Dog Teeth Research Articles

A Radio Frequency Identification Implanted in a Tooth can Communicate With the Outside World

A radio frequency identification (RFID) transponder covering the 13.56 MHz band was adapted to minimize its volume so that it could be placed in the pulp chamber of an endodontically treated human tooth. The minimized transponder had a maximum communication distance of 30 mm. In an animal experiment, the transponder was fixed in the cavity of a mandibular canine of a dog. An RFID reader positioned close to the dog's face could communicate with the transponder in the dog's tooth. In certain cases, the system is applicable for the personal identification procedures for hospitalized patients instead of an identification wristband.

The effect of intracanal anti‐inflammatory medicaments on external root resorption of replanted dog teeth after extended extra‐oral dry time

The prognosis of replanted teeth depends on several factors, the most important being the length of extra-oral dry time. Studies show that after 60 min dry time, root resorption is predicted. Immediate intracanal placement of Ledermix, a paste containing triamcinolone (corticosteroid) and demeclocycline (tetracycline) has been shown to inhibit root resorption after extended dry time. However, discoloration is possible from the tetracycline in Ledermix. To evaluate the individual influence of corticosteroid and tetracycline on external root resorption after extended extra-oral dry time. Sixty-nine premolar roots of four beagle dogs were extracted and instrumented with NiTi files. Group 1 (negative control) was immediately replanted after root filling with GP and sealer; Group 2 (positive control) was root filled with GP and sealer and replanted after 60 min dry time; In groups 3-5, the canals were filled with Ledermix, Triamcinolone, and Demeclocycline, respectively, and replanted after 60 min dry time. After 4 months, the dogs were sacrificed and the roots were examined histologically for type of healing (favorable or unfavorable) and remaining root diameter. The groups treated with Ledermix, Triamcinolone and Demeclocycline had statistically significantly more favorable healing (75.8%; 69.8%; 52.4%) and more remaining root structure (5.59; 5.48; 5.09) than the group filled with GP and sealer (positive control) (0; 1.15). Corticosteroids were as effective as Ledermix at inhibiting external root resorption.

Microbial leakage and apical inflammatory response in dog's teeth after root canal filling with different sealers, post space preparation and exposure to the oral environment

Coronal leakage is an important factor affecting the outcome of endodontic therapy. This study evaluated the microbial leakage (ML) and the apical inflammatory response (AIR) in dog’s teeth after root canal filling with three endodontic sealers, post preparation and exposure to the oral environment, testing the hypothesis that there is a positive correlation between these two histological parameters (ML and AIR). Sixty-four root canals of 8 mongrel dogs were cleaned, shaped and randomly distributed into groups according to the sealer to be used: Sealer 26 (n=18); AH Plus (n=18); RoekoSeal (n=19); no sealer – control group (n=9). Root canals were filled by the lateral condensation technique. Post space preparation left 4 mm of filling material in the apical root third, and specimens were exposed to the oral environment for 90 days. The dogs were killed and jaw blocks were histologically processed using Brown & Brenn and HE staining techniques. ML and AIR were scored from 1 to 4. Results were analyzed statistically using ANOVA, Duncan’s post-hoc test and Spearman’s correlation. ML and AIR score means were: Sealer 26 - 2.44±0.98 and 2.50±0.70; AH Plus - 2.50±0.78 and 2.22±0.54; RoekoSeal - 1.84±0.95 and 2.63±0.83; Control - 2.56±1.23 and 3.11±0.60. Statistically significant differences in AIR scores were found between the AH Plus and control groups (p<0.05). Although RoekoSeal had the lowest ML means, and AH Plus, the lowest AIR means after 90-day exposure to the oral environment, no statistically significant differences were found between the three sealers under study, and no correlation was found between ML and AIR.

