The effect of the filling material in the tissue reactions following apical plugging of the root canal with dentin chips. A histologic study in monkeys' teeth

Apexification of an Endodontically Failed Permanent Tooth with an Open Apex: A Case Report with Histologic Findings

The management of an endodontic failure in a traumatized tooth with an open apex presents a major dilemma. The arrest of root growth after traumatic injury is a substantial consequence of pulpal necrosis. Conventional endodontic treatment procedures will be challenging by the resulting thin, fragile dentinal walls, which will impede the appropriate debridement and optimal apical sealing. Apexification is a well-established procedure that is designed to treat or preserve a tooth with an incomplete root apex and necrotic pulpal tissue by promoting the formation of a calcified apical barrier through the application of a bioactive substance at the root apex. The present case report demonstrates a successful apexification procedure for an endodontically failed permanent central incisor with an open apex with a two-year follow-up time. The clinical and radiographical results revealed the absence of signs and symptoms and the formation of hard tissue at the root apex. The tooth was extracted for prosthodontic reasons and processed for histologic examination. The histologic evaluation revealed dentin-like and cementum-like tissues formed at the apical barrier.

Apical Closure in Apexification: A Review and Case Report of Apexification Treatment of an Immature Permanent Tooth with Biodentine

Materials such as calcium hydroxide paste and mineral trioxide aggregate are used in apexification treatment of immature permanent teeth, but the search for improved materials with higher characteristics of biocompatibility results in different materials. Biodentine is a tricalcium silicate cement that possesses adequate handling characteristics and acceptable mechanical and bioactivity properties. This report describes the case of a 9-year-old boy who was referred to the Department of Dental Clinic of Querétaro Autonomous University of Mexico. One month prior the patient had suffered a dental trauma of his upper left central incisor and had been treated by another dentist. The clinical diagnosis was previously initiated therapy and symptomatic apical periodontitis. The treatment was apexification with Biodentine. At follow-ups performed at 3, 6, and 18 months after treatment the tooth was asymptomatic. The cone-beam computed tomography scan at 18-month postoperative follow-up revealed continuity of periodontal ligament space, absence of periapical rarefactions, and a thin layer of calcified tissue formed apical to the Biodentine barrier. On the basis of sealing ability and biocompatibility, apexification treatment with Biodentine was applied in the present case report. The favorable clinical and radiographic outcome in this case demonstrated that Biodentine may be an efficient alternative to the conventional apexification materials.

Dental Stem Cell Migration on Pulp Ceiling Cavities Filled with MTA, Dentin Chips, or Bio-Oss

MTA, Bio-Oss, and dentin chips have been successfully used in endodontics. The aim of this study was to assess the adhesion and migration of dental stem cells on human pulp ceiling cavities filled with these endodontic materials in an experimental model, which mimics the clinical conditions of regenerative endodontics. Cavities were formed, by a homemade mold, on untouched third molars, filled with endodontic materials, and observed with electron microscopy. Cells were seeded on cavities' surface and their morphology and number were analysed. The phenomenon of tropism was assessed in a migration assay. All three materials demonstrated appropriate microstructures for cell attachment. Cells grew on all reagents, but they showed a differential morphology. Moreover, variations were observed when comparing cells numbers on cavity's filling versus the surrounding dentine disc. The highest number of cells was recorded on dentin chips whereas the opposite was true for Bio-Oss. This was confirmed in the migration assay where a statistically significant lower number of cells migrated towards Bio-Oss as compared to MTA and dentin chips. This study highlights that MTA and dentin chips have a greater potential compared to Bio-Oss regarding the attraction of dental stem cells and are good candidates for bioengineered pulp regeneration.

Treatment options: apexogenesis and apexification

This article will describe requirements for case selection and review the procedures for apexogenesis and apexification in immature permanent teeth. Nonclinical and clinical data will be presented to support the recommendations, and outcomes will be presented from clinical studies. The dental pulp is an ectomesenchymally derived connective tissue with certain unique properties such as being encased in hard tissues, which limits its collateral circulation. The pulp provides a matrix for binding of its cells and provides support allowing communication between the cells. In addition to immune cells, the dental pulp contains odontoblasts, which are specialized cells capable of producing dentin. In the absence of a vital pulp, dentin deposition is arrested. When an immature tooth is affected by caries or trauma, the pulp requires proper management according to the degree of inflammation and its vitality. Maintenance of pulp vitality will allow continued root development along the entire root length. If the pulp is irreversibly inflamed or necrotic, root-end closure procedures are required when the apex has not fully formed.

Calcium hydroxide: study based on scientific evidences

The characteristics of calcium hydroxide come from its dissociation into calcium and hydroxyl ions. The action of these ions on tissues and bacteria explains the biological and antimicrobial properties of this substance. Under the conditions of this retrospective of literature, based on scientific evidences, it is possible to state that: 1. Dentin is considered the best pulpal protective, and calcium hydroxide has proved, through numerous studies, its capability of inducing the formation of a mineralized bridge over pulpal tissue. 2. It is necessary, whenever possible, to provide time for calcium hydroxide paste to manifest its potential of action on the microorganisms present in endodontic infections. The maintenance of a high concentration of hydroxyl ions can change bacteria enzymatic activity and promote its inactivation. 3. The site of action of hydroxyl ions of calcium hydroxide includes the enzymes in the cytoplasmic membrane. This medication has a large scope of action, and therefore is effective on a wide range of microorganisms, regardless their metabolic capability. In microbial world, cytoplasmic membranes are similar, irrespective from microorganisms morphological, tinctorial and respiratory characteristics, which means that this medication has a similar effect on aerobic, anaerobic, Gram-positive and Gram-negative bacteria. 4. Calcium hydroxide as temporary dressing used between appointments promotes better results on the periapical healing process than the treatment in one appointment.

