Endodontic treatment of experimental root perforations in dog teeth

Root perforations: aetiology, management strategies and outcomes. The hole truth

The purpose of this clinical article is to emphasise that root perforations can occur both during and after endodontic treatment. These reduce the chance of a successful treatment outcome and can jeopardise the survival of the tooth. The aetiology and diagnosis of root perforations are described. The article also focusses on the non-surgical and surgical management of root perforations and describes how selection of the appropriate treatment depends on an accurate diagnosis.

A Review on Perforation Repair Materials

Perforation is an artificial communication between the root canal system and supporting tissues of the teeth. Root perforation complicates the treatment and deprives the prognosis if not properly managed. A wide variety of materials to seal the perforations have been suggested in literature. There are many comparative studies showing the efficacy of one material over the other. Literature shows many reviews on diagnosis, treatment plan and factors affecting prognosis of perforation repair; but none of these articles elaborated upon various materials available to seal the perforation. The present article aims at describing all the materials used for perforation repair from the past till date; it also offers a literature review of all the articles published over last four decades referred to the treatment of perforation with various root repair materials.

Properties and applications of calcium hydroxide in endodontics and dental traumatology

Calcium hydroxide has been included within several materials and antimicrobial formulations that are used in a number of treatment modalities in endodontics. These include, inter-appointment intracanal medicaments, pulp-capping agents and root canal sealers. Calcium hydroxide formulations are also used during treatment of root perforations, root fractures and root resorption and have a role in dental traumatology, for example, following tooth avulsion and luxation injuries. The purpose of this paper is to review the properties and clinical applications of calcium hydroxide in endodontics and dental traumatology including its antibacterial activity, antifungal activity, effect on bacterial biofilms, the synergism between calcium hydroxide and other agents, its effects on the properties of dentine, the diffusion of hydroxyl ions through dentine and its toxicity. Pure calcium hydroxide paste has a high pH (approximately 12.5-12.8) and is classified chemically as a strong base. Its main actions are achieved through the ionic dissociation of Ca(2+) and OH(-) ions and their effect on vital tissues, the induction of hard-tissue deposition and the antibacterial properties. The lethal effects of calcium hydroxide on bacterial cells are probably due to protein denaturation and damage to DNA and cytoplasmic membranes. It has a wide range of antimicrobial activity against common endodontic pathogens but is less effective against Enterococcus faecalis and Candida albicans. Calcium hydroxide is also an effective anti-endotoxin agent. However, its effect on microbial biofilms is controversial.

In vitro evaluation of the sealing ability of MTA used for the repair of furcation perforations with and without the use of an internal matrix

OBJECTIVE

To evaluate the effect of matrix on mineral trioxide aggregate (MTA) when used to repair furcal perforations.

STUDY DESIGN

Forty-five human molars with furcal perforations were randomly divided into 3 groups and repaired with MTA either alone or over a barrier (calcium sulfate or Collaplug). Eight teeth without perforations provided negative control samples. After assessing repair quality, 1 mol/L glucose solution was used as the tracer to detect the leakage. The concentration of leaked glucose was measured after 1, 2, 4, 7, 15, and 20 days using a glucose oxidase method.

RESULTS

No significant difference in either leakage or overfilling was found between the groups with Collaplug and MTA alone (P > .05). Although no overfilling was detected in the group with calcium sulfate, that group had the most leakage (P < .05).

CONCLUSIONS

Neither of the 2 internal matrices improved the sealing ability and reduced the incidence of overfilling simultaneously.

The use of white Portland cement as an apical plug in a tooth with a necrotic pulp and wide-open apex: a case report

AIM

To present a case in which substantial periapical healing occurred with the use of white Portland cement (WPC) to create an apical plug in the root of an immature tooth.

SUMMARY

Radiographic examination indicated an immature tooth (35) with a wide-open apex and a periapical radiolucency. The canal was mechanically cleaned using intracanal instruments and 5% NaOCl irrigation. Small pieces of resorbable collagen sponge were packed beyond the root apex with the aim of creating a periapical barrier for the compaction of filling material. WPC powder was then mixed with sterile water and delivered to the apical portion of the canal (approximately 3 mm). The patient was asked to return 1 week later for the continuation of treatment but he did return as planned. Seven months after the intervention the patient returned and another radiograph was exposed to reveal complete radiographic healing of the periapical region. The remainder of the canal was filled with thermoplastic gutta-percha. Clinical follow-up 1 year later revealed adequate clinical function, absence of clinical symptoms and no signs of periapical rarefaction.