Reaction of the Lateral Periodontium of Dogs’ Teeth to Contaminated and Noncontaminated Perforations Filled with Mineral Trioxide Aggregate

It has been shown that the mineral trioxide aggregate (MTA) used to seal lateral/furcal perforations stimulates the deposition of newly formed cementum. Nevertheless, when the site of the perforation is contaminated, the healing process might occur under less favorable conditions. This study evaluated the repair healing process of noncontaminated and contaminated lateral perforations filled with MTA and the effect of previously filling the contaminated perforations with a bactericidal agent. Thirty lateral root perforations were prepared in endodontically treated dog's teeth, thus forming 3 groups with 10 specimens each. In group 1 the perforations were immediately sealed with MTA. In group 2 the perforations were left open for 7 days and thereafter sealed with MTA. In group 3 the perforations were left open for 7 days, filled temporarily with a calcium hydroxide-based paste for 14 days, and then sealed with MTA. The animals were killed after 90 days, and the pieces were prepared for histomorphologic and histomicrobiologic evaluations. The statistical analysis showed that group 1 had significantly better repair than groups 2 (P < .05) and 3 (P < .05), which validates the superior results obtained when MTA was immediately used to seal root perforations. Groups 2 and 3 had statistically similar repair to each other (P > .05). There were a larger number of cases of complete or partial biologic seal in group 1 compared with the contaminated groups. It might be concluded that the lateral root perforations sealed with MTA after contamination presented worse repair than the noncontaminated, immediately sealed perforations. The temporary filling with a bactericidal agent (calcium hydroxide-based paste) did not improve the repair of perforations exposed to contamination, and the contaminated groups presented similar results to each other.

Pulpal responses after application of current adhesive systems to deep cavities

The aim of the present study was to evaluate comparatively the pulpal tissue reactions of four adhesive systems placed in experimental cavities of healthy dog's teeth. Class V cavities with a mean value of remaining dentin thickness (RDT) ranging between 0.55 +/- 0.30-0.68 +/- 0.38 mm were prepared. The cavities were treated with the following adhesive systems: Etch and Prime 3.0 (EP), Single Bond (SB), Clearfil SE Bond (CSE), and Prompt L-Pop (PLP). The pulpal tissue responses to dentin adhesives were assessed histopathologically at postoperative periods of 7, 21, and 65 days, and the results were subjected to statistical analysis. A significantly greater adverse inflammatory response was observed with the materials EP and PLP, while a significantly lesser degree of disorganization in the odontoblastic zone was found with the materials SB and CSE, in the postoperative period of 65 days. In addition, a thicker predentin zone was observed where SB material was applied. Application of the selected adhesive systems to non-exposed cavities, with an RDT, which ranged between the above-mentioned rates, was correlated with slight to moderate inflammation and odontoblast reduction depending on the materials used as well as upon the RDT.

Histological Assessment of Pulp Condition after Apical Vital Root Transection in One Root of Multirooted Teeth in Dogs: A Preliminary Study

One of the most important aspects in surgery is the healing process after the periapical surgery. Past studies have shown occasional encounters with vital root resection and have noted varying degrees of pulpal response after root resection in periodontal disease. The purpose of this investigation was to observe the pulpal and periapical responses to intentional apical vital root transection in one root of multirooted teeth of German-Canadian dogs over a 6-month postoperative period. This is an experimental study performed on left maxillary and mandibular quadrants of four adult German-Canadian dogs after a 3- and 6-month period. Four teeth were assessed in each interval. One of the roots of multirooted teeth in the left quadrant of both maxillary and mandibular jaws was surgically transected. Tissue blocks were prepared by routine histological methods after 12 and 24 weeks after the surgery. The results showed a disruption of the normal pulpal architecture, with initial pulpal degeneration and subsequent early replacement by the periodontal ligament tissue after 24 weeks. Hypercementosis was seen around the apical portion of the root in all specimens. Pulpal regeneration was seen in the both upper and lower molars (p = 0.03). Resorption took place only in two specimens (p = 0.46). The inflammation in the 12th week was more than the 24th week. The pulp of multirooted teeth remains vital after transection of the apical part of the root in dogs. Longer follow-up periods are recommended because root canal therapy or extraction is indicated if resorption, necrosis, or ankylosis is seen.

