aim of this study was to examine the in vivo characteristics and levels of integration and degradation of a ready-to-use bone grafting block with elastic properties (elastic block) for the use in surgery. Materials and methods Thirty-six male Wistar rats underwent surgical creation of a well-defined bone defect in the tibia. All created defects – one per animal – were filled with an unsintered nanocrystalline hydroxyapatite embedded either with a non-cross-linked hydrogel carrier (CONT, n=18) or a cross-linked hydrogel carrier (elastic block [EB], n=18) based on polyvinylpyrrolidone (PVP) and silica sol, respectively. The animals were killed after 12 (n=12), 21 (n=12) and 63 days (n=12). The bone formation and defect healing were quantified by histomorphometric measurements made in paraffin sections. Additionally, immunohistochemical (tartrate-resistant acid phosphatase [TRAP] and alkaline phosphatase [aP]), antibody-based examinations (CD68) and energy-dispersive x-ray scattering measurements of silica atom concentration were carried out. Results A larger remaining bone defect area overall was observed in EB after 12 days and 21 days. After 63 days, similar areas of remaining bone defects were found. The amount of the remaining carrier material in EB overall was higher at all times. In CONT no residual carrier material was found at 12 days and later. CD68 analyses showed significantly lower level of CD68-positive marked cells after 21 days in CONT, and nonsignificant differences at 12 and 63 days, respectively. Additionally, a significantly higher level of aP-positive marked cells was observed in CONT after 12 days. Later on, the levels of aP-positive marked cells were slightly higher in EB (21 and 63 days). Furthermore, no significant differences regarding the level of TRAP-positive marked cells in each group were observed. Conclusion The bone substitute (EB) with the cross-linked PVP-based hydrogel carrier leads at the beginning to a higher amount of remaining carrier material and remaining bone substitute. This delayed degradation is supposed to be the reason for the observed lower level of bone remodeling and is caused by the irradiation changes (cross links) in the structure in PVP.

The ability of hyperspectral imaging to detect perfusion disorders

Blood perfusion as the supply of tissue with blood and therefore oxygen is a key factor in clinical practice. Especially in the field of flap surgery, a reduced perfusion of transplanted skin or operated areas is often cause of various complications. The success of microvascular reconstructions is directly related to the flap perfusion. The intraoperative and postoperative assessment of the anastomoses is of great importance in order to recognize possible complications at an early stage and to revise them in good time. Is the affected tissue located on the face, successful treatment and rapid healing is even more important since aesthetic aspects play a not insignificant role. A poor perfusion is often concealed, since methods are missing for an objective assessment of the perfusion status. A method with increasing importance for clinical practice is given by hyperspectral imaging. We developed a new hyperspectral imaging system that can be used to observe tissue oxygenation and other tissue parameters and present the technical background and the parameter validation.

Hyperspectral imaging for monitoring of perfusion failure upon microvascular anastomosis in the rat hind limb

BACKGROUND/PURPOSE Objective, reliable and easy monitoring of microvascular tissue perfusion is a goal that was achieved for many years with limited success. Therefore, a new non-invasive hyperspectral camera system (TIVITA™) was tested for this purpose in an in vivo animal model. METHODS Evaluation of tissue oxygenation during ischemia and upon reperfusion was performed in left hind limb in a rat model (n=20). Ischemia was induced by clamping and dissection of the superficial femoral artery. Reperfusion of the limb was achieved by microsurgical anastomosis of the dissected artery. Oxygenation parameters of the hind limb were assessed via TIVITA™ before and immediately after clamping and dissection of the artery, 3 and 30min after reperfusion as well as on postoperative days 1 and 2. Thereby, the non-operated hind limb served as control. As clinical parameters, the refill of the anastomosis as well as the progress of the affected leg were assessed. RESULTS In 12 from 20 cases, TIVITA™ recorded a sufficient reperfusion with oxygenation parameters comparable to baseline or control condition. However, in 8 from 20 cases oxygenation was found impaired after reperfusion causing a re-assessment of the microvascular anastomosis. Thereby, technical problems like stenosis or local thrombosis were found in all cases and were surgically treated leading to an increased tissue oxygenation. CONCLUSIONS The TIVITA™ camera system is a valid non-invasive tool to assess tissue perfusion after microvascular anastomosis. As it safely shows problems in oxygenation, it allows the clinician a determined revision of the site in time in order to prevent prolonged ischemia.

