Faculty Bibliography

INTRODUCTION: The unique innervation and anatomic features of dental pulp contribute to the remarkable finding that any physical stimulation of pulpal tissue is painful. Furthermore, when pathological processes such as caries affect teeth and produce inflammation of the pulp, the pain experienced can be quite intense and debilitating. To better understand these underlying neurobiological mechanisms and identify novel analgesic targets for pulpally derived pain, we have developed a powerful ex vivo model using human tooth slices. METHODS: Noncarious, freshly extracted teeth were collected and sectioned longitudinally into 1-mm-thick slices containing both dental pulp and the surrounding mineralized tissues. Tooth slices from 36 patients were exposed to 60 mumol/L capsaicin to stimulate the release of calcitonin gene-related peptide (CGRP) from nerve terminals in the pulp. Patient factors were analyzed for their effects on capsaicin-stimulated CGRP release using a mixed model analysis of variance. RESULTS: Approximately one third of the variability observed in capsaicin-evoked CGRP release was attributable to differences between individuals. In terms of individual factors, there was no effect of anesthesia type, sex, or age on capsaicin-stimulated CGRP release. Using a within-subject study design, a significant effect of capsaicin on CGRP release was observed. CONCLUSIONS: Capsaicin-stimulated CGRP release from dental pulp is highly variable between individuals. A within-subject study design improves the variability and maximizes the potential of this powerful translational model to test the efficacy of novel pharmacotherapeutic agents on human peripheral nociceptors.

INTRODUCTION: Regenerative endodontic therapy (RET) is currently used to treat immature teeth with necrotic pulp and/or apical periodontitis. However, recently RET has been used to treat mature teeth with necrotic pulp and/or apical periodontitis and resulted in regression of clinical signs and/or symptoms and resolution of apical periodontitis. The purpose of this case report was to describe the potential of using RET to treat 2 mature teeth with persistent apical periodontitis after root canal therapy using RET. METHODS: Two male patients, one 26-year old and another 12-year old, presented for retreatment of persistent apical periodontitis after root canal treatment of 2 mature teeth (#9 and #19). The gutta-percha fillings in the canals of teeth #9 and #19 were removed with Carvene gutta-percha solvent (Prevest DenPro, Jammu, India) and ProTaper Universal rotary retreatment files (Dentsply Maillefer, Ballaigues, Switzerland). The canals of both teeth were further chemomechanically debrided with rotary retreatment files and copious amounts of sodium hypochlorite irrigation and dressed with Metapaste (Meta Biomed, Chungbuk, Korea). RET was performed on teeth #9 and #19. Periapical bleeding was provoked into the disinfected root canals. The blood clots were covered with mineral trioxide aggregate plugs, and the access cavities were restored with intermediate restorative material. RESULTS: Teeth #9 and #19 showed regression of clinical signs and/or symptoms and healing of apical periodontitis after 13-month and 14-month follow-ups, respectively. Tooth #9 revealed narrowing of the canal space and apical closure by deposition of hard tissue. CONCLUSIONS: RET has the potential to be used to retreat teeth with persistent apical periodontitis after root canal therapy.

INTRODUCTION: Revascularization treatment is rapidly becoming an accepted treatment alternative for the management of endodontic pathology in immature permanent teeth with necrotic dental pulps. However, the success and timing of clinical resolution of symptoms, and radiographic outcomes of interest, such as continued hard tissue deposition within the root, are largely unknown. METHODS: In this prospective cohort study, 20 teeth were treated with a standardized revascularization treatment protocol and monitored for clinical and radiographic changes for 1 year. Standardized radiographs were collected at regular intervals, and radiographic changes were quantified. RESULTS: All 20 treated teeth survived during the 12-month follow-up period, and all 20 also met the clinical criteria for success at 12 months. As a group, the treated teeth showed a statistically significant increase in radiographic root width and length and a decrease in apical diameter, although the changes in many cases were quite small (such that the clinical significance is unclear). The within-case percent change in apical diameter after 3 months was 16% and had increased to 79% by 12 months, with 55% (11/20) showing complete apical closure. The within-case percent change in root length averaged less than 1% at 3 months and increased to 5% at 12 months. The within-case percent change in root thickness averaged 3% at 3 months and 21% at 12 months. CONCLUSIONS: Although clinical success was highly predictable with this procedure, clinically meaningful radiographic root thickening and lengthening are less predictable after 1-year of follow-up. Apical closure is the most consistent radiographic finding.

