Pathogenesis of non-infection related inflammatory root resorption in permanent teeth: A narrative review.

BACKGROUND: The mechanism of action of root resorption in a permanent tooth can be classified as infection-related (e.g., microbial infection) or non-infection-related (e.g., sterile damage). Infection induced root resorption occurs due to bacterial invasion. Non-infection-related root resorption stimulates the immune system through a different mechanism. OBJECTIVES: The aim of this narrative review is to describe the pathophysiologic process of non-infection-related inflammatory processes involved in root resorption of permanent teeth. METHODS: A literature search on root resorption was conducted using Scopus (PubMed and Medline) and Google Scholar databases to highlight the pathophysiology of bone and root resorption in non-infection-related situations. The search included key words covering the relevant category. It included in vitro and in vivo studies, systematic reviews, case series, reviews, and textbooks in English. Conference proceedings, lectures and letters to the editor were excluded. RESULTS: Three types of root resorption are related to the non-infection mechanism of action, which includes surface resorption due to either trauma or excessive orthodontic forces, external replacement resorption and external cervical resorption. The triggers are usually damage associated molecular patterns and hypoxia conditions. During this phase macrophages and clastic cells act to eliminate the damaged tissue and bone, eventually enabling root resorption and bone repair as part of wound healing. DISCUSSION: The resorption of the root occurs during the inflammatory phase of wound healing. In this phase, damaged tissues are recognized by macrophages and neutrophiles that secrete interlaukines such as TNF-α, IL-1, IL-6, IL-8. Together with the hypoxia condition that accelarates the secretion of growth factors, the repair of the damaged perioduntiom, including damaged bone, is initiated. If the precementum and cementoblast are injured, root resorption can occur. CONCLUSIONS: Wound healing exhibits different patterns of action that involves immune stimulation in a bio-physiological activity, that occurs in the proper sequence, with overlapping phases. Two pathologic conditions, DAMPs and hypoxia, can activate the immune cells including clastic cells, eliminating damaged tissue and bone. Under certain conditions, root resorption occurs as a side effect.

Development and Reversal of Discolouration in Roots Filled with Ledermix or Doxymix Pastes Stored in the Dark for Three Months then Daylight for Twenty Four Months.

OBJECTIVE: To explore the long-term effects on discolouration by demeclocycline HCl (Ledermix, LED) or doxycycline hyclate (Doxymix, DOX) pastes placed in extracted human teeth over a 27-month period under different storage conditions. METHODS: The canals in 38 teeth were prepared carefully, to minimize exposure to contamination from irrigants, then either LED (Lederle Pharmaceuticals, Germany) or DOX (Ozdent, Australia) were placed. Samples were stored in the dark for 3 months followed by daylight for 24 months. The storage conditions varied as follows: Group 1: Open access, dry storage (OD); Group 2: Closed access, dry storage (CD); Group 3: Open access, wet storage (OW); Group 4: Closed access, wet storage (n=4 for each material). Additional teeth were used as controls: Polyethylene glycol only in a closed canal; and saline only irrigation with LED paste in a closed canal. Standardised digital photographs were taken over 27 months and evaluated for changes in luminosity. RESULTS: Darkening of tooth structure occurred in all LED groups and in the two DOX groups that were stored wet, during exposure to light, with a faster rate with LED. The most rapid staining occurred with LED in moist conditions with an open access cavity. The least staining occurred with DOX in samples stored dry. With prolonged exposure to light, a reversal in staining occurred with DOX at 3 months and LED at 9 months. CONCLUSION: Staining of tooth structure is influenced by the choice of medicament, and by exposure to moisture and air. Light has a bimodal effect, first driving staining, but later reversing it. This can be explained by different wavelengths of light causing photodegradation and photo-oxidation of tetracyclines and their complexes with tooth mineral.

Active Bacteria in Carious Dentin of Mandibular Molars with Different Pulp Conditions: An In Vivo Study.