KEY LEARNING POINT

The positive clinical resolution of this case is encouraging for the use of WPC as an apical plug in immature teeth with necrotic pulps and wide-open apices.

Connective Tissue Grafting on Resin Ionomer in Localized Gingival Recession

BACKGROUND

One of the main objectives of periodontal reconstructive surgery is the coverage of exposed roots that occur due to gingival recession. On some occasions, where a caries, root resorption, or amalgam restoration exists on the exposed root surface, the treatment planning becomes more complex. This case report describes the use of a subepithelial connective tissue graft (SCTG) on a resin ionomer-restored root surface to treat gingival recession that is complicated with the above-mentioned handicaps.

METHODS

An amalgam restoration and carious lesion were removed following full-thickness flap reflection, and the cavity was restored with glass ionomer cement. An SCTG was placed onto the restoration, and the flap was coronally positioned. A porcelain crown restoration was performed 9 months after surgery.

RESULTS

At 3-, 6-, and 9-month follow-ups, probing depths were reduced and gain in attachment level was obtained with no clinical signs of inflammation in gingiva. Monthly periodontal controls revealed that creeping attachment had occurred on the restoration during the follow-up periods.

CONCLUSION

This single case report serves as a good example to show that SCTG can be successfully performed to treat gingival recession associated with a glass ionomer-restored root surface.

Restoration of the root-filled tooth: pre-operative assessment

This is the first in a series of four papers related to the management of root canal treated teeth. When teeth compromised by extensive restorations become non-vital, suggestions have been given as to how root canal treatment can be carried out with the greatest chance of success. Once root canal treated, either by a previous dentist or by the current dentist, a review of the assessment process that should be carried out prior to placing costly indirect definitive restorations is given. It will be clear that post-retained restorations are mainly reserved for anterior or single-rooted teeth, posterior teeth rarely requiring a post for core retention. The second paper in this series describes the basic tooth preparation that should be carried out prior to placing a post. Depending on the type of post system used, further modifications to tooth preparation may be required and the cementation techniques may also have to be modified. The third paper therefore discusses the various post types, when and how they should be used for optimum results. The final paper addresses reinforcement and restoration of compromised root canals, such as those with immature, open apices, or those that have been over-prepared for previous post-retained restorations.

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.

Sealing effectiveness of materials used in furcation perforation in vitro

OBJECTIVES

In this study the sealing ability of various materials used to repair furcation perforations was evaluated.

DESIGN

Ninety human molars were endodontically treated and a perforation was made in the pulp chamber floor using a round bur. The teeth were inserted into a moistened flower sponge and perforation sites were sealed with one of the following materials: Mineral Trioxide Aggregate (ProRootM), Super-EBA, Vitremer, Hemarcol together with Super-EBA, Hemarcol together with Vitremer, Tricalcium phosphate together with AH26, Cavit W and amalgam. After eight months, the sealing effectiveness of the materials was evaluated in a double-blinded trial under a video-microscope by detecting the penetration of silver nitrate solution (50%w/w) in longitudinal tooth sections.

RESULTS

Perforation sites filled with Hemarcol together with Vitremer or with MTA exhibited statistically less silver stain penetration while Cavit W or Tricalcium phosphate together with AH26 sealer failed to effectively seal the perforation sites.

CONCLUSIONS

MTA alone or Vitremer in combination with a collagen sponge can be used effectively in the treatment of perforations in a furcation area.

Pathologic interactions in pulpal and periodontal tissues

Both endodontic and periodontal disease are caused by a mixed anaerobic infection. The pathways for the spread of bacteria between pulpal and periodontal tissues have been discussed with controversy. This article is an attempt to provide a rational approach to the perio-endo/endo-perio question based on a review of the relevant literature. In the light of evidence, clinical concepts for the diagnosis and treatment of lesions involving both periodontal and pulpal tissues are discussed.

Effect of sodium hypochlorite and EDTA on mercury released from amalgam

OBJECTIVES

The effect of sodium hypochlorite (NaOCl) and EDTA on mercury released from dental amalgam was assessed in vitro.

STUDY DESIGN

Fifty-six samples of dental amalgam of similar size were prepared and exposed to a 10-mL solution of either 1% NaOCl, 3% NaOCl, 10% EDTA in 1% NaOCl, or 10% EDTA in 3% NaOCl for periods of 20, 40, and 60 minutes. Mercury concentrations in the solutions were measured by using a cold-vapor atomic absorption Mercury Analyzer System, and the differences between the groups were statistically analyzed.

