Resorption Cavities Research Articles

Irrigant flow characteristics in the root canal with internal root resorption: a computational fluid dynamics evaluation.

Irrigation dynamics of syringe irrigation with different needle designs (side-vented, double side-vented, notched) and ultrasonic irrigation in the root canal with internal root resorption were evaluated using a computational fluid dynamics model. A micro-CT scanned mandibular premolar was used for modeling internal root resorption. The needles and the ultrasonic tip were positioned at 2, 4, and 5mm from the working length. The insertion depth and the irrigation model were found influential on the shear stress and the irrigant extension. The extension of the irrigant increased toward 2-5mm from the working length. Ultrasonic irrigation revealed the highest shear stress values regardless of the insertion depth. The shear stress distribution on the resorption cavity walls gradually increased when the needles were positioned coronally. The residence time of the irrigant in the canal was affected by the needle position relative to the internal root resorption cavity and the needle type.

Comparative evaluation of efficacy of different irrigation devices in removal of calcium hydroxide in teeth with simulated internal resorption cavities - An in vitro study.

The aim of this in vitro study was to compare the efficacy of newly developed irrigation systems, i.e., XP-endo Finisher file (XP-endo), EndoActivator (EA), and Endo-Irrigator Plus (EI) with gold standard passive ultrasonic irrigation (PUI) tip and in removal of calcium hydroxide (CH) from single-rooted teeth with artificial simulated internal resorption cavities. One hundred and twenty single-rooted mandibular premolars were decoronated and prepared using the ProTaper Gold system up to F5. Samples were buccolingually sectioned and resorption cavities were prepared. Twenty specimens were served as Group 1 - negative control. In the remaining specimens, CH was delivered and root halves were brought together. Twenty specimens were served as Group 2 - positive control. The remaining specimens were randomly divided into four experimental groups (n = 20), where NaOCl and EDTA were activated using PUI, XP-endo, EA, and EI for 1 min. The remnants of CH were scored and analyzed by employing Kruskal-Wallis H- and Mann-Whitney U-tests. PUI and XP-endo removed more CH than other devices (P < 0.05), showing no significant difference between them. None of the tested systems were able to remove CH completely from resorption cavities. PUI and XP-endo were superior to other tested devices.

Endodontic management of perforating internal resorption in a mandibular molar using sandwich technique

Internal inflammatory root resorption is an uncommon pathology that can progress to the periradicular vicinity. It is frequently asymptomatic and only discovered during a radiological screening. Appropriate and timely diagnosis is extremely crucial in tackling these cases. A perforating internal resorptive cavity in the distal root of the mandibular first molar was successfully managed using a sandwich concept of sectional apical obturation with gutta-percha and Bioceramic sealer followed by the placement of mineral trioxide aggregate in the resorptive cavity.

Строение и места наименьшей устойчивости костно-сухожильных соединений сгибателей пальца лошади

We studied the peculiarities of the structure and functions of bone tendon compounds (enthusis). The subject of the study is a horse. Subject of investigation – places of attachment of tendons of superficial finger flexor, deep finger flexor. Light microscopy, polarization microscopy and biomechanics were used. The general patterns of the structure of enthesis that belong to the fibrous cartilage and fibrous types are established. In the enthesis of the fibrous cartilage type there are zones of tendon, fibrous cartilage, mineralized fibrous cartilage, lamellar bone tissue. Areas of tendon, reticulofibrous bone tissue, lamellar bone tissue were identified in fibrous type enthesis. Biomechanical enthesis of different types are different. In fibrous cartilaginous entesis, the microhardness of tissues changes smoothly, in fibrous – more dramatically. It is shown that the fibrous-cartilaginous enthesis are adapted to dissipate the stresses that arise when the tendon is stretched. Fibrous-type enthesis tightly fix tendons on the bone. The revealed structural and functional features ensure the functional reliability of the entheses. But there are also places of least stability – stress concentration zones. These are the mineralization front, as well as the resorption cavities that occur during the remodeling of mineralized cartilage and subchondral bone. During overloads, they can be injured and lead to the occurrence of enthesopathies.