Kurze Implantate vs. Augmentation

ZusammenfassungDer Einsatz kurzer Implantate als Alternative zum präimplantologischen Knochenaufbau gewinnt zunehmend an Akzeptanz. Laut derzeitiger Definition handelt es sich hierbei um Implantate mit einer vorgesehenen Länge im Knochen ≤8 mm. Früher wurde unter anderem aufgrund der geringeren Knochen-Implantat-Kontaktfläche und des ungünstigen Kronen-Implantat-Längenverhältnisses bei kurzen Implantaten von geringeren Überlebensraten im Vergleich zu ihren längeren Gegenstücken berichtet. Allerdings scheint die Erfolgsrate moderner kurzer Implantatsysteme mit rauer Oberfläche bei korrekter Indikationsstellung annähernd denen mit Standardlängen zu gleichen. Insbesondere wird von einer Häufung prothetischer Komplikationen bei Kronen-Implantat-Längenverhältnissen >2 berichtet. Im Ergebnis scheinen kurze Implantate in ausgewählten Fällen bei entsprechender Expertise eine gute Alternative zu Augmentation und Insertion längerer Implantate darzustellen, gerade weil dieses Behandlungskonzept schneller und kostengünstiger sowie mit weniger Komplikationen behaftet ist. Allerdings liegen derzeit nur vereinzelte Langzeitstudien mit ausreichenden Fallzahlen und somit nur eine eingeschränkte wissenschaftliche Evidenz vor. Dies lässt eine abschließende Aussage noch nicht zu.

Hyperspectral imaging in perfusion and wound diagnostics – methods and algorithms for the determination of tissue parameters

Abstract Blood perfusion is the supply of tissue with blood, and oxygen is a key factor in the field of minor and major wound healing. Reduced perfusion of a wound bed or transplant often causes various complications. Reliable methods for an objective evaluation of perfusion status are still lacking, and insufficient perfusion may remain undiscovered, resulting in chronic processes and failing transplants. Hyperspectral imaging (HSI) represents a novel method with increasing importance for clinical practice. Therefore, methods, software and algorithms for a new HSI system are presented which can be used to observe tissue oxygenation and other parameters that are of importance in supervising healing processes. This could offer an improved insight into wound perfusion allowing timely intervention.

Kurze Implantate vs. Augmentation: Update

ZusammenfassungDer Einsatz kurzer Implantate als Alternative zum präimplantologischen Knochenaufbau gewinnt zunehmend an Akzeptanz. Laut derzeitiger Definition handelt es sich hierbei um Implantate mit einer vorgesehenen Länge im Knochen ≤8 mm. Früher wurde unter anderem aufgrund der geringeren Knochen-Implantat-Kontaktfläche und des ungünstigen Kronen-Implantat-Längenverhältnisses bei kurzen Implantaten von geringeren Überlebensraten im Vergleich zu ihren längeren Gegenstücken berichtet. Allerdings scheint die Erfolgsrate moderner kurzer Implantatsysteme mit rauer Oberfläche bei korrekter Indikationsstellung annähernd denen mit Standardlängen zu gleichen. Insbesondere wird von einer Häufung prothetischer Komplikationen bei Kronen-Implantat-Längenverhältnissen >2 berichtet. Im Ergebnis scheinen kurze Implantate in ausgewählten Fällen bei entsprechender Expertise eine gute Alternative zu Augmentation und Insertion längerer Implantate darzustellen, gerade weil dieses Behandlungskonzept schneller und kostengünstiger sowie mit weniger Komplikationen behaftet ist. Allerdings liegen derzeit nur vereinzelte Langzeitstudien mit ausreichenden Fallzahlen und somit nur eine eingeschränkte wissenschaftliche Evidenz vor. Dies lässt eine abschließende Aussage noch nicht zu.