Inorganic polyphosphate [Poly(P)] is especially prevalent in osteoblasts. We tested the hypothesis that Poly(P) stimulates osteoblastic differentiation and polyphosphate metabolism for bone formation. The osteoblast-like cell line, MC 3T3-E1, was cultured with Poly(P), and gene expression was evaluated by real-time reverse-transcription polymerase chain-reaction. Phosphatase activity and extracellular matrix mineralization were also determined. The role of Poly(P) was assessed in a beagle dog alveolar bone regeneration model. Poly(P) increased osteocalcin, osterix, bone sialoprotein, and tissue non-specific alkaline phosphatase gene expression, with a high level of end-polyphosphatase activity, resulting in low-chain-length Poly(P), inorganic pyrophosphate, and inorganic phosphate production. MC3T3-E1 cells differentiated into mature osteoblasts and showed expression of ectonucleotide pyrophosphatase phosphodiesterase 1, while mouse progressive ankylosis gene expression remained unchanged. Promotion of alveolar bone regeneration was observed in Poly(P)-treated beagle dogs. These findings suggest that Poly(P) induces osteoblastic differentiation and bone mineralization, and acts as a resource for mineralization.

Inorganic polyphosphate was useful in the treatment of periodontitis in the elderly, indicating a probable effect of anti-ageing, with similar bone regenerations occurring in both groups.

Although radiolucency has been shown as a risk of infection, the poorly understood effects of aging on radiolucency correlate with acute pericoronitis, which has a high risk of infection extending any complications. We reviewed the records of 346 consecutive patients aged more than 41 years to evaluate whether pericoronal radiolucency below the crown in mandibular horizontal incompletely impacted third molars is related to acute inflammation. The frequency of acute inflammation in teeth with pericoronal radiolucency below the crown was similar to that in teeth without; however, the odds ratio of acute inflammation exhibited in women aged more than 61 years compared to women aged 41–50 years was 9.77 (95% confidence interval [CI]: 1.67–57.29; P < <0.05), and in women aged more than 61 years compared to women aged 51–60 years was 26.25 (95% CI: 2.94–234.38; P < 0.01). The odds ratio of severe acute inflammation exhibited in men aged more than 61 years compared to men aged 41–50 years was 16.67 (95% CI: 1.76–158.27; P < 0.01). These odds ratios indicate an association of acute pericoronitis, including the severe forms of acute inflammation that result from pericoronitis, with pericoronal radiolucency below the crown in the elderly.

Acute inflammation is frequently seen in the elderly around incompletely impacted molars located apart from molars or premolars. To identify the factors causing acute inflammation in the solitary molars without second molars or without second and first molars, ages of patients and rates of acute inflammation in 75 horizontal incompletely impacted mandibular molars in contact or not in contact with molars in subjects 41 years old or older were studied using orthopantomographs. Acute inflammation was seen in nine third molars out of 48 third molars in contact with second molars (18.8%), whereas acute inflammation was seen in 11 molars out of 19 solitary molars without second molars or without first and second molars (57.9%) (p < 0.01). The mean age of 48 subjects with third molars in contact with the second molar was 50.42 ± 7.62 years, and the mean age of 19 subjects with isolated molars was 65.16 ± 10.41 years (p < 0.0001). These indicate that a solitary horizontal incompletely impacted molar leads more frequently to acute inflammation along with aging due to possible bone resorption resulting from teeth loss.

Although mandibular third molar has a high risk of infection extending any complications, the influence of diabetes on radiolucency and acute inflammation in pericoronitis remains unclear. The present study was to evaluate whether radiolucency below the crown is related to acute inflammation in mandibular horizontal incompletely impacted third molars and to review the records of 140 men more than 45 years with and without diabetes. The odds ratio of exhibiting acute inflammation was 3.38 (95% CI: 1.13-10.16, p  0.05) and that of exhibiting severe acute inflammation was 15.38 (95% CI: 3.56-66.49, p  0.0001), indicating an association of acute pericoronitis in diabetes. The frequency of radiolucency below the crown and below the root in diabetics was similar to that in nondiabetics. However, the odds ratio of exhibiting both radiolucency below the crown and acute inflammation under the diabetic condition was 4.85 (95% CI: 1.60-14.73, p  0.01), whereas that of diabetics showing both radiolucency below the root and acute inflammation was 0.46 (95% CI: 0.06-3.74, p = 0.74). Radiolucency below the crown and acute inflammation were associated with diabetes, but that below root and acute inflammation were not associated with diabetes, indicating that the region below the crown carries susceptibility to acute pericoronitis, whereas the periodontium shows a protective effect against acute pericoronitis.