Histologic Response of Human Pulp and Periapical Tissues to Tricalcium Silicate-based Materials: A Series of Successfully Treated Cases

Pulpal/periapical responses of human teeth that are treated successfully with tricalcium silicate-based materials are extremely difficult to obtain because of the typical unavailability of these teeth for histologic examination. The present case series reports histologic and histobacteriologic findings of 3 human teeth that had undergone pulpotomy, orthograde retreatment, and apicoectomy/root-end filling using tricalcium silicate-based endodontic materials. The teeth were extracted after 34 days, 7 weeks, and 20 months, respectively, because of unusual circumstances. The extracted teeth were processed, paraffin embedded, sectioned, stained with hematoxylin-eosin or the modified Brown and Brenn technique, and examined with light microscopy. The recurrent observation for the 3 cases presented was the absence of inflammatory or foreign body reactions of the host tissues in contact with tricalcium silicate-based materials after different observation periods despite the identification of bacteria in dentinal tubules close to the site of operation. Wound healing was rapid with repair/regeneration of lost tissues with cementum and new bone trabeculae. Although the level of evidence for a case series is low because of the anecdotal nature of the reported episodes, the histologic results reported in the present case series illustrate the highly biocompatible and bioactive nature of the tricalcium silicate-based materials used in treating these cases.

Bioactive tri/dicalcium silicate cements for treatment of pulpal and periapical tissues

Over 2500 articles and 200 reviews have been published on the bioactive tri/dicalcium silicate dental materials. The indications have expanded since their introduction in the 1990s from endodontic restorative and pulpal treatments to endodontic sealing and obturation. Bioactive ceramics, based on tri/dicalcium silicate cements, are now an indispensable part of the contemporary dental armamentarium for specialists including endodontists, pediatric dentists, oral surgeons andfor general dentists. This review emphasizes research on how these materials have conformed to international standards for dental materials ranging from biocompatibility (ISO 7405) to conformance as root canal sealers (ISO 6876). Potential future developments of alternative hydraulic materials were included. This review provides accurate materials science information on these important materials. STATEMENT OF SIGNIFICANCE: The broadening indications and the proliferation of tri/dicalcium silicate-based products make this relatively new dental material important for all dentists and biomaterials scientists. Presenting the variations in compositions, properties, indications and clinical performance enable clinicians to choose the material most suitable for their cases. Researchers may expand their bioactive investigations to further validate and improve materials and outcomes.

[Accidental injection sodium hypochlorite during endodontic therapy. Better understand to better manage]

The high frequency of iatrogenic incidents during endodontic treatment is a source of stress for the practitioner. These incidents may occur during the different steps of a root canal treatment. During irrigation, extrusion of sodium hypochlorite beyond the apex is a rare but impressive accident. Sodium hypochlorite, is the most common irrigant used in modern endodontics, but when it comes in contact with the periapical tissue, it can cause complications ranging from mild discomfort to serious tissue damage such as the hematoma and hemato-emphysema. The aims of this article are to discuss through the presentation of two clinical cases: Etiological and predisposing factors; Signs guiding to suspicion of accidental injection of sodium hypochlorite. In this work, we focused on clinical keys that help the practitioner in better understanding this accident in order to prevent it or to manage it well when it occurs.

Healing after root-end microsurgery by using mineral trioxide aggregate and a new calcium silicate-based bioceramic material as root-end filling materials in dogs

INTRODUCTION

The purpose of this study was to compare healing after root-end surgery by using grey mineral trioxide aggregate (MTA) and EndoSequence Root Repair Material (RRM) as root-end filling material in an animal model.

METHODS

Apical periodontitis was induced in 55 mandibular premolars of 4 healthy beagle dogs. After 6 weeks, root-end surgeries were performed by using modern microsurgical techniques. Two different root-end filling materials were used, grey MTA and RRM. Six months after surgery, healing of the periapical area was assessed by periapical radiographs, cone-beam computed tomography (CBCT), micro computed tomography (CT), and histology.

RESULTS

Minimal or no inflammatory response was observed in the majority of periapical areas regardless of the material. The degree of inflammatory infiltration and cortical plate healing were not significantly different between the 2 materials. However, a significantly greater root-end surface area was covered by cementum-like, periodontal ligament-like tissue, and bone in RRM group than in MTA group. When evaluating with periapical radiographs, complete healing rate in RRM and MTA groups was 92.6% and 75%, respectively, and the difference was not statistically significant (P = .073). However, on CBCT and micro CT images, RRM group demonstrated significantly superior healing on the resected root-end surface and in the periapical area (P = .000 to .027).

CONCLUSIONS

Like MTA, RRM is a biocompatible material with good sealing ability. However, in this animal model RRM achieved a better tissue healing response adjacent to the resected root-end surface histologically. The superior healing tendency associated with RRM could be detected by CBCT and micro CT but not periapical radiography.

Management of sodium hypochlorite extrusion beyond the root apex during root canal treatment: a case report

Sodium hypochlorite (NaOCl) is most commonly used as an irrigating solution in endodontic practice. This paper describes an incident of sodium hypochlorite extrusion past the apex (SHEPA) of the UR3. Management of the condition resulted in hospitalisation of the patient, and intravenous antibiotic and steroid therapy. This case report details the measures that can be employed to reduce the risk of SHEPA and management of its potentially serious complications. The reader should understand the various measures that can be adopted to reduce extrusion of endodontic irrigants beyond the root apex and management following SHEPA.