Morphometric analysis of experimentally induced periapical lesions: radiographicvshistopathological findings

To evaluate the accuracy and reliability of conventional (Kodak Ektaspeed Plus film) and digitized radiographic images to detect the presence as well to estimate the size, as measured by an image analysis programme, of periapical radiolucencies induced in dog teeth in comparison with the histomorphometric data obtained from the same lesions by conventional and fluorescence microscopy. After the removal of pulp, the root canals of five premolars from the same animal were left exposed for 7 days after which they were sealed for 60 days. At day 53, three more premolars were opened and left exposed to the oral cavity for 7 days. Intact premolars were used as control. Conventional radiographs were taken at day 0, day 7, day 30, day 45 and day 60. Morphometry in digitized radiographic images and histological sections were compared at day 7 and day 60 after setting the experimental series. Radiographically, periapical lesions were only detected 30 days after coronal sealing. A progressively increasing radiolucent lesion area was observed at day 45 and day 60. Histopathologically, 7 days after pulp removal dense inflammatory infiltrate and root resorption in the periapical region was observed. At day 7 and day 60, the lesion sizes were similar when evaluated by both conventional and fluorescence microscopy. Lesion size was about 20% larger in digitized radiographs in comparison with histological measurements. Although image digitization could not improve the detection of the early stages of periapical lesions, it provides a valuable quantitative assessment of extensive periapical lesions. In addition, fluorescence light microscopy enhances the visualization of the apical and periapical structures and seems to be a highly useful tool for histological evaluation, valuable for both qualitative and quantitative studies of periapical disease.

Pulp Revascularization of Immature Dog Teeth With Apical Periodontitis

This study examined the ability of a collagen solution to aid revascularization of necrotic-infected root canals in immature dog teeth. Sixty immature teeth from 6 dogs were infected, disinfected, and randomized into experimental groups: 1: no further treatment; 2: blood in canal; 3: collagen solution in canal, 4: collagen solution + blood, and 5: negative controls (left for natural development). Uncorrected chi-square analysis of radiographic results showed no statistical differences (p >or= 0.05) between experimental groups regarding healing of radiolucencies but a borderline statistical difference (p = 0.058) for group 1 versus group 4 for radicular thickening. Group 2 showed significantly more apical closure than group 1 (p = 0.03) and a borderline statistical difference (p = 0.051) for group 3 versus group 1. Uncorrected chi-square analysis revealed that there were no statistical differences between experimental groups for histological results. However, some roots in each of groups 1 to 4 (previously infected) showed positive histologic outcomes (thickened walls in 43.9%, apical closure in 54.9%, and new luminal tissue in 29.3%). Revascularization of disinfected immature dog root canal systems is possible.

The effect of timing temporary cements to treat induced pulp necrosis in the teeth of dogs

During endodontic therapy (pulpectomy, root canal debridement and root canal filling) microbiological management is a major concern. Bacteria present in dentine tubules, apical foramina and apical delta are causally related to failure of the procedure. Studies have shown that during single session endodontic treatment bacteria remain within dental structures. The aim of the present study was to evaluate endodontic treatment performed as two sessions, using temporary endodontic dressing materials for different periods in four groups of experimental dogs. A total of 80 roots of second and third upper premolar teeth and second, third and fourth lower premolar teeth were divided into four groups. The pulp chamber was opened with burrs and the pulp exposed for 60 days to induce pulpal inflammation and necrosis. Groups II, III and IV were treated with calcium hydroxide plus camphorated paramono-chlorophenol (PMCC) for 7, 15 and 30 days, respectively. In all groups, the root canals were filled with zinc oxide-eugenol and gutta-percha cones. Clinical and radiographical measurements were performed every 2 weeks. After 60 days a small block section containing the teeth, surrounding periapical tissues and the periodontium was removed for histological and microbiological study. Histological analysis revealed intense inflammatory response in all groups. Microbiological analysis showed microbial reduction inversely proportional to the period of time that the intracanal temporary medicament was left in place.

