Vivek Thumbigere-Math

Bisphosphonate-Related Osteonecrosis of the Jaw: Clinical Features, Risk Factors, Management, and Treatment Outcomes of 26 Patients

PURPOSE To report the clinical features, risk factors, management, and treatment outcomes of nitrogen-containing bisphosphonate (n-BIS)-related osteonecrosis of the jaw (BRONJ). PATIENTS AND METHODS Patients with suspected BRONJ were referred to the School of Dentistry for evaluation and treatment. RESULTS A total of 26 patients (9 men and 17 women, mean age 64 years) were diagnosed with BRONJ. Of the 26 patients, 23 had received n-BIS therapy for cancer and 3 for osteoporosis. BRONJ lesions were noted more frequently in the mandible and in the posterior sextants. Of the 26 patients, 16 had developed BRONJ after dentoalveolar procedures, and 10 had developed it spontaneously. The mean interval to development of BRONJ was shorter in the patients with cancer receiving intravenous n-BIS than in the patients with osteoporosis receiving oral n-BIS (37.1 versus 77.7 months, P = .02). Using the American Association of Oral and Maxillofacial Surgeons staging system, 2 patients were diagnosed with stage I lesions, 19 with stage II, and 5 with stage III lesions. The initial management of BRONJ was nonsurgical, with debridement performed at subsequent visits, if needed. The BRONJ lesions healed completely in 4 patients, healed partially in 8, remained stable in 7, and progressed in 7. The spontaneous lesions responded favorably to BRONJ management compared with lesions that developed after dentoalveolar procedures (P = .01). No significant difference was found in response to BRONJ management between patients who had continued or discontinued n-BIS therapy after the BRONJ diagnosis (P = .54). CONCLUSIONS Long-term n-BIS therapy and recent dental procedures are consistent findings in patients with BRONJ. Spontaneous BRONJ lesions respond favorably to current BRONJ treatment strategies.

A retrospective study evaluating frequency and risk factors of osteonecrosis of the jaw in 576 cancer patients receiving intravenous bisphosphonates

ObjectiveTo evaluate the frequency, risk factors, and clinical presentation of bisphosphonate (BP)-related osteonecrosis of the jaw (BRONJ). Study DesignWe performed a retrospective analysis of 576 patients with cancer treated with intravenous pamidronate and/or zoledronate between January, 2003 and December, 2007 at the University of Minnesota Masonic Cancer Center and Park Nicollet Institute. ResultsEighteen of 576 identified patients (3.1%) developed BRONJ including 8 of 190 patients (4.2%) with breast cancer, 6 of 83 patients (7.2%) with multiple myeloma, 2 of 84 patients (2.4%) with prostate cancer, 1 of 76 patients (1.3%) with lung cancer, 1 of 52 patients (1.9%) with renal cell carcinoma, and in none of the 73 patients with other malignancies. Ten patients (59%) developed BRONJ after tooth extraction, whereas 7 (41%) developed it spontaneously (missing data for 1 patient). The mean number of BP infusions (38.1±19.06 infusions vs. 10.5±12.81 infusions; P<0.001) and duration of BP treatment (44.3±24.34 mo vs. 14.6±18.09 mo; P<0.001) were significantly higher in patients with BRONJ compared with patients without BRONJ. Multivariate Cox proportional hazards regression analysis showed that diabetes [hazard ratio (HR)=3.40; 95% confidence interval (CI), 1.14-10.11; P=0.028], hypothyroidism (HR=3.59; 95% CI, 1.31-9.83; P=0.013), smoking (HR=3.44; 95% CI, 1.28-9.26; P=0.015), and higher number of zoledronate infusions (HR=1.07; 95% CI, 1.03-1.11; P=0.001) significantly increased the risk of developing BRONJ. ConclusionsIncreased cumulative doses and long-term BP treatment are the most important risk factors for BRONJ development. Type of BP, diabetes, hypothyroidism, smoking, and prior dental extractions may play a role in BRONJ development.

Periodontal Disease as a Risk Factor for Bisphosphonate-Related Osteonecrosis of the Jaw

