Primary human osteoblasts in response to 25-hydroxyvitamin D3, 1,25-dihydroxyvitamin D3and 24R,25-dihydroxyvitamin D3

The most biologically active metabolite 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) has well known direct effects on osteoblast growth and differentiation in vitro. The precursor 25-hydroxyvitamin D3 (25(OH)D3) can affect osteoblast function via conversion to 1,25(OH)2D3, however, it is largely unknown whether 25(OH)D3 can affect primary osteoblast function on its own. Furthermore, 25(OH)D3 is not only converted to 1,25(OH)2D3, but also to 24R,25-dihydroxyvitamin D3 (24R,25(OH)2D3) which may have bioactivity as well. Therefore we used a primary human osteoblast model to examine whether 25(OH)D3 itself can affect osteoblast function using CYP27B1 silencing and to investigate whether 24R,25(OH)2D3 can affect osteoblast function. We showed that primary human osteoblasts responded to both 25(OH)D3 and 1,25(OH)2D3 by reducing their proliferation and enhancing their differentiation by the increase of alkaline phosphatase, osteocalcin and osteopontin expression. Osteoblasts expressed CYP27B1 and CYP24 and synthesized 1,25(OH)2D3 and 24R,25(OH)2D3 dose-dependently. Silencing of CYP27B1 resulted in a decline of 1,25(OH)2D3 synthesis, but we observed no significant differences in mRNA levels of differentiation markers in CYP27B1-silenced cells compared to control cells after treatment with 25(OH)D3. We demonstrated that 24R,25(OH)2D3 increased mRNA levels of alkaline phosphatase, osteocalcin and osteopontin. In addition, 24R,25(OH)2D3 strongly increased CYP24 mRNA. In conclusion, the vitamin D metabolites 25(OH)D3, 1,25(OH)2D3 and 24R,25(OH)2D3 can affect osteoblast differentiation directly or indirectly. We showed that primary human osteoblasts not only respond to 1,25(OH)2D3, but also to 24R,25(OH)2D3 by enhancing osteoblast differentiation. This suggests that 25(OH)D3 can affect osteoblast differentiation via conversion to the active metabolite 1,25(OH)2D3, but also via conversion to 24R,25(OH)2D3. Whether 25(OH)D3 has direct actions on osteoblast function needs further investigation

Immediate dental implant placement and restoration in the edentulous mandible in head and neck cancer patients: a systematic review and meta-analysis

PURPOSE OF REVIEW: Oral rehabilitation with dental implants in head and neck cancer (HNC) patients is challenging. After tooth removal prior to radiotherapy, immediate placement of dental implants during panendoscopy or surgery is thought to reduce the oral rehabilitation time improving patients' quality of life. RECENT FINDINGS: There is lack of consensus on the timing of dental implant placement and loading protocols. The aim of this study was to perform a systematic review of the literature regarding the performance and survival rate of immediately inserted dental implants placed prior to radiotherapy. Of 1003 articles, 10 were finally included comparing immediate vs. delayed placement of implants and comparing the effect of radiotherapy on immediately placed implants. Meta-analysis demonstrated a slightly higher survival of immediately placed implants compared with postponed placed implants [risk ratio: 0.92, 95% confidence interval (95% CI): 0.48-1.78, P = 0.81, I2 = 0%]. The other meta-analysis comparing radiotherapy vs. nonradiotherapy showed a clearly better survival of immediately placed implants not having received radiotherapy (risk ratio: 5.02, 95% CI: 0.92-27.38, P = 0.10, I2  = 56%). SUMMARY: Guidelines are recommended for immediate dental implant placement in the edentulous mandible in HNC patients prior to radiotherapy to allow homogeneity regarding the treatment protocols and thus comparison of treatment outcomes

Dental floss as a possible risk for the development of peri-implant disease: an observational study of 10 cases