Oral tissue complications during endodontic irrigation: literature review

The literature concerning the etiology, symptomatology and management of complications during root canal irrigation is reviewed. Clinical symptoms are discussed, as well as preventive and therapeutic considerations.

[General and local factors affecting periapical reparation after endodontic procedures]

Eighty-seven teeth with 100 periapical destruction foci have been treated in 78 patients from 19 to 60 years of age. In 28 patients calcium-containing preparation was administrated orally for 1 to 3 months. The dynamics of destruction foci changes was similar in all patients though among patients with satisfactory X-ray findings 64% took calcium-containing preparation. No considerable difference in the regeneration dynamics was revealed in patients with somatic diseases and healthy individuals. The residual destruction size 12 months later correlated positively with the initial size of destruction area.

Root canal complications: 'the hypochlorite accident'

Root canal treatment is performed routinely in dental practice, using sodium hypochlorite which serves as an effective irrigant. The literature reviewed shows that several complications following irrigation with sodium hypochlorite may occur, but few practitioners are aware of it and its management. Such complications include injury to skin, oral mucosa and eyes, damage to clothing, air emphysema, allergic reactions, and injection beyond the foramen. In this article, a case report of injection with sodium hypochlorite beyond the foramen is presented, together with a review of the recent literature regarding common manifestations and case histories. The literature shows no standard management of this condition, but symptomatic therapies are discussed. It is important to minimize the risk of sodium-hypochlorite-induced damage during root canal therapy by use of protective measures, appropriate instrumentation and techniques, and consider alternate irrigation solutions.

Resin materials for root canal obturation

With the appearance of more in vivo and ex vivo publications, methacrylate based resin sealers are becoming more popular in endodontics. Their ease of use and favorable clinical performance offer an attractive alternative to conventional endodontics. This article reviews the development of resin-based sealers and biocompatibility tests. The many, mostly opposing views are analyzed to put what has been published thus far in perspective. A critical analysis of the facts leads to the consensus that methacrylate based resin sealers are here to stay and offer a suitable alternative to conventional endodontic treatment.

Cellular response to mineral trioxide aggregate root-end filling materials

Endodontic surgical procedures involve the use of a root-end filling material to provide an apical seal and to facilitate the repair and regeneration of periradicular tissues. Whereas earlier studies typically evaluated the cytotoxicity of these materials, contemporary research has focused on their capacity to support a favourable cellular response. In vitro tissue culture techniques have demonstrated interactions at the cell surface that may be conducive to periapical healing. Recent research with osteoblasts has confirmed their affinity for novel endodontic mineral trioxide aggregate (MTA) materials, with evidence of cell attachment and synthesis of bone matrix. This article reviews the current state of knowledge about MTA as a root-end filling material, with particular emphasis on cellular response to MTA materials.

Tissue damage after sodium hypochlorite extrusion during root canal treatment

Sodium hypochlorite solution is toxic to vital tissues, causing severe effects if extruded during endodontic treatment. This paper presents a report on the tissue damage related to inadvertent extrusion of concentrated sodium hypochlorite solution during root canal treatment. A 65-year-old woman was referred with moderate pain, ecchymosis, and severe swelling of the right side of the face. These symptoms appeared immediately after a root canal treatment of the maxillary right canine, which had been started 21 hours earlier. It was diagnosed as air emphysema related to sodium hypochlorite solution extravasation during the endodontic treatment. To avoid this, an initial radiograph should be taken to determine the correct canal working length and confirm root canal integrity.

Unusual case of adverse reaction in the use of sodium hypochlorite during endodontic treatment: a case report

Sodium hypochlorite (NaOCl) is currently used in the debridement and disinfection of the root canal system, supporting the mechanical procedures. Although it is considered a safe irrigant, the literature reports a few cases of adverse reaction caused by NaOCl: They range from injection through the apical foramen to air emphysema and allergic reactions as complications during endodontic treatment. The present report shows the possible severe clinical consequences of concentrated NaOCl extruding through the periapical tissues during root canal irrigation in a patient not allergic to NaOCl.

Sodium hypochlorite chemical burn. Case report

Sodium hypochlorite (NaOCl) is a well documented and widely accepted intracanal irrigant used to disinfect the pulp space in endodontic therapy. NaOCl can be an extremely cytotoxic material; therefore, care must be taken with its use. The authors present a case of periradicular extravasation of NaOCl with sequelae of pain, swelling, ecchymosis and parasthesia consistent with a chemical burn. The patient was treated with a nonsurgical medical management approach. She experienced a complete resolution of signs and symptoms, aside from a persistent residual focal parasthesia.

Benefits of additional courses of systemic azithromycin in periodontal disease case report

The strong association of subgingival anaerobic bacteria, such as Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia, with destructive periodontal disease has been well documented in the literature. Several double-blind studies have also shown the beneficial use of systemic antimicrobials that are active against these microorganisms in conjunction with conventional periodontal treatment, especially when periodontal abscesses and/or suppuration upon probing are present. Four cases with periodontal abscesses were treated with scaling/root planing in conjunction with systemic azithromycin. Partial improvement led to retreatment with two additional courses of azithromycin. Bone formation was noted on periapical radiographs after the patients took additional courses of azithromycin. In view of the benefits of using additional courses of azithromycin in the treatment of destructive periodontal disease, we conclude that the single course of systemic antimicrobials currently used in periodontal therapy may be insufficient to reach necessary therapeutic levels in infected sites.

