Effect of fit and self-etching adhesive on fiber post retention in endodontically treated teeth.

BACKGROUND: Fiber post (FP) reinforced restoration was widespread in endodontically treated teeth, of which the retention was closely related to fit and operation process. However, the question whether the fit and self-etching adhesive (SED) affect the success of FP restoration still remained unclear. OBJECTIVE: This research aimed to assess how the fit and self-etching adhesive (SED) impact the pull-out bond strength (BS) of glass fiber-reinforced composite posts from the root canal dentin. METHODS: Eighty lower first premolars underwent simulated endodontic treatment, after which their canals were shaped to accommodate a size three RelyX fiber post (FP) (diameter 1.9 mm). They were then divided into 4 equal groups [Unfit post and no SEA (Group UN), Fit post and no SEA (Group FN), Unfit post with SEA (Group UA) and Fit post with SEA (Group FA)] using two different sized FPs and SEA. Cement thickness was acquired by histological analysis and stereomicroscopy. Each sample was tested for pull-out strength through a universal testing machine. Based on the pull-out test, the failure types were observed and scored by visualizing through a stereomicroscope. RESULTS: Group FA demonstrated significantly greater BS compared to Group UN and Group UA, with Group UN showing a statistically significant difference at p< 0.01 and Group UA at p< 0.05. Main failure types in Group FA were Type II, which illustrated that the cement detachment mainly occurred from the post-cement interface. Therefore, Group FA possessed the STRONGEST BS and was most suitable for FP-reinforced crown restorations. CONCLUSIONS: Both the fit and SEA enhanced the pull-out BS. The SEA was critical for BS promotion when the mechanical retention was inadequate.

Study of the intentional replantation procedure used to treat a tooth with a palatogingival groove: A case report.

In order to clarify the prognosis of intentional replantation used for palatogingival groove treatment for long-term follow-up observation, the case of a patient with a maxillary lateral incisor with palatogingival groove was investigated. The intentional replantation was carried out to preserve the tooth. The periodontal pocket and the apical bone defect were almost completely repaired at 12-month follow-up. However, the infection was reoccurred after 25-month follow-up examinations. The infected tooth was extracted, of which the root was investigated by histological analysis. Therefore, the reason of the replant failure and the pathways of bacterial infection was investigated. Key words:Palatogingival groove, intentional tooth replantation, bacterial infection, maxillary lateral incisor.

Activation of calcium signaling in human gingival fibroblasts by recombinant Porphyromonas gingivalis RgpB protein.

Arginine-specific cysteine proteinases, such as Arg-gingipain B (RgpB), mediate inflammation by activating protease-activated receptors (PARs). Arg-gingipain B is produced by Porphyromonas gingivalis, and is implicated in the causation of periodontal disease. The purpose of the present study was to observe the influence of recombinant RgpB protein (rRgpB) on PAR activation by monitoring intracellular Ca2+ ion concentration ([Ca2+]i) and inositol-1,4,5-triphosphate (IP3) levels in human gingival fibroblasts (HGFs). Our findings showed that rRgpB could cause a transient increase in [Ca2+]i. This increase in [Ca2+]i was completely suppressed by vorapaxar, a PAR-1 antagonist. Recombinant Arg-gingipain B increased the concentration of IP3, reaching a maximum at 60 s after treatment; this was completely inhibited by vorapaxar. We therefore conclude that rRgpB-induced calcium signaling in HGFs is mainly caused by PAR-1 activation. This suggests that PAR-1 activation plays a significant role in chronic inflammatory periodontal disease induced by P. gingivalis RgpB.

Modulation of protease-activated receptor expression by Porphyromonas gingivalis in human gingival epithelial cells.

BACKGROUND: Protease-activated receptors (PARs) are G-protein-coupled receptors with an active role in mediating inflammation, pain and other functions. The oral pathogen Porphyromonas gingivalis (P. gingivalis) secretes proteases that activate PARs. The aim of this study was to elucidate the role of PARs in the pathogenesis of chronic periodontitis by expression analysis of PARs in human gingival epithelial cells (GECs) before and after P. gingivalis supernatants treatment. METHODS: GECs were isolated from healthy human gingival tissue samples. The expression of PARs in GECs was determined by reverse transcription-polymerase chain reaction (RT-PCR) and flow cytometry. The effect of P. gingivalis proteases was investigated by quantitative real-time reverse transcription polymerase chain reaction (QRT-PCR) and flow cytometry. RESULTS: PAR-1, PAR-2, and PAR-3 were expressed in GECs. PAR-4 was not found by both RT-PCR and flow cytometry. Analysis of gene expression using QRT-PCR showed an up-regulation of PAR-2 mRNA in comparison to the untreated control cells (P < 0.05). In contrast, the mRNA expressions of PAR-1 and PAR-3 were significantly down-regulated (P > 0.05) in response to P. gingivalis supernatant compared to that in unstimulated control cells. This effect was abrogated by the protease inhibitor TLCK (P < 0.05). The results of flow cytometry indicated PARs protein levels consistent with mRNA levels in the results of QRT-PCR. CONCLUSIONS: Our study shows that PAR-1, PAR-2 and PAR-3 are expressed in GECs. P. gingivalis proteases play a role in the regulation of innate immune responses in GECs. GECs use PARs to recognize P. gingivalis and mediate cell responses involved in innate immunity.