RESULTS

All amalgam samples exposed to 1% NaOCl and 3% NaOCl-either alone or in combination with EDTA-released mercury into the solutions. Mercury release was significantly higher in the test groups than in the EDTA, distilled water, or phosphate buffer controls (P <.001). Increase in the mean concentration levels of mercury in solution was time-dependent and directly related to NaOCl concentration. The addition of EDTA caused a reduction in mercury levels detected in solution, which was more significant in amalgam samples exposed to 1% NaOCl combined with EDTA (P <.001).

CONCLUSIONS

NaOCl solutions commonly used for root canal cleaning and shaping cause mercury release from dental amalgam and may alter its chemo-physical properties as a sealant for root perforations.

Sealing furcation perforations with silver glass ionomer cement: an in vitro evaluation

Furcation perforations sealed with silver glass ionomer cement (Chelon Silver) were evaluated in vitro compared with amalgam. Access cavities were prepared in 25 extracted human molar teeth. The coronal orifices of the root canals were sealed with amalgam and varnish. Naturally occurring coronal leakage through the intact pulp chamber floor was determined quantitatively for each tooth, using a modified fluid transport model, under pressure of 1.2 Atm. Each tooth was then disconnected from the system, perforated at the furcation, and the perforation sealed with either Chelon Silver (10 teeth) or amalgam (10 teeth); five remaining teeth served as a negative control. After incubation for 24 h at 37 degrees C in 100% humidity, teeth were reconnected to the modified fluid transport system, and coronal leakage under pressure was evaluated at 1, 2, 6, 15, and 24 h. Leakage through each tooth was compared with that of its own intact pulp chamber floor before perforation and the groups compared with each other. No significant difference was found between the mean leakage of the intact pulp chamber floors of the two groups. Chelon Silver had a significantly better sealing ability than amalgam (p < 0.01): leakage rate of 0.007 and 0.017 microliter/min, respectively. It is concluded that Chelon Silver could be an adequate sealer for furcation perforations.

Histological evaluation of repair using a bioresorbable membrane beneath a resin-modified glass ionomer after mechanical furcation perforation in dogs' teeth

Resorbable barriers have been shown both clinically and histologically to produce favorable periodontal regenerative outcomes. The purpose of the present study was to evaluate the histological response to one such resorbable barrier (Atrisorb) when used as a matrix under a resin-modified glass ionomer (RMGI) sealant in the repair of furcation perforations in experimental animals. After anesthesia, pulp extirpation and filling of radicular canals with zinc oxide-eugenol cement, furcal perforations were made in 30 lower premolar (P2, P3, and P4) teeth of labrador dogs with a 1 mm diameter round bur in a conventional handpiece. The perforated teeth were randomly divided into two groups of 15 teeth. Group 1 teeth were treated with RMGI alone and group 2 with the resorbable barrier under RMGI. Six teeth without perforations served as negative controls. Pulp chambers of all teeth were filled with RMGI cement. Animals were sacrificed after 3 months. The teeth and the surrounding structures were processed for light microscopy. There were no differences found between results for glass ionomer alone and barrier with glass ionomer. The conclusion of this study is that placement of a resorbable barrier at the pulp chamber aspect of a furcation perforation did not result in superior healing, compared with the use of resin-modified glass ionomer alone.

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.

An in vitro study of furcation perforation repair using calcium phosphate cement

Furcation perforations created in the pulpal floors of 30 extracted human molars were repaired with either light-cured glass ionomer cement (GI), calcium phosphate cement (CPC), or light-cured glass ionomer cement placed over a CPC matrix (M). After the cement was set, the teeth were immersed in India Ink for 48 h, dried, and sectioned longitudinally. Dye penetration into the furcation repair was independently evaluated by three board-certified endodontists. There was no significant difference in the mean extent of dye leakage among the three experimental groups. The use of CPC, with its enhanced biocompatibility, potential for osteoconduction, and sealing ability, may improve the prognosis of teeth with furcation perforations.

Treatment of root perforations with calcium hydroxide and SuperEBA cement: a clinical report

Iatrogenic root perforations sometimes occur during root canal treatment or when preparing the root canal for a post. The inflammation in the periradicular tissues caused by root perforation reduces the prognosis of the involved tooth. The situation may be further complicated if by coronal leakage, microorganisms are allowed to infect the canal and the periradicular region. This clinical report presents a nonsurgical technique, based on the internal matrix concept, using both calcium hydroxide and SuperEBA together to repair root perforations. The author has experienced good clinical results with this perforation repair technique.