Pulpal and periapical response of dogs' teeth after pulpotomy and use of recombinant human bone morphogenetic protein-7 as a capping agent

OBJECTIVE

The purpose of this study was to evaluate the pulpal and periapical response of dogs' teeth after pulpotomy and the use of recombinant human bone morphogenetic protein-7 as a capping agent.

METHODS

Pulpotomy was performed in 60 teeth from 6 dogs, and the remaining pulp tissue was capped with the following materials: (a) groups 1 and 5: recombinant human bone morphogenetic protein-7 associated with recombinant human-like collagen; (b) groups 2 and 6: recombinant human-like collagen; (c) groups 3 and 7: calcium hydroxide; and (d) groups 4 and 8: zinc oxide and eugenol cement. After 7 days (groups 1-4) and 70 days (groups 5-8), the animals were sacrificed and the pieces containing the teeth were removed and processed for histological analysis.

RESULTS

Seven-day period: according to the type of inflammatory infiltrate observed in the root pulp tissue: (a) groups 1 and 2 were classified as severe with intense vascular proliferation; (b) group 4 was classified as moderate; and (c) group 3 was classified as mild. No dentin bridge formation was observed in any specimen, and the periapical region had normal appearance. 70-day period: groups 5, 6, and 8 showed no dentin bridge formation, and the remaining pulp tissue presented necrotic areas with inflammatory cells in the periapical region as well as bone and cemental resorption. In group 7, there was dentin bridge formation, absence of inflammation, and absence of mineralized tissue resorption.

CONCLUSION

The use of rHuBMP-7/rHuCollagen as a capping material after pulpotomy did not show either satisfactory apical and periapical response or capacity of inducing deposition of mineralized tissue.

Mineral trioxide aggregate: a review of the constituents and biological properties of the material

This paper reviews the literature on the constituents and biocompatibility of mineral trioxide aggregate (MTA). A Medline search was conducted. The first publication on the material was in November 1993. The Medline search identified 206 papers published from November 1993 to August 2005. Specific searches on constituents and biocompatibility of mineral trioxide aggregate, however, yielded few publications. Initially all abstracts were read to identify which fitted one of the two categories required for this review, constituents or biocompatibility. Based on this assessment and a review of the papers, 13 were included in the constituent category and 53 in the biocompatibility category. Relatively few articles addressed the constituents of MTA, whilst cytological evaluation was the most widely used biocompatibility test.

Histologic evaluation of periradicular tissues in dogs treated with calcium hydroxide in combination with HCT20 and camphorated P-chlorophenol

OBJECTIVE

The aim of this study was to evaluate the biocompatibility of calcium hydroxide suspended in HTC20 or calcium hydroxide plus CMCP and their effects on the healing of periapical lesions in dogs.

STUDY DESIGN

Experimental apical periodontitis was induced by opening the pulp chamber of 36 mandibular premolars in 6 3-year old dogs. The teeth were left opened for 1 week and then closed with IRM for 60 days in order to induce periapical lesions. The teeth were divided into 1 control and 2 experimental groups. Both experimental groups received intracanal dressings with a calcium hydroxide slurry. In the first experimental group calcium hydroxide was mixed with a detergent vehicle and in the second group with camphorated parachlorophenol. The medications were kept in the root canal for 2 periods of 30 days each. Afterwards, the dogs were killed and the periapical areas were studied histologically.

RESULTS

Based on biocompatibility and tissue remodeling in the periapical area, the best results were observed when calcium hydroxide was mixed with the detergent. The difference was statistically significant (P < .05).

CONCLUSION

Calcium hydroxide plus CMCP intracanal dressing was the most irritating to the periapical region, and the group of calcium hydroxide plus HCT 20 showed the best results whenever biocompatibility and the capacity of new bone formation was considered.

Histologic study of furcation perforations treated with MTA or Super EBA in dogs' teeth

OBJECTIVE

The aim of this study was to investigate the histologic response to MTA or Super EBA when used for the repair of furcation perforations in dogs' teeth.

STUDY DESIGN

Ninety mandibular premolar and molar teeth of 9 mongrel dogs were used in this study. The teeth were divided into 3 groups. Seventy-two teeth were repaired with either MTA or Super EBA (36 each), and 18 teeth were not repaired and used as negative controls. All groups were histologically examined at 1 month, 3 months, and 6 months after treatment. Histologic evaluation was done with regard to inflammation and type of healing.

RESULTS

The Super EBA group showed moderate inflammation in 1 month; the inflammation decreased over time, but most of specimens showed inflammatory reaction from mild to severe at the end of 6 months. The perforation area was filled by connective tissue in specimens in which no inflammation was seen. In the MTA group, mild inflammation was seen in 1 month, it decreased in 3 months, and no inflammation was detected in 6 months. New cementum formation was taken in place in 4 specimens in 1 month, in 8 specimens in 3 months, and in all specimens in 6 months.

CONCLUSIONS

MTA showed less inflammation than Super EBA. MTA specimens showed healing with new cementum formation in the perforation area, whereas Super EBA specimens in which no inflammation was seen showed connective tissue healing.

Biologic perspectives to support clinical choices in root canal treatment

Some of the most keenly debated issues in endodontics have revolved around the where to end the root filling, as well as cleaning and shaping and obturation techniques. In some respects, original scientifically-based concepts have been abandoned in favour of clinical techniques that may provide aesthetically pleasing radiographs, but do not necessarily support tissue regeneration around the root apex following obturation. Recently advocated obturation techniques supporting the use of resin-based and bonded materials have not had the same extensive evaluation that gutta-percha, when in contact with the periradicular tissues, has had. Further studies are necessary so that evidence-based data can support the confident use of these innovative materials.