Replacement of severely traumatized teeth with immediate implants and immediate loading: literature review and case reports.

One of the options for management of severely traumatized dentitions is to provide immediate implant placement with immediate loading. Three representative cases out of 15 patients with 23 traumatized teeth treated to date in our clinic are presented. None had labial bone fractures. The teeth were replaced with NobelReplace Groovy implants (Nobel Biocare, Gothenburg, Sweden) in the fresh sockets immediately after extraction. They were placed toward the palatal areas in the sockets and 3 mm below the gingival margins. If there were gaps between implants and sockets wider than 1 mm, particulate deproteinized bovine bone was grafted in the gaps. Immediately after placement, the implants were loaded with provisional prostheses. The final restorations were installed 3-4 months later. The patients were reevaluated clinically and radiographically 1-3 years after the final restorations had been placed. In all 15 patients, excellent functional and esthetic results were achieved. No implants showed radiolucency, peri-implant suppuration, or mobility. The patients were satisfied with the results. Immediate implant placement with immediate loading is an option that provides good treatment outcomes and allows good functional and esthetic results, as well as addressing the social/psychological aspects of dental trauma.

[Expressions of protease-activated receptors in human gingival fibroblasts and its functions in periodontitis].

OBJECTIVE: To investigate the expression types of protease-activated receptors(PAR) in human gingival fibroblasts(HGF) and the functions of PAR in periodontitis. METHODS: Primary HGF were cultured.Reverse transcription PCR(RT-PCR) was used to detect the expression of PAR in HGF. Recombinant gingipain R (rRgp) was applied to HGF. The change of PAR expression on the cell surface was analyzed by real-time quantitative RT-PCR, and enzyme-linked immunosorbent assay (ELISA) was used to detect the change of the interleukin (IL)-6 production from HGF. The results of RT-PCR and ELISA were statistically analyzed using the two independent samples t-test of SPSS10.0 software. RESULTS: HGF expressed PAR-1 and PAR-3. The expression of PAR-1 and PAR-3 changed after two rRgp treatment with HGF cells. The relative expression of PAR-1 was decreased from 1.04 ± 0.31 to 0.67 ± 0.11 and 0.31 ± 0.11. The relative expression of PAR-3 was decreased from 1.01 ± 0.44 to 0.79 ± 0.13 and 0.44 ± 0.12(P < 0.05). The level of IL-6 was increased after rRgp treatment for 8 h. The control group was (18.77 ± 4.09) µg/L, the rRgp treatment groups were (179.36 ± 15.81) and (320.56 ± 26.19) µg/L respectively. CONCLUSIONS: HGF expressed PAR-1 and PAR-3 and were involved in periodontal inflammation.

Protease-activated receptors expression in gingiva in periodontal health and disease.

OBJECTIVE: Protease-activated receptors (PARs) are a unique class of receptors which are implicated in mediating inflammation, pain and other functions. The aim of this study was to elucidate the role of PARs in the pathogenesis of chronic periodontitis by differential expression analysis of PARs in the gingival tissues of chronic periodontitis patients compared with those of healthy control individuals. DESIGN: Gingival tissue specimens were collected from chronic periodontitis patients (n=20) and control individuals (n=20). The expression of PAR-1, -2, -3 and -4 was determined in these tissues by immunohistochemistry and differential expression between the two groups was investigated by quantitative real-time reverse transcription-polymerase chain reaction analysis. RESULTS: PAR-1, -2, -3 and -4 were expressed in all gingival tissues. A significant overexpression of PAR-3 was detected in chronic periodontitis-affected tissues compared to healthy gingival tissues. However, expression of PAR-2 was decreased in periodontal lesions. CONCLUSIONS: Our study shows that PAR-1, -2, -3 and -4 are expressed in both healthy and inflamed gingival tissues. Furthermore, PAR-2 and PAR-3 may contribute to the inflammatory responses associated with chronic periodontitis.