Comparative evaluation of efficacy of XP Endo Finisher, sonic, and ultrasonic irrigation in removal of calcium hydroxide and subsequent adaptation of gutta percha in simulated internal resorption cavity - An in vitro study

Comparative evaluation of efficacy of XP Endo Finisher, sonic, and ultrasonic irrigation in removal of calcium hydroxide and subsequent adaptation of gutta percha in simulated internal resorption cavity - An in vitro study

Assessment of heat transfer to periodontal tissues and stress distribution in a tooth with simulated internal resorption cavities at different root levels using two thermoplasticized obturation systems – A finite element analysis study

Assessment of heat transfer to periodontal tissues and stress distribution in a tooth with simulated internal resorption cavities at different root levels using two thermoplasticized obturation systems – A finite element analysis study

Evaluation of Debris Removal Efficacy of Conventional Syringe, Irrisafe, XP-endo Finisher File, and Photon-Induced Photoacoustic-Streaming Methods in Teeth with Artificial Internal Resorption Using Two Different Methodologies.

Objective: This study sought to evaluate the effect of conventional syringe irrigation (CSI), irrigation with XP-endo Finisher file (XP-F), passive ultrasonic irrigation (PUI), and photon-induced photoacoustic-streaming (PIPS) methods on dentine debris removal from teeth with simulated internal root resorption (IRR) cavities by using scoring and image analyzing methods. Materials and methods: Chemomechanical preparation of 88 single-rooted sample teeth was completed, they were split longitudinally and IRR cavities were prepared. Simulated debris was placed into the cavities. Four teeth were separated to serve as the negative control group. According to the final irrigation technique, 4 experimental groups were created (n = 20): Group 1, CSI; Group 2, XP-F; Group 3, PUI; and Group 4, PIPS. The amount of remaining debris in the IRR cavities was examined under a stereomicroscope. Analysis was performed using two different methodologies: (1) scoring method and (2) image analyzing method. The data were statistically evaluated by one-way analysis of variance, Kruskal-Wallis, chi-square, and Dunn tests with a significance level set as 5%. Results: In both methodologies, PIPS was found to be significantly more effective than XP-F in terms of debris removal. There was no significant difference between XP-F and PUI (p > 0.05). According to the findings obtained from the image analyzing method, PIPS and PUI groups were not significantly different (p > 0.05). Conclusions: PIPS method can be selected as an irrigation activation methodology in teeth with IRR. Considering the similar results of both evaluation methods, image analyzing programs can be used as an alternative in studies on debris removal.

Bone histology of Broad-snouted Caiman Caiman latirostris (Crocodylia: Alligatoridae) as tool for morphophysiological inferences in Crocodylia

Bone histology is an important tool for the interpretation of life patterns in animals of the past and extant fauna. The crocodylians have been studied as important inferential models for morphophysiological characteristics. We aimed to characterize the osteohistology of captive Caiman latirostris, identifying its microanatomy related to growth rates, ontogeny, and environmental conditions. We analyzed five pairs of humeri (proximal elements of the appendicular skeleton) and ribs (axial skeleton) of females’ caiman. Ribs showed, in general, woven-fibered tissues, with low vascularization and parallel-fibered bone and many resorption and erosion cavities. It presented lines of arrested growth (LAGs) in three individuals, without skeletochronological compatibility. Humeri showed a gradient of woven-fibered to parallel-fibered and lamellar-zonal bone as the individuals aging. We observed compacted coarse cancellous bone (CCCB) and a higher number of LAGs in older specimens. Ribs remodel faster than humerus, showing an intra-individual histovariability. The humeri indicated an evident growth pattern with different ontogeny stages and growth rates in different ages. Fast-growing tissues are uncommon in crocodylians, but basal metabolism and optimal growth conditions can lead to this. Bone histology of C. latirostris shows patterns that can be used as inferential models for extant and extinct groups, but we encourage further studies for a better understanding, under different environmental conditions, such as temperature and food availability.

Skeletochronology and Paleohistology of Hyposaurus rogersii (Crocodyliformes, Dyrosauridae) from the Early Paleogene of New Jersey, USA.