INTRODUCTION: The frequency of persistent pain 3-5 years after primary root canal therapy and its impact on the patient's perceived oral health-related quality of life was determined in a practice-based research network. METHODS: All patients presenting to participating network practices who received primary root canal therapy and restoration for a permanent tooth 3-5 years previously were invited to enroll. Persistent pain was defined as pain occurring spontaneously or elicited by percussion, palpation, or biting. The patient also completed an oral health-related quality of life questionnaire (Oral Health Impact Profile-14). RESULTS: Sixty-four network practices enrolled 1323 patients; 13 were ineligible, 12 did not receive a final restoration, and 41 were extracted, leaving 1257 for analysis. The average time to follow-up was 3.9 +/- 0.6 years. Five percent (63/1257) of the patients reported persistent pain, whereas 24 of 63 (38%) exhibited periapical pathosis and/or root fracture (odontogenic pain). No obvious odontogenic cause for persistent pain was found for 39 of 63 (62%). Teeth treated by specialists had a greater frequency of persistent pain than teeth treated by generalists (9.3% vs 3.0%, respectively; P < .0001). Sex, age, tooth type, type of dentist, and arch were not found to be associated with nonodontogenic persistent pain; however, ethnicity and a preoperative diagnosis of pulpitis without periapical pathosis were. Patients reporting pain with percussion tended to experience pain with other stimuli that negatively impacted quality of life including oral function and psychological discomfort and disability. CONCLUSIONS: These results suggest that a small percentage (3.1%) of patients experience persistent pain not attributable to odontogenic causes 3-5 years after primary root canal therapy that may adversely impact their quality of life.

INTRODUCTION: This retrospective cohort study compared clinical and radiographic outcomes of endodontic treatment performed in immature nonvital permanent teeth by apexification (calcium hydroxide or apical barrier with mineral trioxide aggregate) versus revascularization. METHODS: A comprehensive chart review was performed to obtain a cohort of previously completed cases with recalls. Clinical and radiographic data were collected for 31 treated teeth (19 revascularization and 12 apexification) with an average follow-up time of 17 months and a recall rate of 63%. Tooth survival, success rate, and adverse events were analyzed. Changes in radiographic root length, width, and area were quantified. RESULTS: The majority of treated teeth survived throughout the study period, with 30 of 31 (97%) teeth surviving (18/19 [95%] revascularization and 12/12 apexification). Most cases were also clinically successful, with 27 of 31 (87%) meeting criteria for success (15/19 [78%] revascularization and 12/12 apexification; nonsignificant difference). A greater incidence of adverse events was observed in the revascularization group (8/19 [42%] vs 1/12 [11%] in apexification) (risk ratio = 5.1; P = .04; 95% confidence interval, 0.719-35.48). Although more revascularization cases than apexification cases showed an increase in radiographic root area and width, the effect was not statistically significant. CONCLUSIONS: In this study, revascularization was not superior to other apexification techniques in either clinical or radiographic outcomes. Studies with large subject cohorts and long follow-up periods are needed to evaluate outcomes of revascularization and apexification while accounting for important covariants relevant to clinical success.