[Animal test of nHA-PA66 used in root canal filling]

OBJECTIVE

To assess the dogs' tissue reaction to nHA-PA66 which is prepared to be used as a new root canal filling sealer.

METHODS

The experimental apical periodontitis of dogs was induced first, then nHA-PA66 was used in the test groups while CCQ was used in the control group. The reactions of periapical tissues were measured by histological means.

RESULTS

One month after nHA-PA66 was used in root canal filling, the dogs' periapical tissues showed mild to moderate inflammatory reactions, the X-ray films showed decreased radiolucent area as compared with the previous film. Three months later, tissue repairs occurred, which exhibited even more decreased radiolucent area on X-ray films. nHA-PA66 caused weak inflammatory reaction while the reparative reaction happened early.

CONCLUSION

nHA-PA66 has good tissue compatibility and is a potential sealer for root filling in clinical use.

Effectiveness of Sodium Hypochlorite in Preventing Inoculation of Periapical Tissues With Contaminated Patency Files

The aim of this study was to analyze the effectiveness of 5.25% sodium hypochlorite (NaOCI) in preventing inoculation of periapical tissues with contaminated patency files. Twenty-eight extracted human permanent teeth with single canals were used in the study. Group I teeth were filled with NaOCl, and #15 stainless steel files contaminated with Streptococcus sanguis (ATCC #10556) were allowed to pass through the NaOCI into the culture medium. The teeth in group II were also filled with NaOCl, but the contaminated files used in group II canals were immersed in NaOCl for 10 s prior to being placed into the canals and cultured. The negative control group used sterile files (0% growth), the first positive control group used contaminated patency files in teeth with empty canals (100% growth), and the second positive control group placed contaminated files into broth next to teeth filled with NaOCl (to evaluate potential chlorine leakage; 100% growth). The experimental results showed no positive growth of S. sanguis for groups I and II, indicating that the NaOCl present in the canal after irrigation was sufficient to kill the test organism.

Histological study of the effect of some irrigating solutions on bacterial endotoxin in dogs

The aim of this study was to evaluate, histopathologically, the effectiveness of mechanical preparation of root canals using different irrigating solutions in dog teeth filled with LPS after pulpectomy. A total of 120 root canals of 6 mongrel dogs were filled with a solution of LPS after pulpectomy. The irrigating solutions used were saline, 1, 2.5, and 5% sodium hypochlorite, and 2% chlorhexidine. No irrigation was used in the control group. The animals were sacrificed after 60 days and the teeth were fixed and demineralized. Subsequently, serial 6-µm sections were stained with hematoxylin and eosin and Mallory's trichrome for histopathological analysis and Brown-Brenn for verification of bacterial contamination. Analysis showed that the inflammatory infiltrate was statistically less intense in the groups in which the root canals were irrigated with 5% sodium hypochlorite and 2% chlorhexidine. However, none of the irrigating solutions completely inactivated the harmful effects of LPS. Mechanical preparation associated with different irrigating solutions did not completely inactivate LPS.

[Accidental extrusion of calcium hydroxide-based pastes into periapical lesions]

Calcium hydroxide is a widely used material in endodontic treatment due to its high alkalinity and antimicrobial properties. It is thought to create a favourable environment for periradicular repair and healing, and to stimulate hard tissue formation. The aim of the present retrospective study was to evaluate the effect of accidental and voluminous overextensions of calcium hydroxide pastes into periapical lesions and tissues on the prognosis of periapical healing. It was seen that calcium hydroxide overextensions did not disfavour healing, none of the endodontic treatments failed but healing was delayed in the majority of cases and in a number of cases extrusion induced immediate flare-ups. Therefore the deliberate extrusion of calcium hydroxide into periapical tissues is not advocated.

Biocompatibility of dental materials used in contemporary endodontic therapy: a review. Part 2. Root-canal-filling materials

Root-canal-filling materials are either placed directly onto vital periapical tissues or may leach through dentine. The tissue response to these materials therefore becomes important and may influence the outcome of endodontic treatment. This paper is a review of the biocompatibility of contemporary orthograde and retrograde root-canal-filling materials.

Biocompatibility of dental materials used in contemporary endodontic therapy: a review. Part 1. Intracanal drugs and substances

Irrigation solutions and intracanal medicaments are used within the root canal to clean and aid in disinfecting the dentinal walls. Although these materials are intended to be contained within the root canal, they invariably contact the periapical tissues, either through inadvertent extrusion through the apex or leaching. This paper is a review on the methodology involved in biocompatibility testing followed by a discussion on biocompatibility of contemporary intracanal drugs and substances used in endodontics.

Apical and periapical repair of dogs' teeth with periapical lesions after endodontic treatment with different root canal sealers

The aim of this study was to evaluate the apical and periapical repair after root canal treatment of dogs' teeth with pulp necrosis and chronic periapical lesion using different root canal sealers. After periapical lesion induction, forty-four root canals of 3 dogs were submitted to biomechanical preparation using 5.25% sodium hypochlorite as an irrigating solution. A calcium hydroxide dressing (Calen PMCC) was applied for 15 days and the root canals were filled using the lateral condensation technique with gutta-percha points and Sealapex, AH Plus or Sealer Plus for sealing. After 180 days, the animals were sacrificed by anesthetic overdose and the obtained histological sections were stained with hematoxylin-eosin for optical microscopic analysis of the apical and periapical repair. The groups filled with Sealapex and AH Plus had better histological repair (p < 0.05) than the group filled with Sealer Plus, that had unsatisfactory results.

