Bettina Basrani

Physical and Chemical Properties of Chlorhexidine and Calcium Hydroxide-Containing Medications

This study was performed to evaluate the physicochemical properties (pH, contact angle, working time, radio-opacity, and viscosity) of chlorhexidine (CHX) and calcium hydroxide-containing medications in gel form in different concentrations. The pH value was assessed with a pH meter. The contact angle was measured with a goniometer. The radio-opacity and working time measurements were taken in accordance with the standards of the International Organization for Standardization. The viscosity was evaluated using a Brookfield RVDV viscometer. The results showed that CHX did not affect the pH, radio-opacity, and working time of the calcium hydroxide-containing medications (p < 0.05). However, adding CHX lowered the contact angle and increased the viscosity of calcium hydroxide significantly. This research showed that CHX in different concentrations and in combination with calcium hydroxide has satisfactory physicochemical properties to be used as an intracanal medication.

Synergistic Effect of Microbubble Emulsion and Sonic or Ultrasonic Agitation on Endodontic Biofilm in Vitro

INTRODUCTION Irrigation dynamics and antibacterial activity determine the efficacy of root canal disinfection. Sonic or ultrasonic agitation of irrigants is expected to improve irrigation dynamics. This study examined the effects of microbubble emulsion (ME) combined with sonic or ultrasonic agitation on irrigation dynamics and reduction of biofilm bacteria within root canal models. METHODS Two experiments were conducted. First, high-speed imaging was used to characterize the bubble dynamics generated in ME by sonic or ultrasonic agitation within canals of polymer tooth models. Second, 5.25% NaOCl irrigation or ME was sonically or ultrasonically agitated in canals of extracted teeth with 7-day-grown Enterococcus faecalis biofilms. Dentinal shavings from canal walls were sampled at 1 mm and 3 mm from the apical terminus, and colony-forming units (CFUs) were enumerated. Mean log CFU/mL values were analyzed with analysis of variance and post hoc tests. RESULTS High-speed imaging demonstrated strongly oscillating and vaporizing bubbles generated within ME during ultrasonic but not sonic agitation. Compared with CFU counts in controls, NaOCl-sonic and NaOCl-ultrasonic yielded significantly lower counts (P < .05) at both measurement levels. ME-sonic yielded significantly lower counts (P = .002) at 3 mm, whereas ME-ultrasonic yielded highly significantly lower counts (P = .000) at both measurement levels. At 3 mm, ME-ultrasonic yielded significantly lower CFU counts (P = .000) than ME-sonic, NaOCl-sonic, and NaOCl-ultrasonic. CONCLUSIONS Enhanced bubble dynamics and reduced E. faecalis biofilm bacteria beyond the level achieved by sonic or ultrasonic agitation of NaOCl suggested a synergistic effect of ME combined with ultrasonic agitation.

Torsional Profiles of New and Used 20/.06 GT Series X and GT Rotary Endodontic Instruments

INTRODUCTION M-Wire (Sportswire LLC, Langley, OK) is reportedly created by altering alloy temperatures during the manufacturing process of GT series X instruments (Dentsply Tulsa Dental Specialties, Tulsa, OK). Currently, there are few published studies looking at torsional profiles of these instruments. The purpose of this study was to investigate the torsional profiles of new and used 20/0.06 GT series X (GTX) and GT (GT) instruments (Dentsply Tulsa Dental Specialties). METHODS Thirty instruments were allocated to one of eight groups and were used 2, 6, or 10 times in simulated canals or remained as unused controls. Testing of torque (TF) and angle at fracture (AF) were conducted in accordance with American National Standards Institute/American Dental Association (ANSI/ADA) specification No. 28. Data analyses were performed by using one- and two- way analysis of variance with honesty significance difference post hoc comparison with alpha = 0.05. RESULTS Overall, there were significant differences in TF and AF among the experimental groups (p < 0.001). GTX instruments showed a significant initial increase in TF with two and six uses (p < 0.001) in contrast to the GT, which showed a linear reduction in TF with increased use (p < 0.004). Both GTX and GT instruments showed no statistical difference in AF of new instruments but did show a significant decrease in AF in all groups except the GT two-use group (p < 0.02). CONCLUSION The GTX instruments had a higher resistance to torsional failure after use as compared with the GT.

