Matthias Fenner

Panoramic radiograph, computed tomography or magnetic resonance imaging. Which imaging technique should be preferred in bisphosphonate-associated osteonecrosis of the jaw? A prospective clinical study

It was the aim of the present study to find out which radiological imaging techniques allow assessing the extent of bisphosphonate-associated osteonecrosis of the jaw (BONJ) in an adequate way. Twenty-four patients suffering from BONJ were included in the study. Before surgery, each patient was examined with panoramic radiograph, contrast-enhanced magnetic resonance imaging (MRI) and non-enhanced computed tomography. The detectability of BONJ was assessed for the three imaging techniques. The extent of the jaw region affected by BONJ was determined in MRI and CT scans and compared to the intra-operative situation. The detectability of BONJ lesions was 54% for panoramic radiographs, 92% for MRI scans and 96% for computed tomography (CT) scans. The intra-operatively assessed extent of BONJ correlated significantly with the measurements on CT scans (p = 0.0004) but did not correlate significantly with the measurements in MRI scans (p = 0.241). The intra-operatively measured extent of BONJ differed significantly from the CT measurements (p = 0.00003) but not from the MRI data (p = 0.137). Although MRI as well as CT have a high detectability for BONJ lesions that exceeds that of panoramic radiographs by far, both techniques show problems with the exact assessment of the extent of BONJ lesions in the individual patients. Therefore, the relevance of MRI and CT for the preoperative assessment of the extent of BONJ lesions is limited. Future research should focus on the identification of imaging techniques that allow assessing the extent of BONJ lesions with a higher accuracy.

Validation of histologic changes induced by external irradiation in mandibular bone. An experimental animal model

The present experimental study sought to determine the effect of high-dose irradiation on the rat mandible in order to establish an experimental model of radiogenic bone damage. The left mandibles of 20 adult Wistar rats were irradiated (single fraction 1500cGy, total dose 60Gy) by means of a hypofractionated stereotactic radiotherapy (hfSRT) over a period of 6 weeks. Follow-up was 6 weeks (group 1, n=10) and 12 weeks (group 2, n=10). The contralateral mandibles as well as 5 non-irradiated animals served as controls. Primary endpoints were fibrosis, loss of cell count, decreased immunohistochemical labelling for bone morphogenetic protein-2 (BMP-2) and osteocalcin as well as increased expression of transforming growth factor (TGF-beta). Cell loss, progressive fibrosis, and focal necrosis were detected in all irradiated sites. Quantitative measurement revealed 32.0+/-8.7% and 37.3+/-9.5% empty osteocyte lacunae for groups 1 and 2 resp., compared to 16.3+/-4.7% and 18.9+/-4.9% on the contralateral side and 7.9+/-1.7% for unirradiated controls (Mann-Whitney U test; p<.01). BMP-2 and osteocalcin labelling showed a marked decrease in irradiated and contralateral sides while TGF-beta was expressed strongly in irradiated sites only (for all p<.05). External hypofractionated irradiation with a total dose of 60Gy is feasible in rats and yields all histologic changes attributed to osteoradionecrosis (ORN) after a follow-up of 6 weeks. The irradiation protocol is suitable for an assessment of regenerative options in severe radiogenic bone damage. As a split mouth design entails major inaccuracies healthy animals have to be used as controls.

Is there a need for autogenous blood donation in orthognathic surgery

Background: The present study sought to determine the frequency of blood transfusion and to evaluate the need for autogenous blood donations in patients undergoing bimaxillary orthognathic surgery. Methods: According to an inclusion and exclusion protocol, 65 patients were selected for further analysis. Twenty-six patients donated a total of 45 units of autogenous blood; the remaining 39 patients did not. Medical records were reviewed retrospectively. Results: Donors tended to have lower preoperative, intraoperative, and postoperative hemoglobin values, as well as lower hematocrit and leukocyte counts. Only the difference in mean preoperative leukocyte count, however, was statistically significant (donor: 6500/&mgr;l versus nondonor: 7400/&mgr;l; p = 0.021). The rate of transfusion was 2.5 percent for nondonors and 13 percent for donors of autogenous blood. Six donors had to be transfused a total of 8 units of autogenous blood, whereas only one of 39 nondonors received an allogenic blood transfusion. This difference turned out to be significant according to Fishers exact test (p = 0.013). None of the donors received allogenic blood transfusion. Conclusions: In the authors’ analysis, preoperative autogenous blood donation appears to be effective in reducing exposure to allogenic blood. Donors of autogenous blood, however, were transfused significantly more often than nondonors were. Neither intraoperative blood loss nor hematological values justify a preoperative donation of autogenous blood on a regular basis.

Influence of residual alveolar bone height on osseointegration of implants in the maxilla: a pilot study.