Periapical lesions accidentally filled with calcium hydroxide

AIM

To evaluate the effect of accidental and voluminous calcium hydroxide overextensions into periradicular lesions and tissues on the prognosis of periapical healing.

SUMMARY

Eleven cases with periapical lesions and voluminous calcium hydroxide overextension are presented. Despite literature reports on the deleterious effects of calcium hydroxide extension in the periapical area, none of the endodontic treatments failed and surgical intervention was not indicated.

KEY LEARNING POINTS

Extensive extrusion of calcium hydroxide into the periapical tissues does not appear to comprise periapical healing. Despite this finding, the deliberate extrusion of dental materials into the apical tissues is not advocated.

Comparison of Diaket and MTA when used as root-end filling materials to support regeneration of the periradicular tissues

AIM

The objective of this study was to evaluate on a comparative basis the potential for mineral trioxide aggregate (MTA) and Diaket to promote periradicular tissue regeneration when used as surgical root-end filling materials.

METHODOLOGY

Seven dogs weighing between 15 and 25 kg were anesthetized prior to having the root canals of their mandibular premolars accessed, cleaned, shaped and obturated. Coronal access cavities were restored with IRM. Surgical access to the root ends was established and the root ends were resected and prepared with ultrasonic tips. Root-end fillings of either MTA or thickly mixed Diaket were randomly assigned to the preparations. Reflected tissues were repositioned and sutured with 4-0 vicryl sutures. Sixty days postsurgery, the animals were killed, perfused with 10% neutral buffered formalin and the third and fourth premolars removed in block sections. The specimens were demineralized and sectioned at 6-microm intervals for histological assessment. Sections were stained with either haematoxylin and eosin or Gomori's one step trichrome stain and examined under the light microscope. All evaluations were made by two calibrated examiners and gradings were scored based on established criteria. The raw data was evaluated statistically using anova after adjusting for the animal block effect.

RESULTS

Statistical evaluation indicated that there were no statistical differences between the observed regenerative responses of the tissues to the two root-end filling materials.

CONCLUSIONS

Both Diaket and MTA can support almost complete regeneration of the periradicular periodontium when used as root-end filling materials in periradicular surgery on noninfected teeth.

Calcium hydroxide root canal dressing. Histopathological evaluation of periapical repair at different time periods

The objective of this study was to evaluate periapical and apical repair using calcium hydroxide root canal dressings for different lengths of times in teeth with induced chronic periapical lesions. A total of 61 root canals of maxillary and mandibular premolars from 4 dogs were used. After mechanical preparation of the root canals using the crown-down technique, and 5.25% NaOCl as irrigating solution, the apical foramen was enlarged in all cases. A calcium hydroxide root canal dressing was applied. The control group did not receive a root canal dressing. The animals were killed at 7, 15 or 30 days. After histological preparation, serial sections were stained with hematoxylin-eosin and Mallory's trichrome. The best histopathological results occurred at 15 and 30 days, and the worst results occurred at 7 days and in the control group.

Effect of irrigating solution and calcium hydroxide root canal dressing on the repair of apical and periapical tissues of teeth with periapical lesion

The objective of this study was to evaluate the apical and periapical repair after endodontic treatment of teeth with pulp necrosis and a chronic periapical lesion in dogs. Seventy-two root canals from four mongrel dogs were submitted to biomechanical preparation, using 5.25% sodium hypochlorite or 2% chlorhexidine digluconate as the irrigating solution. The root canals were subsequently either filled immediately with Sealapex, using active lateral gutta-percha condensation, or a calcium hydroxide root canal dressing was applied for 15 days before filling with Sealapex. After 210 days, the animals were killed by anesthetic overdose, and the obtained histological sections were stained with hematoxylin and eosin for optical microscopic analysis of apical and periapical repair. There was better histological repair in the groups with the root canal dressing (p < 0.05) than the groups with immediate obturation. Comparing the immediate obturation groups, irrigation with chlorhexidine solution resulted in better repair than sodium hypochlorite.

Influence of root canal dressings and sealers on repair of apical periodontitis after endodontic treatment

OBJECTIVE

The objective of this study was to evaluate the histopathologic response of periapical tissues after root canal treatment of necrotic dog teeth with chronic apical periodontitis by using 2 calcium hydroxide-based root canal dressings and 2 root canal sealers.

STUDY DESIGN

Seventy-eight root canals were instrumented by using 5.25% sodium hypochlorite as the irrigating solution, after which a calcium hydroxide paste (Calen/PMCC or Calasept) was placed for 30 days as a dressing. The root canals were then filled by using cold lateral gutta-percha condensation and an endodontic sealer (Sealapex or AH Plus). After 360 days, the animals were killed by anesthetic overdose; then, the teeth were histologically prepared, sectioned, and stained with hematoxylin and eosin for optical microscopic analysis of apical and periapical tissue repair.

RESULTS

Statistical analysis showed that the poorest histopathologic results were observed in the Calasept/AH Plus group and that the Sealapex sealer overall resulted in better apical repair than the AH Plus sealer. The histopathologic results of Calen/PMCC paste with both AH Plus and Sealapex and Calasept paste with only Sealapex were statistically similar but were different from the results of Calasept with AH Plus.