Resolution of Maxillary Sinus Mucositis after Endodontic Treatment of Maxillary Teeth with Apical Periodontitis: A Cone-Beam Computed Tomography Pilot Study

INTRODUCTION Apical periodontitis (AP) is an inflammatory response that can affect the maxillary sinus. This study characterized maxillary sinus mucositis adjacent to teeth with AP and assessed its resolution after endodontic treatment. METHODS Thirty maxillary sinuses in subjects (n = 29) who had AP associated with maxillary posterior teeth were imaged with cone-beam computed tomography (CBCT). When mucositis was detected, its resolution was assessed with CBCT scanning 3 months after treatment, and periapical healing was assessed using the periapical index (PAI) after 6 months. RESULTS Excluding 5 sinuses obscured by sinusitis, mucositis was detected in 14 of 25 sinuses (56%). Nonsignificant inverse association was observed between the mucosal lining thickness and the distance from the sinus to root apices with AP. Four noncompliant subjects were discontinued. Three months after treatment, mucositis was fully resolved in 3 of 10 subjects (30%), partially resolved in 3 of 10 subjects (30%), unchanged in 3 of 10 subjects (30%), and worsened in 1 subject (10%). Six months after treatment, 6 of 10 subjects (60%) had reduced PAI scores classified as healed or healing. The subject with expanded mucositis at 3 months was not healing at 6 months. CONCLUSIONS Within the limited sample of this pilot study, CBCT imaging revealed a lower-than-expected prevalence of mucositis adjacent to teeth with AP. Fully resolved mucositis was not common 3 months after endodontic treatment, suggesting that in specific cases it might linger beyond 3 months after the elimination of the endodontic infection. Because of the low statistical power, the association between the resolution of mucositis and periapical healing could not be explored.

Biofilm Formation within the Interface of Bovine Root Dentin Treated with Conjugated Chitosan and Sealer Containing Chitosan Nanoparticles

INTRODUCTION The purpose of this study was to assess biofilm formation within sealer-dentin interfaces of root segments filled with gutta-percha and sealer incorporated with chitosan (CS) nanoparticles with and without canal surface treatment with different formulations of CS. METHODS Standardized canals of 4-mm bovine root segments (N = 35) were filled with gutta-percha and pulp canal sealer incorporated with CS nanoparticles without surface treatment (group CS) or after surface treatment with phosphorylated CS (group PHCS), CS-conjugated rose bengal and photodynamic irradiation (group CSRB), or a combination of both PHCS and CSRB (group RBPH). The control group was filled with gutta-percha and an unmodified sealer. After 7 days of setting, specimens were aged in buffered solution at 37°C for 1 or 4 weeks. Monospecies biofilms of Enterococcus faecalis were grown on specimens for 7 days in a chemostat-based biofilm fermentor. Biofilm formation within the sealer-dentin interface was assessed with confocal laser scanning microscopy. RESULTS In the 4-week-aged specimens only, the mean biofilm areas were significantly smaller than in the control for the CS (P = .008), PHCS (P = .012), and RBPH (P = .034) groups. The percentage of the biofilm-covered interface also was significantly lower than in the control for the CS (P = .024) and PHCS (P = .003) groups. The CS, PHCS, and RBPH groups did not differ significantly. CONCLUSIONS Incorporating CS nanoparticles into the zinc oxide-eugenol sealer inhibited biofilm formation within the sealer-dentin interface. This effect was maintained when canals were treated with phosphorylated CS, and it was moderated by canal treatment with CS-conjugated rose bengal and irradiation.

Efficacy of bacteriophage treatment on Pseudomonas aeruginosa biofilms.

INTRODUCTION Bacterial viruses (phages) have been used successfully in the treatment of animal and human bacterial infections. This study examined the potential use of phage therapy against Pseudomonas aeruginosa strain PA14 biofilms in a root canal model. METHODS Part 1: The 24-hour and 96-hour PA14 biofilms grown in microplates were treated with phages identified as possessing potential biofilm-degrading activities, and the post-treatment bacterial biomass was quantified by using crystal violet staining. Part 2: The 24-hour and 96-hour PA14 biofilms grown in prepared root canals of extracted human mandibular incisors were treated with phages identified with potential biofilm-degrading activities. Post-treatment intracanal samples were taken by using paper points and round burs to assess phage and bacterial counts. RESULTS Part 1: We identified 2 phages (JBD4 and JBD44a) with putative biofilm-degrading activities. Treatment of PA14 biofilms with these phages produced a significant reduction in the mean percentage of biomass in 24-hour (P< .05) and 96-hour (P= .08) biofilms. Part 2: In 24-hour and 96-hour PA14 biofilms in a root canal model, no significant difference was found in the number of colony-forming units after phage treatment (P> .05). CONCLUSIONS Phage application significantly reduced the biomass of 24-hour and 96-hour PA14 biofilms grown on microplates but did not produce significant reduction of 24-hour or 96-hour PA14 biofilms grown in the extracted tooth model.