Simple SummaryThe way of life and biology of extinct animals can be inferred from growth marks and microstructures in their fossil bones. Hyposaurus is a genus representative of dyrosaurids, a group of crocodile-like animals that survived the extinction event that killed the dinosaurs but nonetheless has long become extinct. The current study focuses on bone sections from a single individual, extracted from the optimal location in the best bones for such studies. It complements and corrects previous works based on less optimal material, and concludes that the genus was a marine ambush predator rather than a fast-swimming pursuit predator, that the males of the genus grew larger than the females, and that the individual studied was a fully mature 17–18-year-old female.The paleohistology of dyrosaurids is known from a small sample, despite being common fossils and representing a rare lineage of crocodylomorphs that survived the Cretaceous–Paleogene extinction. Their lifestyle has been inferred only from sections of the snout, vertebrae, partial femur, and tibia. To improve this, we conducted a skeletochronological and paleohistological study of midshaft cross-sections of both femora and humeri of a nearly complete Hyposaurus rogersii skeleton. We found lamellar-zonal bone that underwent remodeling, evidenced by resorption cavities and abundant secondary osteons within the primary periosteal cortex. The osteons, mostly longitudinally oriented and arranged in circular rows, often anastomose radially along a linear path, resembling radial rows. The medullary cavity is completely open, lacking trabeculae: endosteal deposition is limited to thin lamellae surrounding the cavity. Analysis of cyclical growth marks and the presence of an external fundamental system indicate the specimen was a fully mature adult 17–18 years of age. Comparison of the skeleton to others suggests sexual dimorphism and that it was female. The open medullary cavity, and no evidence for pachyosteosclerosis, osteosclerosis, osteoporosis, or pachyostosis indicate H. rogersii was not a deep diver or a fast swimmer in the open ocean but a near-shore marine ambush predator.

Efficacy of Laser-Activated Irrigation and Conventional Techniques in Calcium Hydroxide Removal from Simulated Internal Resorption Cavities: Micro-CT Study.

Objective: This study aimed to evaluate the effectiveness of different irrigant-activation techniques for eliminating calcium hydroxide from an internal root canal resorption cavity by using microcomputed tomography (micro-CT). Background: Several techniques and irrigants are inadequate for the complete removal of calcium hydroxide from an internal root resorption cavity. Recently, a few studies have investigated the effectiveness of various methods, but there has been no micro-CT study that compares the effectiveness of photon-induced photoacoustic streaming (PIPS) and shock wave enhanced emission photoacoustic streaming (SWEEPS) techniques. Methods: Seventy single-canal mandibular premolar teeth were selected and divided into seven groups (n = 10) according to the techniques to be used: syringe irrigation (SI), passive ultrasonic irrigation (PUI), EndoActivator (EA), XP-Endo finisher file (XP), Er,Cr:YSGG laser-activated irrigation, PIPS, and SWEEPS. The root canals were instrumented using a rotary system and divided vertically. Internal resorption cavities were created and standardized through diamond burs. Calcium hydroxide was placed into the root canal space. All specimens were evaluated using micro-CT in two different periods. The initial and residual calcium hydroxide volumes in the simulated cavities were calculated. Data were analyzed using a Kruskal-Wallis H test. Results: SWEEPS and PIPS were significantly more effective than EA, Er,Cr:YSGG, PUI, XP, and SI (p < 0.05). There was no significant difference between the SWEEPS and PIPS groups (p > 0.05). SI and XP showed the least effective activity (p < 0.05). Conclusions: The SWEEPS and PIPS techniques were superior to the EA, Er,Cr:YSGG, PUI, XP, and SI techniques. None of the techniques used entirely removed the calcium hydroxide from the resorption cavities.

Efficacy of Passive Ultrasonic Activation in Removing Calcium Hydroxide from Simulated Internal Resorption Cavities at Different Root Regions.

