Purpose: Surface pre-reacted glass-ionomer (S-PRG) fillers reportedly possess ion-releasing properties and exhibit bioactive effects. The purpose of this study was to evaluate the biocompatibility of a zinc oxide based sealer containing S-PRG fillers (S-PRG sealer) compared with zinc oxide eugenol (ZOE) and non eugenol (ZO) sealers.

 Method: MC3T3-E1 cells were seeded on disks of S-PRG, ZOE and ZO sealers. Observations by scanning electron microscopy (SEM) and cell viability assay were carried out. Subsequently, each specimen was implanted into dorsal subcutaneous tissue of rats. After 10 and 35 days, the degree of inflammatory cell infiltration was evaluated by light microscopy using histological samples.

 Results: SEM observation revealed cell proliferation on S-PRG sealer, but not on ZOE and ZO sealers. Cell viability on S-PRG sealer was significantly greater than that on ZOE and ZO sealers. At 10 days after implantation into rat subcutaneous tissue, all samples showed inflammatory cell infiltration, however, S-PRG sealer tended to cause a milder inflammatory response than ZOE and ZO sealers. Ten-day inflammation scores of S-PRG, ZOE and ZO sealers were 2.16, 2.67 and 2.83, respectively. At 35 days after implantation, inflammatory cells were rarely found around the S-PRG sealer. Inflammation scores of S-PRG, ZOE and ZO sealers at 35 days were 0.00, 0.67 and 0.67, respectively.

 Conclusion: S-PRG sealer possesses superior biocompatibility compared to ZOE and ZO sealers.

 Purpose: To compare the anti-demineralization effects on dentin of a varnish containing surface reaction-type prereacted glass-ionomer (S-PRG) filler as a multi-ion releasing filler and one containing 1.0% NaF which releases an equivalent amount of fluoride.

 Methods: Before the demineralization study, we measured the amounts of fluoride ions released from NaF varnish (1.0 FV; 1.0% NaF＋40% silica filler, Shofu, Japan) and PRG varnish (PV; 40% S-PRG filler, Shofu, Japan), and confirmed that those concentrations were equivalent. 5-mm-thick root cylinders were prepared from lower bovine incisors and were cut into halves longitudinally using a diamond-coated wire sectioning machine (Well type 3242). Specimens (n=18) were divided into three groups of six: 1) Control (CONT; no coating), 2) NaF varnish (FV), and 3) PRG varnish (PV). An experimental surface on each specimen was prepared and coated according to group. The specimens were then immersed in 6 ml of deionized water at 37℃ for 3 days, after which the varnish was rubbed off with a cotton swab. Acid-resistant varnish was applied, exposing a 1×3 mm window, then the specimens were immersed in an 8% methylcellulose gel demineralization system (1.5 mmol/l CaCl₂, 0.9 mmol/l KH₂PO₄, 50 mmol/l acetic acid, pH 5.0) at 37℃ for 1 week. Then 300 μm-thick sections were cut from each specimen perpendicular to the experimental surface, and mineral profiles, integrated mineral loss (IML: vol%×μm) and lesion depth (Ld: μm) were obtained by transverse microradiography and dedicated software (TMR 2006 and 2012). Statistical difference of IML and Ld were analyzed with one-way ANOVA and Games-Howell test with α=0.05.

 Results: The average mineral profile and surface mineral density of 1.0 FV and PV were 27%. That of the lesion body of PV was 18%. PV showed significantly lower integrated mineral loss (2,523±121) than CONT (3,200±184, ANOVA, Games-Howell’s, p<0.05), however, there was no significant difference between CONT and FV (2,817±149). For Ld, there was no significant difference between the groups. S-PRG filler contained in PRG varnish released several ions providing buffering and anti-demineralization activity. Once those ions had penetrated into the root dentin, the anti-demineralization effect remained.

 Conclusion: PRG varnish helps to maintain an anti-demineralization effect under the dentin surface even after the varnish containing S-PRG has been removed.

 Purpose: We report a case of chronic suppurative apical periodontitis accompanied by a sinus tract that appeared some distance from the causative tooth identified by using dental cone beam computed tomography (CBCT).

 Case: The patient was a 45-year-old man with a sinus tract in the gingiva at the apical region between the left maxillary lateral incisor and canine. An intraoral radiograph was taken to identify the cause of the sinus tract. A radiolucent area was observed around the left maxillary canine and was diagnosed as chronic suppurative apical periodontitis. As the first step of root canal treatment, access opening was initiated, but then suspended due to pain. The referring dentist suspected chronic suppurative apical periodontitis of the canine and the patient was referred to Tokyo Dental College, Suidobashi Hospital for further evaluation. A careful examination was carried out using CBCT, which presented a bone defect at the apical lesion of the left maxillary first premolar that passed through the palatal side of the left maxillary canine. The cortical bone between the canine and the lateral incisor was completely absorbed. The causative tooth was identified as the left maxillary first premolar, not the canine. Root canal treatment was performed on the infected root canal, including the application of calcium hydroxide, and the sinus tract disappeared.

 Result: In this case, it was difficult to identify the causative tooth only by the patient’s symptoms, visual examination, and intraoral radiography. However, the use of CBCT allowed a simple and accurate identification. We found CBCT to be effective in identifying the causative tooth during endodontic treatment.