BACKGROUND Previous case reports and animal studies suggest that periodontitis is associated with bisphosphonate-related osteonecrosis of the jaw (BRONJ). This case-control study is conducted to evaluate the association between clinical and radiographic measures of periodontal disease and BRONJ. METHODS Twenty-five patients with BRONJ were matched with 48 controls. Trained examiners measured probing depth, clinical attachment level (CAL), and bleeding on probing on all teeth except third molars and gingival and plaque indices on six index teeth. Alveolar bone height was measured from orthopantomograms. Most patients with BRONJ were using antibiotics (48%) or a chlorhexidine mouthrinse (84%) at enrollment. Adjusted comparisons of patients with BRONJ versus controls used multiple linear regression. RESULTS The average number of bisphosphonate (BP) infusions was significantly higher in patients with BRONJ compared with controls (38.4 versus 18.8, P = 0.0001). In unadjusted analyses, patients with BRONJ had more missing teeth (7.8 versus 3.1, P = 0.002) and higher average CAL (2.18 versus 1.56 mm, P = 0.047) and percentage of sites with CAL ≥3 mm (39.0 versus 23.3, P = 0.039) than controls. Also, patients with BRONJ had lower average bone height (as a fraction of tooth length, 0.59 versus 0.62, P = 0.004) and more teeth with bone height less than half of tooth length (20% versus 6%, P = 0.001). These differences remained significant after adjusting for age, sex, smoking, and number of BP infusions. CONCLUSIONS BRONJ patients have fewer teeth, greater CAL, and less alveolar bone support compared with controls after adjusting for number of BP infusions. Group differences in antibiotics and chlorhexidine rinse usage may have masked differences in the other clinical measures.

The effects of periodontal treatment on pregnancy outcomes

BACKGROUND Preterm infants are at greater risk than term infants for physical and developmental disorders. Morbidity and mortality increases as gestational age at delivery decreases. Observational studies indicate an association between poor periodontal health and risk for preterm birth or low birthweight, making periodontitis a potentially modifiable risk factor for prematurity. AIM To identify randomized controlled trials (RCTs) published between January 2011 and July 2012 and discuss all published RCTs testing whether periodontal therapy reduces rates of preterm birth and low birthweight. METHODS Search of databases including PubMed, ISI Web of Science and Cochrane Library. RESULTS The single RCT identified showed no significant effect of periodontal treatment on birth outcomes. DISCUSSION All published trials included non-surgical periodontal therapy; only two included systemic antimicrobials as part of test therapy. The trials varied substantially in terms of sample size, obstetric histories of subjects, study preterm birth rates and the periodontal treatment response. The largest trials--also judged to be high-quality and at low risk of bias--have yielded consistent results, and indicate that treatment does not alter rates of adverse pregnancy outcomes. CONCLUSION Non-surgical periodontal therapy, scaling and root planing, does not improve birth outcomes in pregnant women with periodontitis.

Matrix metalloproteinase-9 expression in alveolar extraction sockets of Zoledronic acid-treated rats.

PURPOSE The use of nitrogen-containing bisphosphonates (n-bis) is associated with necrosis of the jaws, also known as bisphosphonate-related osteonecrosis of the jaws (BRONJ); however, the pathophysiology is unknown. Matrix metalloproteinase-9 (MMP-9) expression is essential for normal bone healing and is also required for angiogenesis. N-bis alters MMP-9 expression in vitro and in vivo; therefore, we hypothesized that n-bis alters MMP-9 expression during oral wound healing after tooth extraction. MATERIALS AND METHODS A total accumulated dose of 2.25 mg/kg (n = 20) of Zoledronic acid (ZA) Zometa or saline (control, n = 20) was administered to Sprague-Dawley male rats. Next, both groups had maxillary molar teeth extracted. Rats were sacrificed at postoperative day 1, 3, 7, or 21. Western blotting or multiplex ELISA was used to evaluate proteins of interest. Real-time polymerase chain reaction was used to assess the relative quantities of target gene mRNA. MMP-9 enzymatic activity was assessed by zymography. RESULTS The ZA group showed a statistically significant reduction in bone mineralization rate 21 days after tooth extraction compared with the control group (Student t test, P = .005). Moreover, ZA-treated animals showed a statistically significant increase in MMP-9-specific mRNA at postoperative days 3 (P = .003), 7 (P < .0001), and 21 (P < .0001) and protein on postoperative days 3 (P = .005) and 7 (P < .0001). MMP-9 enzymatic activity was also increased in ZA-treated rats compared with control animals (Student t test, P = .014). We also evaluated the extraction sockets for the presence of tissue inhibitor of MMP-1 (TIMP1), which is an inhibitor of MMP-9 enzymatic activity. TIMP1-specific mRNA and protein were not significantly altered by ZA treatment at the times tested (P > .05). Receptor of NF-κB ligand (RANKL) is known to regulate the expression of MMP-9; we therefore assessed the RANKL expression in our experimental oral wound-healing model. The ZA-treated animals had significantly increased RANKL mRNA at postoperative days 3 (P = .02) and 21 (P = .004), while the protein expression was significantly increased at postoperative days 1 (P < .0001), 7 (P = .02), and 21 (P = .03) compared with the control group. CONCLUSIONS ZA reduced bone mineralization within tooth extraction sockets, suggesting aberrant bone healing. ZA increases the amount and enzymatic activity of MMP-9, while apparently not altering the amount of TIMP1 within extraction sockets. RANKL is increased in ZA-treated rats, which suggests that increased MMP-9 expression is due, in part, to augmented RANKL expression.