The aim of this study was to evaluate the effect of passive ultrasonic activation on calcium hydroxide removal from simulated internal root resorption (IRR) cavities at different root levels. Sixty mandibular canines were prepared and divided into 3 groups to create IRR cavities at apical, middle, coronal root levels. The cavities filled with calcium hydroxide (CH). Specimens were divided into two subgroups according to the technique used for CH removal: Passive ultrasonic activation (PUA), Classic syringe irrigation (CSI). The cavities were photographed with a stereomicroscope, and percentage of remaining CH was measured using digital image analysis software (Image J). Statistical analysis was performed with two-way ANOVA and post-hoc Duncan tests. PUA removed significantly more CH at apical and middle levels. (p < 0.05) There was no significant difference between PUA and CSI at coronal level. (p > 0.05) In PUA group, the amount of residual CH was the highest at coronal level. (p < 0.05) In CSI group, the amount of residual CH was the highest at apical level. (p < 0.05). None of the tested technique was able to completely remove CH from the simulated IRR cavities. CH was removed better with PUA than CSI at middle and apical root levels. For both techniques, the best results were obtained at middle root level.

Assessment of Fracture Resistance in Teeth with Simulated Perforating Internal Root Resorption Cavities Repaired with Biodentine, Retro MTA and Portland Cement (A Comparative In Vitro Study)

Assessment of Fracture Resistance in Teeth with Simulated Perforating Internal Root Resorption Cavities Repaired with Biodentine, Retro MTA and Portland Cement (A Comparative In Vitro Study)

The consequences of living longer-Effects of an experimentally extended velvet antler phase on the histomorphology of antler bone in fallow deer (Dama dama).

Antlers are periodically regenerated paired cranial appendages of male deer (both sexes in reindeer) that constitute the fastest‐growing bones in the animal kingdom. The annual antler cycle of male deer is linked to testicular activity and largely controlled by seasonal fluctuations of testosterone concentrations in their blood. We studied the effects of an experimental doubling (to eight months) of the velvet antler phase, during which the antlers are covered by skin (velvet), on the histomorphology of antler bone in three adult fallow bucks. Extension of the velvet antler phase in the experimental animals had been caused by administration of the antiandrogen cyproterone acetate (CPA). The distal portions of the antlers from two of the CPA‐treated bucks exhibited partial sequestration of the antler cortex, with the separation plane typically located along the border between cortex and spongiosa. It is hypothesized that this was caused by cortical necrosis due to severe ischemia during later stages of the extended velvet antler phase. In places, new cancellous bone had been deposited on the resorption surface of the spongiosa, indicating a regeneration process. Normal fallow deer antlers (“controls”) from this and a previous study, that is, antlers with a timespan of about four months between onset of new antler growth and velvet shedding, exhibited no or only minor bone remodeling and still contained remnants of calcified cartilage in their distal portions. In contrast, the antlers of the three CPA‐treated bucks showed evidence (secondary osteons and resorption cavities) of marked bone remodeling along their entire length and lacked remnants of calcified cartilage. Our results underscore that the typical histological features of antler bone reflect its short‐lived nature. Antlers are not mechanically loaded during the velvet stage, and it is presently unclear what triggered remodeling activity in the antlers whose lifespan had been experimentally extended.

Influence of 1-Hydroxyethylidene-1,1-Diphosphonic Acid on the Soft Tissue-Dissolving and Gelatinolytic Effect of Ultrasonically Activated Sodium Hypochlorite in Simulated Endodontic Environments.

The addition of Dual Rinse HEDP, an etidronate powder, to a sodium hypochlorite (NaOCl) solution can create a combined single endodontic irrigant with a soft tissue-dissolving and a decalcifying effect, which can replace traditional alternating irrigation with chemically non-compatible solutions. While the short-term compatibility between NaOCl and 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) has been shown, it remains unclear whether ultrasonic activation of a combined NaOCl & HEDP solution immediately reduces the available chlorine and/or renders the NaOCl ineffective in dissolving organic tissue remnants. This was tested in three experiments: (1) direct activation in test tubes in an ultrasonic bath and then the activation by an ultrasonically oscillating tip (IrriSafe) in (2) an epoxy resin model containing a simulated isthmus filled with gelatin, and (3) extracted teeth with simulated resorption cavities filled with soft tissue. The control solutions were physiological saline and 2.5% NaOCl without HEDP. In (1), available chlorine after 30 s of ultrasonic activation (37 kHz) of test and control solution was assessed, as well as shrimp tissue weight loss in direct exposure. In (2) and (3), the ultrasonic tip was driven at 1/3 of full power using the respective unit, and areas of removed gelatin from the isthmus and tissue weight loss were used as the outcomes, respectively. Experiment (1) revealed no negative impact by HEDP on available chlorine (1), while all three experiments showed a highly significant (p > 0.001) synergistic effect, which was not hampered by HEDP, between NaOCl and ultrasonic activation regarding tissue weight loss (1, 3) and dissolution of gelatin (2).