Root perforations: classification and treatment choices based on prognostic factors

Root perforations are common complications of endodontic treatment or post preparation and often lead to tooth extraction. Successful treatment depends mainly on immediate sealing of the perforation and prevention of infection. Several factors affect the achievement of these goals, most important of which are: time of occurrence, size, and location of the perforation. A classification of root perforations, based on the above factors, is presented to assist the clinician in the choice of the treatment protocol which will give the best possible results when a perforation is diagnosed.

Repair of furcal perforations with mineral trioxide aggregate: two case reports

Furcal perforation is an unfortunate incident that can occur during root canal therapy or post preparation of multirooted teeth. Studies have shown that the materials currently used to repair these iatrogenic accidents are inadequate. The poor prognosis of furcation perforations is probably due to bacterial leakage or lack of biocompatibility of repair materials. On the basis of the recent physical and biologic property studies of the newly introduced mineral trioxide aggregate, this material may be suitable for closing the communication between the pulp chamber and the underlying periodontal tissues. These case reports support this hypothesis.

Use of mineral trioxide aggregate for repair of furcal perforations

The histologic response to intentional perforation in the furcations of 28 mandibular premolars in seven dogs was investigated. In half the teeth, the perforations were repaired immediately with either amalgam or mineral trioxide aggregate; in the rest the perforations were left open to salivary contamination before repair. All repaired perforations were left for 4 months before histologic examination of vertical sections through the site. In the immediately repaired group, all the amalgam specimens were associated with inflammation, whereas only one of six with mineral trioxide aggregate was; further, the five noninflamed mineral trioxide aggregate specimens had some cementum over the repair material. In the delayed group, all the amalgam specimens were associated with inflammation; in contrast only four of seven filled with the aggregate were inflamed. On the basis of these results, it appears that mineral trioxide aggregate is a far more suitable material than amalgam for perforation repair, particularly when used immediately after perforation.

Effect of dentin preparation and acid etching on the sealing ability of glass ionomer and composite resin when used to repair furcation perforations over plaster of Paris barriers

Access openings and furcation perforations were prepared in 60 human extracted teeth and randomly divided into four equal groups. Plaster of Paris barriers were created in all perforations. The defects were obturated using either glass ionomer or composite resin with or without acid etching of the dentin. The pulp chambers and access openings were filled with composite resin. After immersion in 2% methylene blue solution for 2 weeks, the teeth were sectioned longitudinally and dye penetration was measured under a stereomicroscope using the NIH Image 1.47 Macintosh program. The results indicated that light-cured glass ionomer provided a significantly better seal than did the light-cured composite resin with or without dentin preparation and acid etching. The glass ionomer allowed significantly less dye penetration when used on etched dentin than it did on nonetched dentin.

An in vitro evaluation of plaster of Paris barriers used under amalgam and glass ionomer to repair furcation perforations

Furcation perforations were created in the pulpal floor of 60 teeth and were repaired with amalgam alone, plaster of Paris under amalgam, light-cured glass ionomer alone, and plaster of Paris under light-cured glass ionomer. After the access openings were filled with composite resin, the teeth were immersed in 2% erythrocin B dye solution for 2 wk, sectioned longitudinally, and dye penetration was measured. The light-cured glass ionomer group provided the least amount of leakage, followed by the group of plaster of Paris under glass ionomer. The groups using amalgam alone and plaster of Paris under amalgam showed the most leakage. The plaster of Paris barrier prevented the overextension of the repair materials when used under amalgam and glass ionomer.

Root perforations. A review of literature

Root perforations that result in a communication of the root space with the periodontal tissues occasionally occur during endodontic procedures. They may be induced iatrogenically, by resorptive process, or by caries. Identification of root perforations is possible by direct observation of bleeding, indirect bleeding assessment using a paper point, radiography, and an apex locator. Prognosis of a tooth with root perforation depends on the time lapsed before obturation of the perforation, location and size of the lesion, and the sealability of the repair material. Perforation defects may be repaired by nonsurgical or surgical techniques. A review of causes, diagnosis, prognosis, and management of root perforations provides information for avoiding, detecting, and treating of such defects.