INTRODUCTION: This study evaluated the relative abundance and ribosomal activity of selected bacteria in carious dentin of teeth with different pulp conditions. METHODS: Thirty healthy patients with class I occlusal caries in molars were categorized into 3 groups based on the pulp diagnosis: normal pulp (NP, n = 10) with caries extending less than half the thickness of dentin (as assessed radiographically), reversible pulpitis (n = 10), and symptomatic irreversible pulpitis (n = 10) with caries extending more than two thirds of the thickness of dentin. Carious dentin samples were collected from the deepest part of the cavity and stored in RNAlater solution (Ambion Inc, Austin, TX). Eight bacterial taxa were evaluated from the samples: Streptococcus mutans, Lactobacillus fermentum, Veillonella, Actinomyces, Rothia dentocariosa, Olsenella profusa, Prevotella intermedia, and Bifidobacterium dentium. The 16S ribosomal RNA (rRNA) gene and 16S rRNA were quantified by real-time polymerase chain reaction and used to calculate the relative genome abundance and relative ribosomal abundance. The Fisher exact test was used to compare proportions between groups. The mean rank difference between the various groups was assessed using the Kruskal-Wallis test with the Bonferroni-Holm correction. RESULTS: The reversible pulpitis group had significantly higher 16S rRNA gene and rRNA counts of Actinomyces (P < .001 and P = .002) and B. dentium (P = .005 and P = .007) relative to the NP group. The symptomatic irreversible pulpitis group had significantly higher 16S rRNA gene and rRNA counts of L. fermentum (P < .001 and P < .001), Actinomyces (P < .001 and P < .001), O. profusa (P < .001 and P < .001), P. intermedia (P = .001 and P = .002), and Bifidobacterium (P < .001 and P < .001) relative to the NP group. CONCLUSIONS: Specific bacterial activity varies in carious dentin of teeth with different pulp conditions.

Coronal Bacterial Penetration after 7 days in class II endodontic access cavities restored with two temporary restorations: A Randomised Clinical Trial.

The aim of this in vivo randomised clinical trial was to assess coronal bacterial penetration after placement of Cavit G and IRM temporary restorations in Class II endodontic access cavities. After completion of endodontic treatment, placement of an orifice seal and disinfection of the operating field, sterile cotton pellets were placed in the pulp chamber and the cavities were restored with Cavit G or IRM. After 7 days, coronal and proximal restoration thickness was measured by digital radiographs. Cotton pellet was evaluated by culture methods and polymerase chain reaction assay and bacterial species identified. Bacterial growth was observed in 5 of the 27 (18%) Cavit G samples and in 11 of the 27 (40%) IRM samples which was not significant. Coronal restoration thickness of 4-5 mm and proximal restoration thickness of more than 2.15 mm for Cavit G and 2.35 mm for IRM are recommended to prevent bacterial penetration over 7 days. Adequate restoration thickness is critical to prevent bacterial penetration.

Evaluation of Dentin Defect Formation during Retreatment with Hand and Rotary Instruments: A Micro-CT Study.

The purpose of this study was to compare the incidence and longitudinal propagation of dentin defects after gutta-percha removal with hand and rotary instruments using microcomputed tomography. Twenty mandibular incisors were prepared using the balanced-force technique and scanned in a 19.9 µm resolution. Following filling with the lateral compaction technique, gutta-percha was removed with ProTaper Universal Retreatment (PTUR) or hand instruments. After rescanning, a total of 24,120 cross-sectional images were analyzed. The numbers, types, and longitudinal length changes of defects were recorded. Defects were observed in 36.90% of the cross sections. A total of 73 defects were comprised of 87.67% craze lines, 2.73% partial cracks, and 9.58% fractures. No significant difference in terms of new defect formation was detected between the retreatment groups. The apical and middle portions of the roots had more dentin defects than the coronal portions. Defects in three roots of the PTUR instrument group increased in length. Under the conditions of this in vitro study, gutta-percha removal seemed to not increase the incidence of dentin defect formation, but the longitudinal defect propagation finding suggests possible cumulative dentinal damage due to additional endodontic procedures. Hand and rotary instrumentation techniques caused similar dentin defect formation during root canal retreatment.