Reprint of: Relationship Between Surface and Inflammatory Resorption and Changes in the Pulp After Replantation of Permanent Incisors in Monkeys

The etiology of surface and inflammatory root resorption after the replantation of incisors was examined in green vervet monkeys. The teeth were examined histologically and histobacteriologically for pulpal healing and root resorption 2 and 8 weeks after replantation. In contrast to surface resorption, inflammatory resorption was related to infected necrotic tissue or an infected leukocyte zone in the root canal. The following theory for surface and inflammatory resorption is presented. Damaged periodontal ligament areas and damaged parts of the root surface are attacked by a resorption process whereby resorption of cementum and dentin may occur. Inflammatory resorption or surface resorption will then occur depending on the pulpal status and the depth of the resorption cavity. If the resorption cavity penetrates the intermediate layer of cementum and contacts dentinal tubules that are in communication with infected necrotic pulp tissue or an infected leukocyte zone, then inflammatory resorption will take place as a result of the diffusion of toxic elements from the pulp canal to the resorption cavity. However, if the resorption cavity is shallow and does not penetrate the intermediate layer of cementum, a tooth that displays similar pulpal changes will elicit only surface resorption because the intermediate layer of cementum will tend to arrest the diffusion of toxic elements. Finally, if the pulp contains vital, inflamed, or noninflamed tissue or if root canal treatment has been performed, surface resorption will occur regardless of the depth of the cavity.

Disturbance of osteonal bone remodeling and high tensile stresses on the lateral cortex in atypical femoral fracture after long-term treatment with Risedronate and Alfacalcidol for osteoporosis

An 83 year-old Japanese woman complained of left lateral thigh pain following a low-energy fall 4 months prior to admission. She had been treated for osteoporosis with Risedronate and Alfacalcidol for the previous five years. She was diagnosed with an atypical femoral fracture (AFF) according to the American Society for Bone and Mineral Research (ASBMR) Task Force revised criteria. Radiographs revealed cortical thickening and a transverse radiolucent fracture line in the lateral cortex of the shaft. MRI showed a high intensity signal on the T2WI image 1 cm long in the lateral cortex. The patient had normal levels of bone resorption and formation biomarkers except for low 25(OH) Vitamin D. Double fluorescent labeling was done preoperatively.Due to significant bowing, a corrective osteotomy and intramedullary nailing were performed, and the resected bone wedge was analyzed by bone histomorphometry. Three ground sections of the lateral cortex at the fracture site showed many and large pores, with or without tetracycline labeling. Histomorphometric assessment was done on intracortical pores, classified by a novel criteria, only to assess size of the pores to know prolonged osteoclastic activity and its characteristics of inner surfaces to assess whether bone formation has been occurring or not in labeling period in remodeling cycle, and coalition of multi-pores. Increased size with widespread variation of pores suggested prolonged osteoclastic activity in the reversal/resorptive phase. Bone labeling showed lamellar bone on the endocortical surface.We hypothesize that the case had developed from a regional disturbance of osteonal remodeling in the lateral cortex, in which accumulated microcracks might have initiated a resorption process resulting in resorption cavities, i.e., pores, which became larger due to prolonged activity of secondary osteoclasts. Various sized pores could form lamellar bone, still forming at the time of biopsy, some had formed lamellar bone, but stopped to form before labeling and not to start to form at all, probably due to incomplete coupling. Endocortical lamellar bone might had started to resorbed to smooth off endocortical surface, followed by formation of lamellar bone. The endocortical bone formation was assessed and its formation period is about 2.7 years.A finite element analysis using preoperative CT data revealed high tensile stresses on the lateral aspect of the femur. Histomorphometric results suggest that there might be more pores in the tensile area than the compressive area. These findings may subsequently connect accumulation of microcracks, an increase of size and number of pores and coalition and subsequent fracture in the lateral cortex.