Torsional Profiles of New and Used Revo-S Rotary Instruments: An In Vitro Study

INTRODUCTION This study investigated the torsional properties of new and used Revo-S Shaping Universal (SU) endodontic instruments. METHODS Torsional profiles were established following the American National Standards Institute/American Dental Association Specification No. 28. Unused SU instruments (group 1, control; n = 30) and instruments used in simulated root canals twice (group 2, n = 30) or six times (group 3, n = 30) were tested. Analysis of variance with the Bonferroni/Dunn post hoc test (α = 0.05) was used to analyze the torque and angle of rotation at fracture. RESULTS The maximum torque at fracture did not differ significantly among instruments in group 1 and groups 2 and 3. The angle of rotation at fracture decreased significantly (P < .01) from group 1 to groups 2 and 3. CONCLUSIONS The repeated use of the SU rotary instruments significantly reduced the angle of rotation at fracture but did not reduce the torque at fracture.

Proportion of Healed Teeth With Apical Periodontitis Medicated With Two Percent Chlorhexidine Gluconate Liquid: A Case-Series Study

INTRODUCTION Chlorhexidine gluconate (CHX) is a potential intracanal medicament, but data on healing after its use are lacking. Previously we reported on bacterial sampling in 22 teeth with apical periodontitis medicated with CHX. This study assessed healing in those teeth. METHODS Canals were instrumented and medicated with 2% CHX liquid for 7-15 days and subsequently irrigated and filled. Bacterial samples were taken before and after instrumentation, after medication and before root filling, and enumerated by culture and vital microscopy. After 2-4 years, subjects were examined clinically and radiographically by assigning Periapical Index scores by independent calibrated examiners. Outcome was dichotomized as healed or disease. RESULTS With 2 teeth extracted, 1 deceased subject, and 2 nonrespondents, 16 of 17 examined teeth (94%) were healed without association with bacterial sampling results. The proportion of healed teeth in this study did not differ significantly (Fisher exact test; P = .20) from that in a historical control (90%). CONCLUSIONS The results suggested a comparable outcome after medication with 2% CHX liquid and calcium hydroxide.

Possibilities of Gutta-Percha-centered Infection in Endodontically Treated Teeth: An In Vitro Study

INTRODUCTION Implanted biomaterials could provide surface for bacterial adherence and formation of biofilm, eventually leading to biomaterial-centered infections (BCIs). In this in vitro study, we examined the biofilm-forming capacity of Enterococcus faecalis on gutta-percha (GP) points under different nutrient status and surface conditioning with saliva and serum. METHODS GP points (n = 420) coated with different root canal sealers (Sealapex or Roth) were conditioned with saliva or serum for 2-, 4-, and 12-week intervals and subsequently were incubated with E. faecalis for 2 weeks under nutrient-rich and nutrient-deprived environments. The biofilm-forming capacity and the nature of biofilm formed on GP were assessed by using a viable cell assay and scanning electron microscopy (SEM). RESULTS E. faecalis produced biofilms on GP points (with and without root canal sealers) under both nutrient-rich and nutrient-deprived environments after conditioning with saliva or serum. SEM reflected that the biofilms formed under nutrient-rich conditions were regular, whereas the biofilms formed under nutrient-deprived conditions were irregular and scanty. Under nutrient-deprived conditions, longer conditioning periods in saliva or serum were required for bacterial adherence. CONCLUSIONS Under the conditions of this study, saliva and serum conditioning of GP points plays an important role in the biofilm formation under tough environmental conditions.

Conclusion and Final Remarks

This final chapter is intended to summarize the main ideas of this irrigation book and give a perpective into the future of root canal disinfection.