CONCLUSIONS

The results of this study in the dog showed differences in apical and periapical tissue repair of teeth with chronic apical periodontitis by using 2 calcium hydroxide root canal dressings and 2 sealers. More research is necessary to determine the best combination of dressings and sealers.

Histological evaluation of electrosurgery and formocresol pulpotomy techniques in primary teeth in dogs

The purpose of this study was to compare pulpal and periapical tissue reactions to electrosurgery versus formocresol pulpotomy techniques in the primary teeth of dogs. The study was conducted on 33 primary teeth of three mongrel dogs between the ages of one to three months. Each dog had three teeth treated by Formocresol Pulpotomy with Mechanical Coronal Pulp Removal (FC), three teeth treated by Electrosurgery Pulpotomy with Mechanical Coronal Pulp Removal (ES/MCPR), three teeth treated by Electrosurgery Pulpotomy with Electrosurgical Coronal Pulp Removal (ES/ECPR), and two teeth serving as untreated Controls. Dogs one, two and three were sacrificed performing the pulpotomies at two, four and six weeks, respectively. The pulp, periapical tissue and after surrounding bone were submitted to histological examination and the histological reaction was recorded. The results were fourteen out of 18 unfavorable and zero out of three favorable histological reactions occurred in the FC treated teeth. Six out of 18 unfavorable and one out of three favorable histological reactions occurred in the ES/MCPR treated teeth. Nine out of 18 unfavorable and two out of three favorable histological reactions occurred in the ES/ECPR treated teeth. One out of 18 unfavorable and zero out of three favorable histological reactions occurred in the untreated Control teeth. The conclusion of this study is that of the three experimental groups, the teeth treated by Electrosurgery Pulpotomy with either Mechanical or Electrosurgical Coronal Pulp Removal exhibited less histopathological reaction than the teeth treated by Formocresol Pulpotomy.

Treatment protocol for the management of a sodium hypochlorite accident during endodontic therapy

During routine endodontic therapy, sodium hypochlorite inadvertently was forced out the apex of tooth No. 12. The patient experienced immediate severe pain, swelling, and hemorrhage from the canal access. Treatment was palliative, including patient education and reassurance, narcotic analgesics, cold and hot compresses, and multiple follow-up visits.

Cytotoxicity of halothane on human gingival fibroblast cultures in vitro

Recently halothane has been reported to be the most suitable alternative to chloroform in dissolving gutta-percha. Periapical tissue toxicity of halothane is not completely known. In this study gutta-percha dissolved by halothane was evaluated with the almar blue dye assay using human gingival fibroblast cultures. The cytotoxic effects of halothane on human gingival fibroblasts depended on the exposure dose, frequency, and duration. A reduced concentration and smaller amount of gutta-percha solvents may minimize the cytotoxic effects on host tissues.

Formation of a facial hematoma during endodontic therapy

BACKGROUND

Sodium hypochlorite, or NaOCl, is one of the most commonly used irrigating solutions in endodontic practice. Its clinically proven antibacterial, solvent and lubricating properties make it a very appealing choice as an intracanal medicament.

CASE DESCRIPTION

The authors present a case of facial hematoma formation after an inadvertent injection of NaOCl into the periapical tissues. The NaOCl solution caused extensive tissue destruction. Management of the condition required the hospitalization, intravenous antibiotic therapy and multiple intraoral surgical incisions to facilitate drainage.

CLINICAL IMPLICATIONS

Use of NaOCl must be confined to the root canal system. This report reviews this intracanal medicament's potential toxicity and emphasizes the need for clinicians to remain cognizant of possible problems while using the solution.

Reaction of dogs' teeth to root canal filling with mineral trioxide aggregate or a glass ionomer sealer

This study was conducted to observe the reaction of apical tissues of dogs' teeth after root canal filling with gutta-percha and mineral trioxide aggregate (MTA) or a glass ionomer (Ketac-Endo) as a sealer. The root canals were instrumented and filled by the lateral condensation technique with the sealers studied. Animals were killed 6 months later, and the specimens were removed and prepared for histological analysis. Results showed no inflammatory reaction of apical tissue and total closure of the apical foramen of all the teeth sealed with MTA. The teeth sealed with Ketac-Endo showed two cases of partial closure and different degrees of chronic inflammatory reaction. In conclusion, MTA exhibited better biological properties than Ketac-Endo.

Calcium hydroxide and a corticosteroid-antibiotic association as dressings in cases of biopulpectomy. A comparative study in dogs' teeth

The subject of this paper was to study the behavior of the periapical tissues of dogs' teeth after biopulpectomy and dressing with calcium hydroxide or a corticosteroid-antibiotic association, before root canal filling with zinc oxide eugenol (ZOE) or Sealapex sealers. The teeth were overinstrumented and dressed for 7 days before the root canal filling. The animals were sacrificed 180 days after treatment and the specimens were prepared for morphological analysis. Specimens treated with Sealapex presented a higher number of cases with biological closure than ZOE. When the root canals were filled with ZOE, better results were observed with the use of the Ca(OH)2 dressing.

Tissue response to an epoxy resin-based root canal sealer

The objective of the present study was to evaluate two different types of root canal sealers: AH Plus (an epoxy resin-based sealer) and Fill Canal (a zinc oxide-eugenol based sealer). A total of 34 root canals with vital pulp from dogs' premolars were used. After instrumentation, the root canals were filled with gutta-percha and AH Plus or gutta-percha and Fill Canal sealers using a classical technique of lateral condensation. After histological processing, the sections were stained with hematoxylineosin or Mallory's trichrome stain. Inflammatory cells or areas of necrosis were not associated with AH Plus. Hard tissue formation apically to the material was observed in 14 specimens. The Fill Canal sealer presented an inflammatory response of moderate intensity in the periapical region, mainly adjacent to the material.