Histopathological and histomicrobiological study of root canal therapy medication, comparison of calcium hydroxide versus gutta-percha with zinc oxide/eugenol in the teeth of dogs

The presence of microorganisms in dental structures with experimentally induced necrosis was evaluated. The materials were tested to evaluate their antimicrobial activity and tissue repair efficacy. Four dogs were used in this experiment, with a total of 64 roots of premolar teeth, divided into three groups. The root canals of Group I were filled with gutta-percha and zinc oxide/eugenol cement; Group II were filled with calcium hydroxide, and Group III were not filled. All animals were clinically and radiographically examined 15 days after surgery andthen again every subsequent 15 days until 120 days, when the teeth were extracted en bloc.Histopathological analysis showed inflammatory infiltration, cement and bone resorption andnecrotic tissue in the apical delta in different proportions. Histomicrobiological analysis showedthe presence of microorganisms inside the teeth structures, with different concentrationsaccording to the treatment used. There was statistical significance between the groups(p&gt;0.05). Gutta-percha with zinc oxide/eugenol demonstrated good antimicrobial activity;calcium hydroxide was not efficient. The conclusion of this study is that gutta-percha withzinc oxide/eugenol is the better protocol for filling root canals in dogs.

SEM evaluation of pulp reaction to different pulp capping materials in dog's teeth.

This investigation evaluates the effects of mineral trioxide aggregate (MTA), calcium hydroxide (CH) and calcium enriched mixture (CEM) as pulp capping materials on dental pulp tissues. The experimental procedures were performed on eighteen intact dog canine teeth. The pulps were exposed. Cavities were randomly filled with CEM, MTA, or CH followed by glass ionomer filling. After 2 months, animals were sacrificed, each tooth was sectioned into halves, and the interface between each capping material and pulp tissue was evaluated by scanning electron microscope (SEM) in profile view of the specimens. Dentinal bridge formation as the most characteristic reaction was resulted from SEM observation in all examined groups. Odontoblast-like cells were formed and create dens collagen network, which was calcified gradually by deposition of calcosphirit structures to form newly dentinal bridge. Based on the results of this in vivo study, it was concluded that these test materials are able to produce calcified tissue in underlying pulp in the case of being used as a pulp capping agent. Additionally, it appears that CEM has the potential to be used as a direct pulp capping material during vital pulp therapy.

Location of proliferating gingival cells following toothbrushing stimulation

Mechanical stimulation by toothbrushing promotes healing of gingivitis through accelerating cell proliferation. Junctional epithelium proliferates at periodontal pocket formation. A question is arisen whether toothbrushing contributes to the repair of gingival inflammation or deterioration of pocket formation. The location of proliferating cells in gingiva stimulated mechanically by toothbrushing was investigated. A total of 24 teeth of dogs underwent daily plaque removal with a curette (plaque removal) or both plaque removal and toothbrushing (toothbrushing). Proliferative activity of gingival cells in six individual zones was evaluated by assaying expression of proliferating cell nuclear antigen (PCNA). Toothbrushing increased densities of PCNA-positive basal cells in the junctional epithelium, connective tissues adjacent to the junctional epithelium, the alveolar bone of the oral epithelial side and the oral epithelium. However, the densities of PCNA-positive cells at the apical portion of the junctional epithelium, connective tissues adjacent to the cementum and the alveolar bone of the periodontal ligament side did not increase following toothbrushing. Toothbrushing promotes proliferation of gingival cells other than fibroblasts in periodontium and basal cells in the apical portion of the junctional epithelium. The repair of periodontal tissues might be promoted by toothbrushing within the limit of the direct mechanical stimulation.

In Vivo Effect of Calcium Phosphate Biomaterials on Dog Dental Pulp

ABSTRACTExogenous ideal delivery system for biologically active molecules is under intensive investigation. In the present study it was aimed to test the availability of different calcium phosphate biomaterials (CPBs), hydroxyapatite (HA), beta tricalcium phosphate (TCP), and a combination of these (TCP+HA) as dental pulp capping systems on healing of dog dental pulp. Experimentally perforated dental pulps of 16 premolar and molar teeth in a beagle dog were capped with CPBs. Calcium hydroxide (CH) was used as positive control. Thirty days after the operation, teeth were extracted and examined by routine histological techniques. While in HA and TCP group the pulp tissue displayed severe inflammatory response, prompted healing of the pulp tissue in TCP+HA group was seen. Complete bridge of reparative dentin formation was obvious in TCP+HA and CH groups.This study suggested that TCP+HA induced dentinogenic effect in the pulp cells of dog teeth. TCP+HA might serve as an ideal calcium phosphate pulp capping biomaterial to induce initial healing response and it might has a capacity for being a good carrier for biologically active dentinogenic molecules.