AIMS/BACKGROUND For sinus floor augmentation and simultaneous implant placement, a minimum of 5 mm of residual bone height has been recommended empirically. This study was designed to test this assumption in an experimental animal trial. MATERIAL AND METHODS In eight mini pigs, three premolars and two molars were removed on one side of the maxilla. Three months later, the animals were assigned to four groups of two animals each. A cavity was created at the base of the alveolar process so that the residual bone height was reduced to 2, 4, 6 and 8 mm, respectively. Six implants were installed and an inlay augmentation procedure was carried out using a particulated iliac bone graft. Implants were loaded with fixed provisional restorations after a healing period of 6 months. The animals were sacrificed after 6 months of functional loading. Histologic specimens were prepared and histomorphometric analysis was performed [bone-to-implant contact (BIC) ratio, interthread bone area, peri-implant bone area, crestal bone resorption (CBR)]. RESULTS Two implants were lost during follow-up and fibrous encapsulation was detected in one additional implant. All failures occurred in one animal with a residual alveolar height of 2 mm. On the buccal aspect, BIC turned out to be significantly higher for 6 mm when compared with 2/4 mm (75.8 +/- 26.1 vs. 58 +/- 23.2/53.9 +/- 22.8; P<0.05), while on the palatal aspect, BIC was significantly higher for 6/8 mm when compared with 2/4 mm (80 +/- 17.8/78.9 +/- 10.3 vs. 55.8 +/- 26.5/55.6 +/- 21.3; P<0.05). For an alveolar height of 8 mm, CBR tended to be significantly lower than for bone heights of 2/4 mm (3.8 +/- 2.3 vs. 5.3 +/- 2.6/5.8 +/- 3.9; P<0.05). Correlation analysis revealed a significant association of BIC and interthread bone area as well as a negative association to CBR on the palatal aspect. CONCLUSION The results of the present study show that the combination of maxillary inlay grafting and simultaneous implant placement does not hinder osseous integration even though the alveolar crest has been reduced to a residual height of 4 mm and below. However, according to histomorphometry, the highest predictability is gained in sites with residual bone heights of 6 and 8 mm.

Vertical and Sagittal Growth in Patients with Unilateral and Bilateral Cleft Lip and Palate—A Retrospective Cephalometric Evaluation:

Objective: To investigate whether the craniofacial vertical and sagittal jaw relationship in patients with cleft lip and palate (CLP) differed from that of age-matched noncleft controls, before and after the pubertal growth spurt. Design: Retrospective observational study. Patients: The study group comprised 126 patients with CLP, subdivided according to gender and cleft type, and the control group comprised 53 age-matched skeletal class I patients. Methods: Angular and linear measurements were taken from prepubertal and postpubertal lateral cephalograms of all patients. Results: In patients with cleft lip and palate, the maxillary retrognathism became more remarkable with increasing age; whereas, the retrognathic position of the mandible became less pronounced as compared with controls. Reduced posterior midfacial height, a common prepubertal finding in patients with cleft lip and palate, was significant in postpubertal girls and young women with unilateral cleft lip and palate (p  =  .002). The total anterior facial height in male patients with bilateral cleft lip and palate was larger than in control patients (p  =  .002) after the pubertal growth spurt due to an increased anterior midfacial height. In male patients with unilateral cleft lip and palate, this finding was due to an increased anterior lower facial height (p < .001). Conclusions: Patients with cleft lip and palate treated according to a standardized treatment concept had adequate craniofacial jaw relationships after puberty. Despite a measured skeletal class I in both male and female patients with cleft lip and palate regardless of cleft type, there was a slight tendency toward a skeletal class III. Findings were similar for all groups of cleft lip and palate patients irrespective of the type of orthodontic treatment performed.

Influence of residual alveolar bone height on implant stability in the maxilla: an experimental animal study

AIMS/BACKGROUND Empirically, for implant placement associated with sinus floor augmentation, a minimum of five mm of residual crestal bone height has been recommended in order to achieve sufficient initial implant stability. It has been the aim of the study to test this assumption in an experimental animal trial. MATERIAL AND METHODS In eight mini pigs, three premolars and two molars were removed on one side of the maxilla. Three months later the animals were assigned to four groups of two animals each. A cavity was created at the base of the alveolar process so that the residual bone height was reduced to 2, 4, 6 and 8mm, respectively. The coronal part of the alveolar crest remained unchanged. An inlay augmentation procedure was carried out using a particulated autogenous bone graft from the iliac crest, and six implants (Xive, diameter 3.8mm, length 13mm) were placed. Implant stability was assessed by resonance frequency analysis at the time of implant placement (T0), after 6 months of unloaded healing (T1) and after 6 months of functional loading (T2). RESULTS During follow-up, two implants were lost in sites with a residual alveolar bone height of 2mm. At the time of implant placement, resonance frequencies were 6754.4 +/- 268, 6500.3 +/- 281.5, 6890.3 +/- 255.4 and 7877.9 +/- 233.7 Hz for residual bone heights of 2, 4, 6 and 8mm, respectively. At stage-two surgery and after 6 months of functional loading, resonance frequencies were 6431.7 +/- 290.8, 6351.8 +/- 437.6, 6213.4 +/- 376.2 and 6826.8 +/- 458.9 Hz vs. 6171 +/- 437.4, 6047 +/- 572.4, 6156.7 +/- 272.6 and 6412.8 +/- 283.5 Hz. Statistical analysis revealed an association of residual alveolar height and implant stability at T0 and T1 only (P<0.01), while bone height was not found to influence implant survival. CONCLUSION The results of the present trial demonstrate an association of alveolar bone height and implant stability at the time of implant placement and stage-two surgery. Yet the assumption that 5mm of residual crestal bone height is a relevant threshold for simultaneous implant placement and sinus floor augmentation is not supported from an experimental point of view.

