Pulpal upregulation of connexin 43 during pulpitis.

OBJECTIVES: Connexins are building blocks of membranous channels that form gap junctions and hemichannels. These channels are essential portals for information exchange and coordination during inflammation. Pathologic levels of these conduits may result in excessive inflammation and collateral destruction. This study aimed to analyse temporospatial levels of connexin 43 (Cx43) during pulpitis in extracted human teeth and in a rodent model. A specific interest was directed at the pulpal stroma as it is conserved during vital pulp therapy. MATERIALS AND METHODS: Pulpal tissues were attained from human extracted teeth of various pulpal inflammatory stages and fixed for cryosections. Pulpal exposures were created in bilateral maxillary molars in Sprague-Dawley rats. Rats were sacrificed at days 1 to 5 post-exposure. Immunofluorescence histology was performed to detect Cx43, markers for inflammation, and cell death. Immunofluorescent levels in the pulpal stroma at 3 sites (wound/near/far) were matched to pulpal condition (human) or days post-exposure (rodent). RESULTS: Cx43 upregulation was observed with increased severity of pulpitis both in humans and rodent model. The upregulation appeared to be global and included distant regions. Elevated levels of neutrophils were present in advanced pulpitis. Apoptosis and necroptosis seem to be upregulated in human samples as Cx43 levels rose. CONCLUSIONS: We observed a disseminated upregulation of Cx43 throughout the pulpal stroma as inflammation became advanced. This observation may facilitate cell death signal transfer or represent overt levels of purinergic signalling that leads to pro-inflammatory conditions. CLINICAL RELEVANCE: Cx43 downregulation may represent a potential therapeutic approach to enable resolution of pulpal inflammation.

Factors Affecting the Decision-making of Direct Pulp Capping Procedures among Dental Practitioners: A Multinational Survey from 16 Countries with Meta-analysis.

INTRODUCTION: Direct pulp capping (DPC) procedures require the placement of a bioactive material over an exposure site without selective pulp tissue removal. This web-based multicentered survey had 3 purposes: (1) to investigate the factors that affect clinicians' decisions in DPC cases, (2) to determine which method of caries removal is preferred, and (3) to evaluate the preferred capping material for DPC. METHODS: The questionnaire comprised 3 sections. The first part comprised questions regarding demographic features. The second part comprised questions on how treatment plans change according to factors such as nature, location, number and size of the pulp exposure, and patients' age. The third part composed of questions on the common materials and techniques used in DPC. To estimate the effect size, the risk ratio (RR) and 95% confidence interval (CI) were calculated using a meta-analysis software. RESULTS: A tendency toward more invasive treatment was observed for the clinical scenario with carious-exposed pulp (RR = 2.86, 95% CI: 2.46, 2.32; P < .001) as opposed to the clinical scenario with 2 pulp exposures (RR = 1.38, 95% CI: 1.24, 1.53; P < .001). Complete caries removal was significantly preferred to selective caries removal (RR = 4.59, 95% CI: 3.70, 5.69; P < .001). Among the capping materials, calcium silicate-based materials were preferred over calcium hydroxide-based materials (RR = 0.58, 95% CI: 0.44, 0.76; P < .05). CONCLUSIONS: While carious-exposed pulp is the most important factor in clinical decisions regarding DPC, the number of exposures has the least impact. Overall, complete caries removal was preferred over selective caries removal. In addition, the use of calcium silicate-based materials appears to have replaced calcium hydroxide-based materials.

An Immunofluorescence Study to Analyze Wound Healing Outcomes of Regenerative Endodontics in an Immature Premolar with Chronic Apical Abscess.

INTRODUCTION: Limited studies have examined tissue formation via immunofluorescence in regenerative endodontic procedures (REPs) performed on infected human teeth. This report investigated the immunofluorescent histologic outcomes of REPs in which repeated canal disinfection was required. METHODS: An 11-year-old girl presented with a fractured dens evaginatus (#29) with a sinus tract. Three visits involving chemical and mechanical disinfection were required before the resolution of clinical signs and symptoms was achieved and the REP could be performed. Healing of the periapical lesion was noted by 12 months, although the tooth remained unresponsive to sensibility tests. At 18 months, the tooth underwent orthodontic extraction. Histology and immunofluorescent techniques were used to stain for dentin sialophosphoprotein (DSPP), osteopontin (OPN), periostin, and myelin basic protein. RESULTS: Histology did not reveal a newly formed pulp-dentin complex. Neomineralized tissues were seen interlocked into preexisting dentinal tubules. Non-odontoblast-looking cells expressed different proportions of OPN and DSPP according to their location. Cells nearer to mineral trioxide aggregate expressed DSPP and OPN, but cells found apically expressed predominantly OPN. Myelin basic protein was found centrally within new tissues and did not extend to the coronal third. Periostin was highly expressed throughout the entire canal space, suggesting active repair processes instead of regeneration. CONCLUSIONS: This study shows the clinical effectiveness of REP in a tooth with recalcitrant infection with histologic demonstration of a reparative phenotype. De novo pulp regeneration in a clinical scenario may be limited by a complex interplay of host response factors.