Effects of a new antibacterial adhesive on the repair capacity of the pulp‐dentine complex in infected teeth

To evaluate the effects of a self-etching/priming adhesive system, containing the antibacterial monomer 12-methacryloyloxy-dodecylpyridinium bromide (MDPB), on the repair capacity of the pulp-dentine complex in infected cavities in dog's teeth. Class V cavities with a residual dentine thickness ranging from 0.3-0.8 mm were prepared on the buccal surface of permanent teeth in four dogs. Pulpal exposures were performed in half of the cavities. Millipore filters that had been incubated for 3 h in a 10(5) milky suspension of a-streptococci were placed in the cavities, which were then filled temporarily. After 24 h, the filters were removed and both the exposed and non-exposed cavities were washed with sterile saline and assigned to four groups which were treated with either the experimental antibacterial adhesive system, or Clearfil SE bond, Dycal and Teflon discs. Stereotype connective tissue reactions (inflammatory cell response and/or tissue necrosis) and pulp-specific reparative tissue responses (reduction of odontoblasts and tertiary dentine formation) were assessed at post-operative periods of 4 and 8 weeks. Neither severe inflammation nor tissue necrosis was observed, either in the dentinal cavities or pulpal exposures treated with the self-etch adhesive containing MDPB. Rates of tertiary dentine formation in infected dentinal cavities treated with this system were comparable with those observed after dentine treatment with the Ca(OH)2-based material. Dentinal bridging was not seen in pulpal exposures treated with the experimental adhesive. The new antibacterial adhesive system maintained pulp vitality and primary odontoblastic function in infected nonexposed and exposed cavities but interfered with reparative dentine formation in infected pulpal exposures.

Association of calcium hydroxide and metronidazole in the treatment of dog's teeth with chronic periapical lesion

One of the primary objectives of endodontic treatment of teeth with pulp necrosis is the elimination of microorganisms from the root canal system, as effectively as possible, especially in cases with chronic periapical lesions. AIM: The purpose of this study was to analyze the response of the periapical tissue of dogs' teeth with chronic periapical lesions to endodontic treatment performed with utilization of metronidazole, calcium hydroxide, and an association of both as root canal dressings. METHODOLOGY: Forty root canals were submitted to pulpectomy and the root canals were kept exposed to the oral environment for 6 months. Then, they were submitted to biomechanical preparation and divided into 4 study groups with 10 specimens: group I – no root canal dressing; group II – calcium hydroxide; group III – metronidazole; group IV – calcium hydroxide associated to metronidazole. After 15 days, the root canals were filled with Fill Canal sealer. After 90 days, the animals were killed and the especimens processed for histological analysis. RESULTS: Calcium hydroxide dressing provided a significantly better outcome compared to other experimental groups (α = 0.01). Also, the results of the association of metronidazole and calcium hydroxide were similar to those observed for the metronidazole group. The worst results were obtained by the no root canal dressing group. CONCLUSION: The use of metronidazole alone or associated with Calcium hydroxide, did not improve periapical healing when compared to Calcium hydroxide dressing.

Biological response of pulps submitted to different capping materials

Pulp capping is a procedure that comprises adequate protection of the pulp tissue exposed to the oral environment, aiming at the preservation of its vitality and functions. This study evaluated the response of the dental pulps of dog teeth to capping with mineral trioxide aggregate (MTA) or calcium hydroxide P.A. For that purpose, 37 teeth were divided into two groups, according to the capping material employed. Two dogs were anesthetized and, after placement of a rubber dam, their pulps were exposed in a standardized manner and protected with the experimental capping materials. The cavities were then sealed with resin-modified glass ionomer cement and restored with composite resin. After sixty days, the animals were killed and the specimens were processed in order to be analyzed with optic microscopy. It was observed that MTA presented a higher success rate compared to calcium hydroxide, presenting a lower occurrence of infection and pulp necrosis.