BACKGROUND: The authors conducted a study of tweets posted on Twitter to compare self-reported toothache experiences with those of backache, earache and headache in regard to pain intensity, action taken, perceived cause and effect of pain. METHODS: From a total of 508,591 relevant tweets collected on seven nonconsecutive days, the authors randomly selected 1,204 tweets (301 per pain type) and conducted content analyses of each tweet. RESULTS: Toothaches were described as having higher pain intensity than were earaches or headaches but pain intensity comparable with that of backaches. Despite people who experience toothache being more likely to seek health care than those experiencing backaches (odds ratio [OR], 3.91; 95 percent confidence interval [CI], 1.57-9.71) or headaches (OR, 6.11; 95 percent CI, 2.16-17.25), only one in 10 people with toothaches mentioned seeking health care for their pain. People with toothaches were less likely to report an effect on daily functioning compared with those with backaches (OR, 0.13; 95 percent CI, 0.03-0.56) or earaches (OR, 0.19; 95 percent CI, 0.05-0.77). CONCLUSIONS: Using unsolicited self-reported data from Twitter, the authors found similarities and differences in the experiences of people with toothaches compared with those of people with other common pains. These findings offer insights into understanding dental pain and dental care utilization. PRACTICAL IMPLICATIONS: The use of social media, such as Twitter, to discuss health issues provides opportunities for dental professionals to better understand dental care experiences from the patients' perspective. Furthermore, social media such as Twitter offer providers the opportunity to share information with the public and to facilitate provider-patient communication.

INTRODUCTION: Mechanical debridement plays an important role in eliminating intracanal bacteria, such as biofilm on the canal walls and bacteria in the dentinal tubules. Mechanical debridement is not recommended for root canal disinfection in revascularization/revitalization therapy. Here we report a failed revascularization/revitalization case, which could be due to inadequate root canal disinfection without mechanical removal of biofilm and bacteria in dentinal tubules. METHODS: A 6-year-old boy had a traumatic injury to tooth #9, which was avulsed and replanted within 40 minutes. The tooth subsequently developed a local swelling in the periapical area. The patient was referred to the Postgraduate Endodontic Clinic for revascularization/revitalization therapy on tooth #9. The treated tooth remained asymptomatic for 16 months and then developed pain and local periapical swelling. The oral surgeon extracted the revascularized/revitalized tooth. On request, the extracted tooth was processed for histologic and histobacteriologic examination. RESULTS: The tissue in the canal was completely destroyed. Most bacteria were observed in the apical portion and not in the coronal portion of the canal and formed biofilm on the canal walls and penetrated into the dentinal tubules. CONCLUSIONS: On the basis of histobacteriologic observations, the failure of revascularized/revitalized tooth could be due to inadequate root canal disinfection without mechanical debridement. It may be important to perform mechanical debridement as part of the revascularization/revitalization therapy to disrupt the biofilm on the canal walls and remove bacteria in the dentinal tubules because revascularization/revitalization therapy is able to increase thickening of the canal walls.

INTRODUCTION: Histologic studies of teeth from animal models of revascularization/revitalization are available; however, specimens from human studies are lacking. The nature of tissues formed in the canal of human revascularized/revitalized teeth was not well established. METHODS: An immature mandibular premolar with infected necrotic pulp and a chronic apical abscess was treated with revascularization/revitalization procedures. At both the 18-month and 2-year follow-up visits, radiographic examination showed complete resolution of the periapical lesion, narrowing of the root apex without root lengthening, and minimal thickening of the canal walls. The revascularized/revitalized tooth was removed because of orthodontic treatment and processed for histologic examination. RESULTS: The large canal space of revascularized/revitalized tooth was not empty and filled with fibrous connective tissue. The apical closure was caused by cementum deposition without dentin. Some cementum-like tissue was formed on the canal dentin walls. Inflammatory cells were observed in the coronal and middle third of revascularized/revitalized tissue. CONCLUSIONS: In the present case, the tissue formed in the canal of a human revascularized/revitalized tooth was soft connective tissue similar to that in the periodontal ligament and cementum-like or bone-like hard tissue, which is comparable with the histology observed in the canals of teeth from animal models of revascularization/revitalization.