AIM To report on a possible relationship between the use of dental floss or superfloss and the development of peri-implantitis. MATERIALS AND METHODS Ten patients with progressive peri-implantitis with an intensive oral hygiene protocol, which consisted of extensive professional supra- and submucosal cleaning, and not responding to this therapy were scheduled for examination. Plaque and bleeding indices and probing depth measurements were assessed, and radiographic examination was performed every two years. RESULTS In all ten cases, remnants of dental floss were found around the neck and coronal part of a dental implant. After careful removal of these floss remnants and implant cleansing, a significant improvement in the peri-implant conditions in nine of ten cases was noted. In one case, peri-implant probing depth decreased substantially. However, bleeding on probing was still present. In vitro testing yielded that the application of various types of dental floss on the exposed rough implant surfaces may easily lead to tearing of floss fibers. This may result in the deposition of floss remnants on rough implant surfaces, which, in turn, may lead to the development of plaque-related peri-implant inflammation and, subsequently, bone loss. CONCLUSION In case of exposed rough surfaces of the dental implant, the peri-implant conditions may be jeopardized by the application of dental floss, and hence, the utilization of interproximal brushes or toothpicks may be preferred for daily home care practices

Altered nasal airflow: an unusual complication following implant surgery in the anterior maxilla

Dental implants have been in routine clinical use for over three decades and are a predictable treatment modality. However, as with all other aspects of dentistry, complications occur. A 50-year-old female patient with complaints of a long ongoing unpleasant altered nasal airflow presented herself at the VU University Medical Center Amsterdam. Visual inspection of the right nasal cavity revealed that the apical part of a dental implant placed in the upper right first incisor region had perforated the nasal floor and was partially protruding into the nasal cavity. Subsequent treatment consisted of a transnasal resection of the apical part of the dental implant to the level of the nasal floor. After a 12-month follow-up period, the patient reported having no altered nasal airflow. In conclusion, dental implants protruding into the nasal cavity can cause an alteration to the airflow. Furthermore, a partial removal of the apical part of the dental implant is a viable method of treating dental implants that extend into the nasal cavity

Tissue level changes after maxillary sinus floor elevation with three types of calcium phosphate ceramics: A radiological study with a 5‐year follow‐up

This study evaluates the radiological changes in tissue height after maxillary sinus floor elevation (MSFE) using three types of calcium phosphate ceramics over a period of up to 5 years after dental implant placement. In 163 patients, MSFE was performed. Three groups of patients were distinguished and treated based on the type of calcium phosphate ceramic used and radiologically evaluated: 40 patients with β‐tricalcium phosphate (β‐TCP), 76 patients with biphasic calcium phosphate (BCP) 20% hydroxyapatite (HA)‐80% β‐TCP, and 47 patients with BCP 60% HA‐ 40% β‐TCP. Radiological measurements were performed on panoramic radiographs at several time points up to 5 years after dental implant placement. After MSFE, a slow decrease in tissue height measured over time was seen in all three study groups. Resorption of the grafted bone substitutes was more prominent in β‐TCP than in BCP ceramics with an HA component (60/40 and 20/80). Loss of tissue height after 5 years was lowest in BCP 60/40 and highest in β‐TCP. This radiological study shows a predictable and comparable behavior of the slow decrease in tissue height over time for all three types of calcium phosphate ceramics used in MSFE. The fraction of HA in calcium phosphate ceramics and dental implant loading seems to be beneficial for tissue height maintenance after MSFE

Effect of smoking on MUC1 expression in oral epithelial dysplasia, oral cancer, and irradiated oral epithelium

Objectives: The aim of this study was to assess the MUC1 expression in the oral epithelium of normal, oral epithelial dysplasia (OED), oral squamous cell carcinoma (OSCC), and irradiated oral epithelium (IROE) and its association with smoking habits in non-smokers and smokers. Design: Oral mucosal biopsies from controls, OED, OSCC, and IROE groups were obtained and categorized based on the smoking history as non-smokers, smoker I (25 pack-years), and smoker II (>25 pack-years). Immunohistochemical staining of MUC1 using human milk fat globule 1 (HMFG 1) antibody was performed, and the MUC1 score was calculated. The relation between MUC1 expression and clinicopathological findings was examined. Results: MUC1 staining of superficial oral epithelial cells with mild MUC1 score was detected in all control samples. The MUC1 staining extended from superficial to basal cell layer of oral epithelium with the increase in MUC1 score from moderate to strong in OED, OSCC, and IROE, and the difference was significant (p < 0.004, p < 0.002 and p < 0.004, respectively) compared to controls. A positive association between smoking and MUC1 score was observed within groups (p < 0.05). Conclusion: The depolarization of MUC1 protein expression is associated with smoking habits in OED and OSCC. In the IROE, the radiation causes subcellular and molecular changes, observed as altered MUC1 expression and accelerated by smoking, furthermore, complicating the oral mucosal adaptation and progress to radiation-induced lesions as a delayed effect