Histologic evaluation of pulpotomy performed with ethyl-cyanoacrylate and calcium hydroxide

The aim of this study was to evaluate histological aspects of the pulp-dentin complex of dogs submitted to pulpotomy and capped with ethyl-cyanoacrylate and calcium hydroxide. Thirty dog teeth were divided into 2 groups of 15 as follows: Group 1 - ethyl-cyanoacrylate; Group 2 - calcium hydroxide. The pulpotomies were carried out following all of the treatment precautions recommended for dogs. After 30 days the specimens were submitted to histological preparation and were then blindly evaluated by a histologist. Data were analyzed statistically by the Fisher exact test, comparing the two groups. After 30 days, the presence of a hard tissue barrier was observed in 83.3% of Group 1, and in 100% of Group 2 (p = 0.478). A continuous hard tissue barrier was observed in 50% of the ethyl-cyanoacrylate group and 75% of the calcium hydroxide group (p = 0.652). It can be concluded that both materials induced hard tissue barrier formation, but Group 2 had a higher percentage than Group 1, with no significant statistical differences; the differences observed between the different barriers (continuous/non-continuous) were not significant between groups and there was no pulpal necrosis in either group.

Pulp response of anionic lyophilized collagen matrix with or without hydroxyapatite after pulpotomy in dog's teeth

The aim of the present study was to evaluate histologically the pulp response of anionic lyophilized collagen matrix with or without hydroxyapatite as a biomaterial pulp-capping agent in pulpotomy of dogs' teeth. Sixty pre-molar roots from three dogs were used. After pulpotomy, the remaining pulp tissue was capped with one of the following materials: Group I (20 roots): anionic lyophilized collagen matrix; Group II (20 roots): anionic lyophilized collagen matrix associated with hydroxyapatite; Group III (10 roots): calcium hydroxide (p.a.) paste in saline; Group IV (10 roots): zinc oxide eugenol cement. After 90 days the animals were killed by anesthetic overdose and the teeth were removed and submitted to histological processing. According to the histopathological results, we concluded that the zinc oxide eugenol cement and anionic lyophilized collagen matrix with or without hydroxyapatite did not present satisfactory pulp response and that calcium hydroxide is the suitable material for pulpotomy.

Evaluation of periapical repair following retrograde filling with different root-end filling materials in dog teeth with periapical lesions

The objective of this study was to evaluate periapical repair following retrograde filling using different root-end filling materials. After induction of periapical lesions, 48 root canals from dog teeth were partially filled. Endodontic surgery was performed and 3 different materials were used for root-end filling: Sealer 26, Sealapex plus zinc oxide, or mineral trioxide aggregate (MTA). No additional procedures were performed in the control group after partial filling of the root canal. After 180 days, the animals were killed, the maxillas and mandibles were removed, and specimens were submitted for histologic processing. Histopathologic analysis revealed similar periapical repair for the groups in which Sealer 26, Sealapex plus zinc oxide, and MTA were used (P > .05). The control group showed unsatisfactory periapical repair (P < .05). There was no difference in periapical tissue healing after retrograde filling with the tested materials, which indicates that these 3 root-end filling materials are equally useful.

Effect of proliferating tissue on transplanted teeth in dogs

The objective of this study was to investigate the effect of transplanted proliferating tissue on the regeneration of periodontal ligaments (PDL) in tooth transplantation. Two weeks after removing the alveolar bone, proliferating tissues were excised and examined for expression of basic fibroblast growth factor (bFGF) and alkaline phosphatase (ALP) using a LightCycler. Next, the teeth to be transplanted (first premolars) were extracted and PDLs were removed by scaling. After that, the first premolar teeth and proliferating tissues for the experimental group were transplanted into bone cavities created at the sites of the third and fourth premolars, while the control sites received teeth only. Finally, 1, 2, and 4 weeks later, the animals were sacrificed and specimens were collected and processed for histopathologic examination. bFGF and ALPmRNA showed a significant increase in the transplanted proliferating tissue. Transplantation of the proliferating tissues positively affected the formation of new cementum and PDL. Moreover, application of the transplanted proliferating tissues decreased the occurrence and extent of ankylosis and root resorption at the root surface. These results indicate that transplanted proliferating tissue may promote the regeneration of periodontal tissue and prevent ankylosis and root resorption following the transplantation of teeth.