The effects of periodontal treatment on pregnancy outcomes.

BACKGROUND Preterm infants are at greater risk than term infants for physical and developmental disorders. Morbidity and mortality increases as gestational age at delivery decreases. Observational studies indicate an association between poor periodontal health and risk for preterm birth or low birthweight, making periodontitis a potentially modifiable risk factor for prematurity. AIM To identify randomized controlled trials (RCTs) published between January 2011 and July 2012 and discuss all published RCTs testing whether periodontal therapy reduces rates of preterm birth and low birthweight. METHODS Search of databases including PubMed, ISI Web of Science and Cochrane Library. RESULTS The single RCT identified showed no significant effect of periodontal treatment on birth outcomes. DISCUSSION All published trials included non-surgical periodontal therapy; only two included systemic antimicrobials as part of test therapy. The trials varied substantially in terms of sample size, obstetric histories of subjects, study preterm birth rates and the periodontal treatment response. The largest trials - also judged to be high-quality and at low risk of bias - have yielded consistent results, and indicate that treatment does not alter rates of adverse pregnancy outcomes. CONCLUSION Non-surgical periodontal therapy, scaling and root planing, does not improve birth outcomes in pregnant women with periodontitis.

Serum Markers of Bone Turnover and Angiogenesis in Patients With Bisphosphonate-Related Osteonecrosis of the Jaw After Discontinuation of Long-Term Intravenous Bisphosphonate Therapy

PURPOSE To analyze serum markers of bone turnover, angiogenesis, endocrine function, and inflammation in patients with bisphosphonate-related osteonecrosis of the jaw (BRONJ) who discontinued long-term intravenous bisphosphonate (BP) therapy. PATIENTS AND METHODS Serum samples were obtained from 25 BRONJ patients who had discontinued long-term intravenous BP therapy for an average of 11.4 ± 8.7 months and 48 non-BRONJ controls who continued receiving intravenous BP therapy. Samples were analyzed for total alkaline phosphatase, bone-specific alkaline phosphatase, osteocalcin, C-telopeptide, vascular endothelial growth factor, triiodothyronine, thyroxine, thyroid-stimulating hormone, 25-hydroxyvitamin D, and C-reactive protein. RESULTS The mean number of BP infusions was significantly higher in BRONJ patients compared with controls (38.4 ± 26.3 infusions vs 18.8 ± 7.2 infusions, P < .0001); however, the duration of BP therapy was not significantly different between the groups (P = .23). Overall, there were no significant differences in any of the markers between BRONJ patients and controls (all P values ≥ .16). In a subgroup analysis that matched BRONJ patients and controls according to mean age and number of BP infusions (10 BRONJ patients and 48 controls), log10 vascular endothelial growth factor (2.9 ± 0.4 pg/mL vs 2.4 ± 0.4 pg/mL, P < .001) and C-reactive protein (34 ± 26 mg/L vs 13 ± 8 mg/L, P < .01) levels were significantly higher in BRONJ patients compared with controls. Within BRONJ patients, none of the serum markers were correlated with duration of BP discontinuation. CONCLUSIONS Levels of bone turnover and endocrine markers in BRONJ patients who discontinue long-term intravenous BP therapy are similar to those in non-BRONJ controls receiving intravenous BP therapy. However, levels of angiogenesis and inflammation markers are higher in BRONJ patients who discontinue long-term intravenous BP therapy. The prolonged skeletal half-life of BPs may suppress bone turnover markers in BRONJ patients for several years after discontinuation of intravenous BP therapy, suggesting an extended effect on bone homeostasis.