Antimicrobial and Cytotoxic Activity of Cinnamomum zeylanicum, Calcium Hydroxide, and Triple Antibiotic Paste as Root Canal Dressing Materials.

OBJECTIVE: The aim of this article was (i) to define the chemical constituents of Cinnamomum zeylanicum essential oil (CEO), (ii) to compare the antimicrobial activity of CEO with triple antibiotic paste (TAP) and calcium hydroxide [Ca(OH)2] on planktonic and biofilm Enterococcus faecalis; and (iii) to compare the cytotoxicity of these medicaments on L929 fibroblasts. MATERIALS AND METHODS: Gas chromatography-mass spectrometry was used to define the constituents of CEO. Zone of inhibition, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-kill tests were performed. Further, 108 human teeth were infected with E. faecalis and treated with the medicaments for 1, 7, and 14 days. Cytotoxicity was assessed by exposing L929 fibroblasts to the medicaments. RESULTS: Cinnamaldehyde was the main component of CEO. Triple antibiotic paste had the greatest zone of inhibition and the smallest MIC and MBC. Triple antibiotic paste and CEO eradicated planktonic E. faecalis after 4 and 24 hours, while Ca(OH)2 failed to achieve 100% killing after 24 hours. Cinnamomum zeylanicum essential oil and TAP eradicated biofilm E. faecalis after 7 and 14 days, but Ca(OH)2 could not eliminate E. faecalis after 14 days. Cinnamomum zeylanicum essential oil was the most biocompatible medicament. CONCLUSION: Cinnamomum zeylanicum essential oil is an efficient antibacterial agent against planktonic and biofilm E. faecalis and it was cytocompatible to L929 fibroblasts. Therefore, CEO has the potential to be used as an antimicrobial agent in root canal treatment.

Time-dependent antibacterial effects of Aloe vera and Zataria multiflora plant essential oils compared to calcium hydroxide in teeth infected with Enterococcus faecalis.

AIM: In the present in vitro study, we investigated the time-related antimicrobial efficacy of Aloe vera and Zataria multiflora (Z. multiflora) plant essential oils compared to calcium hydroxide ([Ca[OH]2 ) to eliminate Enterococcus faecalis (E. faecalis) from root canals. METHODS: A new strain of E. faecalis (Enterococcus spp. AGH04) was isolated from a previously root-filled tooth with persistent apical periodontitis. The 16S rRNA sequence was analyzed and deposited in GeneBank under accession number KF465681. A total of 108 extracted human single-rooted teeth were contaminated with this bacterial strain and treated with Aloe vera essential oil, Z. multiflora essential oil, and Ca(OH)2 for 1, 7, and 14 days. Gas chromatography-mass spectrometry (GC-MS) was used to determine the chemical composition of the oils. The percentage reduction from initial c.f.u./mL counts were calculated and analyzed. RESULTS: Carvacrol, thymol, and linalool were the main constituents of both essential oils. The c.f.u./mL count reductions significantly increased for all three medicaments when the contact time was extended. A statistically-significant difference was observed between the medicaments after 1 and 7 days, but there was no significant difference after 14 days. CONCLUSIONS: Both medicinal herbs showed equal antimicrobial efficiency against E. faecalis, comparable to Ca(OH)2 for the prolonged contact time of 14 days.

Effects of KTP Laser Bleaching on Traumatized Tooth Enamel.