Histological study of periapical tissue healing in the rat molar after retrofilling with various materials

We histologically examined the effects on the periapical tissue of various dental filling materials applied as retrofillings in rats and compared them with those of amalgam. The 4-META-TBB resin Superbond and the light-cured composite resin produced the least severe inflammatory reaction, with the greatest amount of new bone. In these specimens, regeneration of a part of the periodontal ligament was also observed. These results indicate that these materials might be very biocompatible and thus foster the natural regeneration of the periapical tissue.

Use of a hydroxylapatite-based material and calcium sulfate as artificial floors to repair furcal perforations

OBJECTIVE

The purpose of this study was to evaluate a hydroxylapatite-based material and calcium sulfate when each was used under a resin-modified glass ionomer cement to repair furcation perforations.

STUDY DESIGN

Perforations of pulp chamber floors were made in 72 teeth of 9 dogs. Perforations were divided into 3 equal-sized groups and repaired with resin-modified glass ionomer either alone or over an artificial floor. The artificial floor was either a hydroxylapatite-based material or calcium sulfate. Three dogs were killed at each of 3 intervals (1, 3, and 6 months). The tissue response to the tested materials was evaluated clinically, radiographically, and histologically.

RESULTS

The hydroxylapatite-based material showed the highest radiographic success; this was followed by calcium sulfate and glass ionomer. From histologic evaluation, the average success rate was found to be 67% for calcium sulfate, 62% for the hydroxylapatite-based material, and 59% for glass ionomer. However, there was no statistical significant difference with the resin-modified glass ionomer when it was used alone and when it was used over a barrier. There was also no significant difference between the hydroxylapatite-based material and the calcium sulfate when they were used as artificial floors.

CONCLUSION

The use of an artificial floor may not be necessary when flowable resin-modified glass ionomer cements are used.

Histological evaluation of the response of apical tissues to glass ionomer and zinc oxide-eugenol based sealers in dog teeth after root canal treatment

The object of the study was to compare two commercial root canal sealers: Ketac-Endo (a glass ionomer cement) and Fill Canal (a zinc oxide-eugenol cement). A total of 34 root canals from dog premolars with vital pulps were used. After instrumentation, the root canals were sealed with Ketac-Endo and Fill Canal cements using gutta-percha and a lateral condensation technique. After 270 days the animals were sacrificed with an anesthetic overdose and the maxillae and mandibles were removed and fixed in formalin for 48 h. After routine histological processing the sections were stained with hematoxylin-eosin and Mallory trichrome stains. Microscopic analysis revealed that Ketac-Endo cement presented better results than Fill Canal cement.

Inflammation-associated lysyl oxidase protein expression in vivo, and modulation by FGF-2 plus IGF-1

Lysyl oxidase is the extracellular enzyme that catalyzes oxidative deamination of peptidyl-lysine residues in elastin precursors, and lysine and hydroxylysine residues in collagen precursors to form peptidyl-aldehydes. These aldehydes then spontaneously condense to crosslink collagen and elastin and thereby allow the formation of a mature and functional extracellular matrix. In the present study, cryosections made from aseptic immune-induced periapical lesions experimentally generated in laboratory rats were examined by immunohistochemistry to investigate whether lysyl oxidase protein expression is altered in inflamed oral tissues. Periapical lesions are experimentally induced endodontic lesions of tooth roots. In addition, the effect of administration of a mixture of fibroblast growth factor (FGF)-2 and insulin-like growth factor (IGF)-1 into these lesions on lysyl oxidase expression was determined. Lysyl oxidase expression was found to be increased in non-mineralized connective tissue adjacent to inflamed lesions. Morphometric analyses indicated that maximum lysyl oxidase expression occurred at a discrete distance from the lesion not exceeding 350 microm from the inflammatory cells. Staining was associated with mesenchymal cells with a fibroblastic morphology. No lysyl oxidase staining was found near teeth where no lesion was induced. Application of a mixture of FGF-2 and IGF-1 resulted in a further twofold increase in lysyl oxidase expression. These results provide a new in vivo model to study lysyl oxidase regulation, and suggest that inflammatory cells may control lysyl oxidase expression in oral tissues, possibly by a mechanism involving secretion of cytokines and other factors, probably contributing to the regulation of extracellular matrix accumulation.

Use of calcium hydroxide for apical barrier formation and healing in non-vital immature permanent teeth: a review

OBJECTIVE

To review the use of calcium hydroxide for induction of apical barrier formation and healing in immature permanent teeth.

INTRODUCTION

Pulp necrosis is a frequent complication of dental trauma in immature permanent teeth. Endodontic treatment of these teeth is often complicated. The walls of the root canals are frequently divergent and the apices immature, making debridement and obturation difficult. The aim of treatment is induction of apical healing which may be defined as apical closure through formation of mineralised tissue and repair of the periapical tissues. Calcium hydroxide is the material of choice for apical barrier formation and healing.

RESULTS

The use of calcium hydroxide for apical barrier formation is successful in 74-100% of cases irrespective of the proprietary brand used. The average length of time for apical barrier formation is approximately 5 to 20 months. Control of infection and adequate cleaning of the root canal are very important for apical healing.