PTH and Vitamin D Repress DMP1 in Cementoblasts

A complex feedback mechanism between parathyroid hormone (PTH), 1,25(OH)2D3 (1,25D), and fibroblast growth factor 23 (FGF-23) maintains mineral homeostasis, in part by regulating calcium and phosphate absorption/reabsorption. Previously, we showed that 1,25D regulates mineral homeostasis by repressing dentin matrix protein 1 (DMP1) via the vitamin D receptor pathway. Similar to 1,25D, PTH may modulate DMP1, but the underlying mechanism remains unknown. Immortalized murine cementoblasts (OCCM.30), similar to osteoblasts and known to express DMP1, were treated with PTH (1–34). Real-time quantitative polymerase chain reaction (PCR) and Western blot revealed that PTH decreased DMP1 gene transcription (85%) and protein expression (30%), respectively. PTH mediated the downregulation of DMP1 via the cAMP/protein kinase A (PKA) pathway. Immunohistochemistry confirmed the decreased localization of DMP1 in vivo in cellular cementum and alveolar bone of mice treated with a single dose (50 µg/kg) of PTH (1–34). RNA-seq was employed to further identify patterns of gene expression shared by PTH and 1,25D in regulating DMP1, as well as other factors involved in mineral homeostasis. PTH and 1,25D mutually upregulated 36 genes and mutually downregulated 27 genes by ≥2-fold expression (P ≤ 0.05). Many identified genes were linked with the regulation of bone/tooth homeostasis, cell growth and differentiation, calcium signaling, and DMP1 transcription. Validation of RNA-seq results via PCR array confirmed a similar gene expression pattern in response to PTH and 1,25D treatment. Collectively, these results suggest that PTH and 1,25D share complementary effects in maintaining mineral homeostasis by mutual regulation of genes/proteins associated with calcium and phosphate metabolism while also exerting distinct roles on factors modulating mineral metabolism. Furthermore, PTH may modulate phosphate homeostasis by downregulating DMP1 expression via the cAMP/PKA pathway. Targeting genes/proteins mutually governed by PTH and 1,25D may be a viable approach for designing new therapies for preserving mineralized tissue health.

Salivary proteomics in bisphosphonate-related osteonecrosis of the jaw

OBJECTIVE The objective of this study was to identify differentially expressed salivary proteins in bisphosphonate-related osteonecrosis of the jaw (BRONJ) patients that could serve as biomarkers for BRONJ diagnosis. SUBJECTS AND METHODS Whole saliva obtained from 20 BRONJ patients and 20 controls were pooled within groups. The samples were analyzed using iTRAQ-labeled two-dimensional liquid chromatography-tandem mass spectrometry. RESULTS Overall, 1340 proteins were identified. Of these, biomarker candidates were selected based on P-value (<0.001), changes in protein expression (≥1.5-fold increase or decrease), and unique peptides identified (≥2). Three comparisons made between BRONJ and control patients identified 200 proteins to be differentially expressed in BRONJ patients. A majority of these proteins were predicted to have a role in drug metabolism and immunological and dermatological diseases. Of all the differentially expressed proteins, we selected metalloproteinase-9 and desmoplakin for further validation. Immunoassays confirmed increased expression of metalloproteinase-9 in individual saliva (P = 0.048) and serum samples (P = 0.05) of BRONJ patients. Desmoplakin was undetectable in saliva. However, desmoplakin levels tended to be lower in BRONJ serum than controls (P = 0.157). CONCLUSIONS Multiple pathological reactions are involved in BRONJ development. One or more proteins identified by this study may prove to be useful biomarkers for BRONJ diagnosis. The role of metalloproteinase-9 and desmoplakin in BRONJ requires further investigation.

Hypercementosis Associated with ENPP1 Mutations and GACI

Mineralization of bones and teeth is tightly regulated by levels of extracellular inorganic phosphate (Pi) and pyrophosphate (PPi). Three regulators that control pericellular concentrations of Pi and PPi include tissue-nonspecific alkaline phosphatase (TNAP), progressive ankylosis protein (ANK), and ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). Inactivation of these factors results in mineralization disorders affecting teeth and their supporting structures. This study for the first time analyzed the effect of decreased PPi on dental development in individuals with generalized arterial calcification of infancy (GACI) due to loss-of-function mutations in the ENPP1 gene. Four of the 5 subjects reported a history of infraocclusion, overretained primary teeth, ankylosis, and/or slow orthodontic tooth movement, suggesting altered mineral metabolism contributing to disrupted tooth movement and exfoliation. All subjects had radiographic evidence of unusually protruding cervical root morphology in primary and/or secondary dentitions. High-resolution micro–computed tomography (micro-CT) analyses of extracted primary teeth from 3 GACI subjects revealed 4-fold increased cervical cementum thickness (P = 0.00007) and a 23% increase in cementum density (P = 0.009) compared to age-matched healthy control teeth. There were no differences in enamel and dentin densities between GACI and control teeth. Histology revealed dramatically expanded cervical cementum in GACI teeth, including cementocyte-like cells and unusual patterns of cementum resorption and repair. Micro-CT analysis of Enpp1 mutant mouse molars revealed 4-fold increased acellular cementum thickness (P = 0.002) and 5-fold increased cementum volume (P = 0.002), with no changes in enamel or dentin. Immunohistochemistry identified elevated ENPP1 expression in cementoblasts of human and mouse control teeth. Collectively, these findings reveal a novel dental phenotype in GACI and identify ENPP1 genetic mutations associated with hypercementosis. The sensitivity of cementum to reduced PPi levels in both human and mouse teeth establishes this as a well-conserved and fundamental biological process directing cementogenesis across species (ClinicalTrials.gov NCT00369421).