BACKGROUND: Bleaching of traumatized discolored teeth is considered an important issue in esthetic dentistry. Various methods have been introduced for bleaching, some of which may have adverse effects on soft or hard tissues of the tooth. OBJECTIVES: The objective of the study was to evaluate the effects of KTP laser bleaching on enamel of traumatized teeth. MATERIALS AND METHODS: A square of 36 mm(2) was chosen on the labial surface of 32 extracted teeth. The corners were drilled in order to indicate the location precisely. The shade of each sample was recorded and the teeth were divided into four groups, each with eight teeth: group A (Smartbleach with KTP laser for 30 seconds), group B (Smartbleach with G-Light for 5 minutes), group C (only Smartbleach for 10 minutes) and group D (control group with no bleaching). After one session of bleaching, shade assessment was performed again. In another experiment on nine teeth, Smartbleach with KTP laser was used for 150 seconds to 1500 seconds. The samples were critically processed and observed by using scanning electron microscope (SEM) to assess enamel damage. Data was statistically analyzed using Kruskal-Wallis test (confidence interval level were set at 95%). RESULTS: Smartbleach was highly effective when used with KTP laser (P = 0.0419). Enamel damage was observed after frequent KTP bleaching and 750 seconds of KTP bleaching was recognized as the limit by morphological evaluation via SEM, indicating a major difference between under and over 750 seconds of bleaching. CONCLUSIONS: Application of KTP laser may increase the bleaching effect of Smartbleach, nevertheless it may cause some enamel damage.

Effect of occlusal reduction on postoperative pain in teeth with irreversible pulpitis and mild tenderness to percussion.

INTRODUCTION: Pain management after root canal treatment is a very important issue in clinical practice. The purpose of this study was to evaluate the effect of occlusal reduction on postoperative pain in teeth with irreversible pulpitis and tenderness to percussion. METHODS: Fifty-four posterior vital teeth with sensitivity to percussion requiring endodontic treatment were included in this study. After administration of local anesthesia, the root canals were instrumented, and an intracanal calcium hydroxide dressing was placed. The patients were randomly divided into 2 groups of 27 each. In 1 group the occlusal surface was reduced (OR group), whereas in the other group the occlusal surface was not modified (no occlusal reduction, NOR group). Each patient was asked to record their postoperative pain on a visual analogue scale with 4 categories at 6 hours, 12 hours, 18 hours, 1 day, and then daily for 6 days after this treatment. Data were analyzed by t test, Cochran Q, χ(2), and Mann-Whitney tests. RESULTS: Forty-six patients returned the visual analogue scale forms. There was no significant difference in postoperative pain between the 2 groups (P > .05) after root canal preparation and calcium hydroxide dressing. CONCLUSIONS: Occlusal surface reduction did not provide any further reduction in postoperative pain for teeth with irreversible pulpitis and mild tenderness to percussion compared with no occlusal reduction.

Comparison of the effect of various irrigants on apically extruded debris after root canal preparation.

INTRODUCTION: Several factors can influence the amount of apically extruded debris. The aim was to quantitatively compare the amount of debris extruded apically from root canals when 3 different irrigants were used during canal preparation with rotary instruments. METHODS: Ninety-one extracted single-rooted human mandibular premolar teeth with straight root canals were used. The teeth were randomly divided into 1 control group (group 1, n = 4) and 3 experimental groups of 29 teeth each. Hero 642 instruments were used for root canal preparation in all teeth, and 3 different irrigants were used (group 2, 2% chlorhexidine; group 3, 5.25% sodium hypochlorite; group 4, 2.5% sodium hypochlorite). Seven Eppendorf tubes served as a second control group. Debris extruded from the apical foramen during root canal preparation was collected into preweighed Eppendorf tubes. The weight of the dry extruded debris was established by subtracting the preinstrumentation and postinstrumentation weight of the Eppendorf tubes for each group. The data obtained were analyzed by using one-way analysis of variance and Tukey honestly significant difference. RESULTS: Group 3 (sodium hypochlorite 5.25%) had the highest amount of extruded debris, which was significantly different from the other groups (P < .05). CONCLUSIONS: The type of irrigant used can affect the amount of apically extruded debris. The 5.25% solution of sodium hypochlorite had the greatest amount of debris.