Molecular Quantity Variations in Human-Mandibular-Bone Osteoid

Osteoid is a layer of new-formed bone that is deposited on the bone border during the process of new bone formation. This deposition process is crucial for bone tissue, and flaws in it can lead to bone diseases. Certain bone diseases, i.e. medication related osteonecrosis, are overexpressed in mandibular bone. Because mandibular bone presents different properties than other bone types, the data concerning osteoid formation in other bones are inapplicable for human-mandibular bone. Previously, the molecular distribution of other bone types has been presented using Fourier-transform infrared (FTIR) spectroscopy. However, the spatial distribution of molecular components of healthy-human-mandibular-bone osteoid in relation to histologic landmarks has not been previously presented and needs to be studied in order to understand diseases that occur human-mandibular bone. This study presents for the first time the variation in molecular distribution inside healthy-human-mandibular-bone osteoid by juxtaposing FTIR data with its corresponding histologic image obtained by autofluorescence imaging of its same bone section. During new bone formation, bone-forming cells produce an osteoid constituted primarily of type I collagen. It was observed that in mandibular bone, the collagen type I increases from the osteoblast line with the distance from the osteoblasts, indicating progressive accumulation of collagen during osteoid formation. Only later inside the collagen matrix, the osteoid starts to mineralize. When the mineralization starts, the collagen accumulation diminishes whereas the collagen maturation still continues. This chemical-apposition process in healthy mandibular bone will be used in future as a reference to understand different pathologic conditions that occur in human-mandibular bone

Oral-Functioning Questionnaires in Patients with Head and Neck Cancer: A Scoping Review

Background: Oral-functioning impairment can negatively affect the quality of life (QoL) of head and neck cancer (HNC) patients after receiving radiotherapy (RT). Assessment of patient-reported oral functioning throughout treatment can improve patient care. This scoping review aims to propose a definition for oral functioning for HNC patients and to map out the available questionnaires measuring patient-reported oral functioning in RT-treated HNC patients. Methods: A literature search in relevant databases was performed. Each questionnaire was scored on the domains validity, reliability, and responsiveness. Furthermore, the items from the questionnaires were analyzed to define the common denominators for oral functioning in HNC patients. Results: Of the 6434 articles assessed, 16 met the inclusion criteria and employed 16 distinct instruments to evaluate QoL. No questionnaire covered all oral-health-related QoL items nor assessed all aspects of validity, reliability, and responsiveness. Chewing, speaking, and swallowing were the common denominators for oral functioning. Conclusions: Based on the included studies, we suggest using the VHNSS 2.0 questionnaire to assess oral functioning in HNC patients. Furthermore, we suggest to more clearly define oral functioning in HNC patients by focusing on masticatory function (chewing and grinding), mouth opening, swallowing, speaking, and salivation

Osteocyte morphology and orientation in relation to strain in the jaw bone

Bone mass is important for dental implant success and is regulated by mechanoresponsive osteocytes. We aimed to investigate the relationship between the levels and orientation of tensile strain and morphology and orientation of osteocytes at different dental implant positions in the maxillary bone. Bone biopsies were retrieved from eight patients who underwent maxillary sinus-floor elevation with β-tricalcium phosphate prior to implant placement. Gap versus free-ending locations were compared using 1) a three-dimensional finite-element model of the maxilla to predict the tensile strain magnitude and direction and 2) histology and histomorphometric analyses. The finite-element model predicted larger, differently directed tensile strains in the gap versus free-ending locations. The mean percentage of mineralised residual native-tissue volume, osteocyte number (mean ± standard deviations: 97 ± 40/region-of-interest), and osteocyte shape (~90% elongated, ~10% round) were similar for both locations. However, the osteocyte surface area was 1.5-times larger in the gap than in the free-ending locations, and the elongated osteocytes in these locations were more cranially caudally oriented. In conclusion, significant differences in the osteocyte surface area and orientation seem to exist locally in the maxillary bone, which may be related to the tensile strain magnitude and orientation. This might reflect local differences in the osteocyte mechanosensitivity and bone quality, suggesting differences in dental implant success based on the location in the maxilla