In vitro study of the effects of Nd:YAG laser irradiation on the apical sealing of endodontic fillings performed with and without dentin plugs

OBJECTIVE

The aim of this study was to evaluate the effects of Nd:YAG laser irradiation on the apical sealing of root canal fillings with or without a dentin plug.

BACKGROUND DATA

Previous studies have shown that Nd:YAG laser irradiation of root canal wall dentin promotes its melting, recrystallization, and therefore a less permeable surface.

MATERIALS AND METHODS

Thirty extracted and endodontically treated teeth were divided into three groups. Eight specimens of each group were evaluated by means of quantitative analysis, measuring the marginal apical dye leakage. The remaining two specimens were evaluated by means of qualitative analysis, using the scanning electron microscopy (SEM). For the quantitative analysis, the samples of group I were obturated. In group II, the apical third of the samples were irradiated by the Nd:YAG laser at four exposures of 100 mJ/pulse, 1 W, 10 Hz, 3 sec, and obturated. In group III, an apical dentin plug was condensed and lased using the same parameters of group II, and the root canals were obturated. The samples evaluated by SEM were prepared as those analyzed quantitatively; however, their root canals were not filled.

RESULTS

There were statistically significant differences among the groups regarding dye leakage. Group II showed the minor leakage average, followed, in order, by groups I and III. SEM analysis revealed open dentinal tubules in group I; melting and recrystallizing of the apical root dentin in group II; and melting and recrystallizing of a portion of the dentin plug in group III.

CONCLUSION

The Nd:YAG laser irradiation of the root canal apical third without the presence of dentin plug significantly improved the quality of the apical sealing under the experimental conditions tested.

Long-term radiographic and histological observations of endodontically treated teeth

Endodontic therapy was performed on 14 teeth in juveniles with inflamed or necrotic pulps. The patients were recalled at 6-month intervals for radiological and clinical examinations. After 1 yr, periapical surgery was performed on six teeth. After 18 months, 5 more patients were subjected to periapical surgery and, after 2 1/2 years, 3 more patients had periapical surgery. A small block section containing the root tip and surrounding tissues was removed from all of the patients. Radiographs showed reductions in size, but not elimination, of periapical lesions. Histological examinations revealed that most root canals were overfilled. Inflammation persisted around zinc oxide-eugenol particles beyond the tooth apexes. In addition, gutta-percha overfilling enhanced the proliferation of cell rests of Malassez. In some cases, dentin filings were found at and beyond the tooth apexes. The formation of new hard tissue was stimulated by the presence of dentin chips.

An experimental study of the sealing ability of a dentinal apical plug treated with bonding agent

The purpose of this study was to evaluate the sealing ability of a dentinal apical plug treated with a bonding agent. Ninety human lower premolars were used. The teeth were divided into three groups. in groups 1 and 2, to prepare an apical isthmus of 1 mm in length, the first apical seat was prepared with a #45 K file 1 mm short of the anatomical apex and with a #60 K file 2 mm short for the second apical seat. Dry dentin fillings were packed in the apical isthmus with a #60 K file. In group 1, the root canal was obturated with gutta-percha and Canals root canal sealer by the lateral condensation method. In group 2, following an application of the bonding agent to the plug, the root canal was obturated in the same way. In group 3 (control), a single apical seat was prepared with a #60 K file 1 mm short of the apex and the root canal was obturated similarly. The teeth of three groups were immersed in a 1% methylene blue solution for 1, 2, and 4 wk. Dye penetration depth from the apical foramen was determined. Group 2 showed no leakage after 4 wk. Groups 1 and 3 showed dye penetration into the root canal, and in these two groups dye penetration increased with time.

Biological evaluation of collagen gels containing calcium hydroxide and hydroxyapatite

Dentinal chips and different biocompatible materials have been used in the past as apical plugs to enhance healing and simplify obturation. The purpose of this study was to evaluate bone reactions to implants of hydroxyapatite, collagen, and calcium hydroxide, alone or in different combinations. The materials were implanted bilaterally in the mandibles of 36 guinea pigs and the reactions were compared histologically over a period of 16 wk. No major inflammatory reactions were observed in any of the implant combinations. Hydroxyapatite was not resorbed over the examination periods, but calcium hydroxide and collagen implants were partially or totally resorbed and replaced by bony tissue. The results indicate that cylinders which may be useful as apical plugs can be performed and will heal with minimal biological reactions.

An evaluation of the biocompatibility of a glass ionomer-silver cement in rat connective tissue

Pellets of a glass ionomer-silver cement and a zinc oxide-eugenol cement were implanted into the soft tissues and bones of 30 rats. Following experimental periods of 14, 30, and 80 days, the animals were killed and tissue sections were prepared. The responses to each of the materials initially and at 30 days consisted of mild inflammation. No severe inflammatory responses were noted in any of the groups. By 80 days, although mild inflammation persisted, the materials appeared to be well tolerated. Bone apposition occurred in the glass ionomer-silver cement group; the zinc oxide-eugenol group produced fibrosis.