Which region of the median palate is a suitable location of temporary orthodontic anchorage devices? A histomorphometric study on human cadavers aged 15–20 years

INTRODUCTION Endosseus implants can provide a reliable anchorage during orthodontic treatment. The midpalatal structures around the sutura palatina mediana (SPM) are of special interest due to increasing placement of orthodontic implants in this area. Knowledge about the osseous conditions at this site is necessary to predict the expected degree of implant osseointegration. METHODS The upper jaws of 10 human cadavers, aged 15-20 years, were decalcified, and cross-sectional specimens were obtained from four anterior-to-posterior palatal regions for histomorphometric analysis. The analyses focused on the amount of bone and the width of the SPM to determine the anatomical requirements for reliable insertion of palatal implants. RESULTS Bone density [bone-volume (BV)/ tissue-volume (TV)] in all measured areas was 40-60%. The maximum density was measured at the level of the first premolars (54.9+/-5.9%) and the least values (44.2+/-9.6%) were measured at the level of the interconnecting line of the canines. The mean width of the SPM varies from 1.2 to 0.3 mm in different sections of the palate. In the median sagittal plane, the mean values of bone height to nasal cavity reached >5 mm as far as the level distal of the second premolars. Bone height 2 mm paramedian to the SPM decreased consistently from anterior (4.3+/-0.9 mm) to posterior (2.5+/-0.8 mm). CONCLUSIONS Our results indicate that the amount and quality of bone along the anterior palatal midline in 15-to-20-year olds is sufficient for orthodontic implantation. Even implantation posterior to the recommended first premolar level, at which orthodontic implants are most often placed, may be suitable. There are some limitations, however, due to small number of samples and variations of anatomical structures.

Prognostic impact of blood transfusion in patients undergoing primary surgery and free‐flap reconstruction for oral squamous cell carcinoma

The objective of this study was to assess the impact of perioperative transfusion on the prognosis of patients who underwent complete (R0) resection of oral squamous cell carcinoma and reconstruction by microvascular flaps.

Prosthodontic treatment of a patient with bisphosphonate-induced osteonecrosis of the jaw using a removable dental prosthesis with a heat-polymerized resilient liner: a clinical report.

Bisphosphonate-induced osteonecrosis of the jaws (BONJ) is reported frequently in patients receiving oral or intravenous bisphosphonates. To minimize potential complications, dental treatment must be performed with care. There are invasive and noninvasive treatment options for patients with active BONJ or a history of this complication. This clinical report describes the prosthodontic treatment of a patient who developed BONJ after receiving intravenous bisphosphonates (pamidronate). Because of the recurrent incidence of BONJ, noninvasive prosthetic therapy with telescopic overdentures and a heat-polymerized resilient liner was provided. After 2 years, there were no biological or technical complications.

Blood transfusion in bimaxillary orthognathic operations: Need for testing of type and screen

We prospectively evaluated the incidence of blood transfusion in 105 consecutively treated patients (45 men and 60 women) having bimaxillary orthognathic operations, to find out whether type and screen testing are adequate in clinical practice. All patients had Le Fort I osteotomy combined with bilateral sagittal split osteotomy of the ramus. The preoperative routine was restricted to type and screen testing and verification of ABO/Rhesus (Rh) status. Autologous blood donation or routine cross-matching of allogeneic units of blood was not done. Intraoperative haemoglobin concentrations and the need for blood transfusion in patients having bimaxillary osteotomies were recorded in a prospective database. The mean duration of operation was 196 min (range 115-325). The median length of hospital stay was 8 days (range 4-16). The mean (SD) reduction in haemoglobin during operation was 34 (16)g/L in men and 32 (10)g/L in women (p=0.32). No patients had an allogeneic blood transfusion. We found that type and screen testing and verification of ABO/Rh status seems to be an adequate precaution to manage blood loss. As reflected by the low rate of transfusion in the present study, severe haemorrhage that requires transfusion of allogeneic blood has become the exception rather than the rule in bimaxillary orthognathic operations.