Comparative study of the sealing ability of light-cured versus chemically cured materials placed into furcation perforations

Two light-cured materials, Vitrebond and Prisma VLC Dycal, were compared with two chemically cured materials, Ketac Fil and Dycal, for ability to seal furcation perforations. Access openings and furcation perforations were prepared in 60 teeth and randomly divided into four equal groups. Furcation perforations were repaired with each of the tested materials, and the access openings were filled with composite resin. After teeth were immersed in 2% erythrocin B dye solution for 10 days, they were sectioned longitudinally and dye penetration was measured. The light-cured materials allowed statistically significant less dye leakage than did the chemically cured materials.

Treatment of root-fractured maxillary incisor with Thermafil obturator

This case report describes the treatment of a maxillary left central incisor with intra-alveolar horizontal root fracture in the middle of the root. The pulp of the coronal segment was necrotic and endodontic treatment was performed. Instrumentation of the root canal through the fracture line was carried out and the tooth was obturated with Thermafil in order to bring about a union of the fragments. At the 24-month follow up examination the tooth was functionally and esthetically normal. Radiographically no pathosis was evident in the periapical or fracture areas.

Healing of furcation perforations in primate teeth after repair with decalcified freeze-dried bone: a longitudinal study

Furcation perforations were created in 18 maxillary and mandibular molars in three adult rhesus monkeys. The perforations were located in the center of the pulp chamber floor and were 1 mm in diameter and 3 mm in depth. Teflon was used as a negative control to cover the perforation site in three teeth and the bony defects in the other 15 teeth were filled with decalcified freeze-dried bone. At the end of the 6-month experimental period the gingival tissues were clinically healthy, there was normal sulcular probing depths around all teeth, and only one tooth demonstrated furcal bone loss, radiographically. The histological picture for the Teflon and decalcified freeze-dried bone groups was very similar. There was a layer of epithelium immediately beneath the perforation site and deep to this was fibrous connective tissue and bone. Chronic inflammation was present in the connective tissue of all 3 Teflon samples but in only 2 of the 15 decalcified freeze-dried bone samples. New bone formation was not observed in any of the samples.

Evaluation of the sealing ability of amalgam, Cavit, and glass ionomer cement in the repair of furcation perforations

Perforations created in the pulpal floors of 30 extracted molars were repaired with amalgam, Cavit, and light cured glass ionomer cement. After the pulp chambers and access openings were filled with composite resin, the teeth were then immersed in 2% Erythrocin B solution for 1 week. After longitudinal sectioning of the teeth, dye penetration was measured. The results indicated significant differences between the three materials. Light cured glass ionomer exhibited the least dye penetration followed by Cavit and amalgam.

Histological study of furcation perforations treated with tricalcium phosphate, hydroxylapatite, amalgam, and Life

One-hundred twenty experimental furcation perforations were created in the mandibular and maxillary premolars and molars of six rhesus monkeys. Tricalcium phosphate, hydroxylapatite, amalgam, and Life were used to repair the furcation perforations. The animals were sacrificed at the intervals of 2, 4, and 6 months after the experiment. Histological evaluation revealed lack of complete healing of furcation perforations repaired with any materials. Epithelium was present in the furcation perforations in both experimental and positive control groups. No hard tissue formation was observed in this study. Inflammation in the furcation area may be due to inadequate sealing ability of the repair materials.

A clinical and roentgenological study of 55 cases of root perforation

The treatment outcome of 55 root perforations in man were related to pretreatment conditions and various treatment procedures used, with a mean recall period of 3 years 5 months. In this study maxillary teeth were perforated three times more often (74.5 per cent) than mandibular teeth (25.5 per cent); 47 per cent of the perforations were due to endodontic and 53 per cent due to prosthodontic treatment. The buccal and mesial root surfaces as well as the midroot areas were most often perforated. In 25 per cent, radiographic changes were directly related to the perforated areas. Twenty-eight perforations were repaired by orthograde fillings with gutta-percha and Kloro-percha N-phi; eight received a combined orthograde and surgical repair, and in only three cases a surgical approach was used. Four cases received no treatment but were recalled, and twelve perforations showed a size and location hopeless for repair; the teeth were therefore extracted. Five failures of the primary orthograde treatment group later underwent surgical treatment and were followed up for 3 years 3 months. The overall success rate in the primary treatment group of teeth was 56 per cent while 36 per cent became failures. Five failures were retreated, and four of these became successful. A combined orthograde and surgical repair of the perforations provided the most favourable outcome with 92 per cent successful. The study stresses the importance of preventing this type of treatment complication.