CONCLUSIONS

While the success rate of apical barrier formation using calcium hydroxide is high, long-term follow-up of these teeth is necessary. Problems such as failure to control infection, recurrence of infection and cervical root fracture may occur. The latter is more frequent in immature luxated teeth with the least root development.

A histological and quantitative histomorphometric study of apexification of nonvital permanent incisors of vervet monkeys after repeated root filling with a calcium hydroxide paste

The purpose of this study was to compare the effect of a monthly refilling of the root canals with calcium hydroxide paste with a single packing or replacement of the paste at 3 months on the apexification of nonvital maxillary incisors of vervet monkeys. Forty-eight maxillary incisors from 12 monkeys were used following radiographic determination that root development was incomplete. The pulps were extirpated under general anesthesia and the root canals filed and cleaned. The root canals were filled with a commercial calcium hydroxide paste, Calxyl, and a temporary cavity filling placed. Twelve teeth were left without further treatment. The calcium hydroxide paste was replaced in 12 teeth after a 3-month interval, and in the remaining 24 teeth the calcium hydroxide root filling was replaced five times at monthly intervals. The monkeys were killed after 6 months, and blocks of the teeth and surrounding tissues were embedded, decalcified and 6 microns serial sections prepared and stained. The sections were studied histologically to evaluate 11 parameters. Significant differences were found in the amount of calcium hydroxide at the apices, the presence of new cementum on the roots and the degree of inflammation, all of which were better in the monthly refill group. Histomorphometric measurements to evaluate the obturation of the open apices and the volume of new primary osteocementum showed no significant difference between the three groups. It was suggested that after the initial root filling with calcium hydroxide there was nothing to be gained by repeated root filling either monthly or after 3 months, for at least 6 months.

Calcium hydroxide root canal sealers--histopathologic evaluation of apical and periapical repair after endodontic treatment

Eighty root canals of the premolars of 4 dogs, with vital pulp, were instrumented and filled during the same session with the Sealapex, CRCS, Sealer 26, and Apexit sealers. The animals were sacrificed 180 days after root canal filling and their maxillae and mandibles were removed and fixed in 10% formalin. After routine histologic processing, the sections were stained with hematoxylin-eosin and Mallory trichrome. Histopathologic analysis showed that Sealapex was the sealer that best permitted the deposition of mineralized tissue at the apical level and was the only sealer that provided complete sealing (37.5% of cases). With the use of Sealapex, no inflammatory infiltrate occurred and there was no reabsorption of mineralized tissues. In contrast, partial sealing and a moderate inflammatory infiltrate occurred with the use of CRCS. When Apexit and Sealer 26 were used the absence of sealing was frequent and active reabsorption of mineralized tissues occurred in most cases. The inflammatory infiltrate predominating with the use of Apexit was of the severe type, whereas with the use of Sealer 26 the inflammatory infiltrate was mild or absent.

EDTA inhibits in vitro substrate adherence capacity of macrophages: endodontic implications

The disodium salt of ethylenediamine tetraacetate (EDTA) is a calcium ion chelator used in endodontics to enlarge root canals. This study investigated the effect of EDTA on substrate adherence capacity of rat inflammatory macrophages to determine if EDTA leakage to periapical tissues during root canal therapy can alter macrophage function. Inflammatory macrophages were obtained from Wistar rats and resuspended in RPMI-1640 medium. Substrate adherence capacity assays were carried out in Eppendorf tubes for 15 min of incubation at 37 degrees C in a humidified atmosphere of 5% CO2. The adherence index (AI) was calculated. Results showed that EDTA decreased substrate adherence capacity of inflammatory macrophages in a time and dose-dependent manner. The lowest EDTA concentration that caused a significant inhibition of AI was 50 mM (p < 0.05), and the EDTA concentration that caused half-maximal inhibition (IC50) was 194 +/- 20 mM (p < 0.01). Calcium chloride (10 mM) increased the adherence index of macrophages by 17.1% (p < 0.05) and decreased the EDTA inhibitory effect on AI by 49.5% (p < 0.05). We conclude that an EDTA concentration lower than that used in endodontics decreased the substrate adherence capacity of macrophages significantly. Adhesion is the first step in the phagocytic process and in antigen presentation, but leakage of EDTA to periapical tissues during root canals preparation may inhibit macrophage function and reduce periapical inflammatory reactions.

Histologic assessment of mineral trioxide aggregate as a root-end filling in monkeys

Mineral Trioxide Aggregate (MTA) has been shown in a number of experiments to be a potential root-end filling material. The purpose of this study was to examine the periradicular tissue response of monkeys to MTA and amalgam as root-end fillings. The pulps were removed from all the maxillary incisors of three monkeys. The root canals were prepared and filled with laterally condensed guttapercha and sealer, and the access cavities were restored with amalgam. Buccal mucoperiosteal flaps were raised, and root-end resections were performed before root-end cavity preparation with burs. The root-end cavities in half of the teeth were filled with MTA, while amalgam was placed in the other cavities. After 5 months the periradicular tissue response was evaluated histologically. The results showed no periradicular inflammation adjacent to five of six root ends filled with MTA; also five of six root ends filled with MTA had a complete layer of cementum over the filling. In contrast, all root ends filled with amalgam showed periradicular inflammation, and cementum had not formed over the root-end filling material, although it was present over the cut root end. Based on these results and previous investigations, MTA is recommended as a root-end filling material in man.