Evaluation of Different Root Canal Obturation Techniques in Internal Root Resorption of Three-Dimensional Printed Teeth Manufactured Using Computer Software.

The objective of this study was to evaluate and compare the filling ability of various root canal obturation techniques on the internal root resorption (IRR) cavities of replicated tooth samples manufactured using computer software and a three-dimensional (3D) printer. Orthographic images and root structures of a healthy upper maxilla central incisor in determined volumes and sizes were drawn as a prototype with the aid of computer software. Using the same software, an IRR defect was also modeled. These two images were then transferred to the AutoDesk Fusion 360 3D modeling program (AutoDesk, San Rafael, CA) for meshing. Afterward, the tooth model was transferred to a 3D modeling and prototyping program (RhinoCeros 3D; Robert McNells & Assoc., New York) and printed on a 3D printer. Eighty replicas with IRR were manufactured and divided into four groups (n = 20 per group) according to the obturating techniques as follows: Group 1: Cold lateral compaction (CLC), Group 2: Core Carrier System (GuttaCore), Group 3: Injectable Cold Filling (GuttaFlow® BioSeal), and Group 4: Continuous Wave Obturation System (Elements Free). After root canal filling, replicas were scanned with a high-resolution micro-computed tomography system (SkyScan 1172; Bruker-microCT, Kontich, Belgium), data regarding voids (unobturated areas) inside the IRR defects were statistically analyzed using nonparametric Kruskal-Wallis tests. A pairwise comparison between the tested groups showed that Groups 3 and 4 had significantly fewer voids compared with Groups 1 and 2 in IRR defects (p < 0.05). Group 1/Group 2 and Group 3/Group 4 had similar results in terms of voids and there were no statistically significant differences (p > 0.05). The injectable cold filling system (GuttaFlow BioSeal) and the injectable continuous wave obturation system (Elements Free) successfully obturated the pathological IRR irregularities when compared with CLC and core carrier (GuttaCore) systems.

Bone remodeling stages under physiological conditions and glucocorticoid in excess: Focus on cellular and molecular mechanisms

This review provides a rationale for the cellular and molecular mechanisms of bone remodeling stages under physiological conditions and glucocorticoids (GCs) in excess. Remodeling is a synchronous process involving bone resorption and formation, proceeding through stages of: (1) resting bone, (2) activation, (3) bone resorption, (4) reversal, (5) formation, (6) termination. Bone remodeling is strictly controlled by local and systemic regulatory signaling molecules. This review presents current data on the interaction of osteoclasts, osteoblasts and osteocytes in bone remodeling and defines the role of osteoprogenitor cells located above the resorption area in the form of canopies and populating resorption cavities. The signaling pathways of proliferation, differentiation, viability, and cell death during remodeling are presented. The study of signaling pathways is critical to understanding bone remodeling under normal and pathological conditions. The main signaling pathways that control bone resorption and formation are RANK / RANKL / OPG; M-CSF – c-FMS; canonical and non-canonical signaling pathways Wnt; Notch; MARK; TGFβ / SMAD; ephrinB1/ephrinB2 – EphB4, TNFα – TNFβ, and Bim – Bax/Bak. Cytokines, growth factors, prostaglandins, parathyroid hormone, vitamin D, calcitonin, and estrogens also act as regulators of bone remodeling. The role of non-encoding microRNAs and long RNAs in the process of bone cell differentiation has been established. MicroRNAs affect many target genes, have both a repressive effect on bone formation and activate osteoblast differentiation in different ways. Excess of glucocorticoids negatively affects all stages of bone remodeling, disrupts molecular signaling, induces apoptosis of osteocytes and osteoblasts in different ways, and increases the life cycle of osteoclasts. Glucocorticoids disrupt the reversal stage, which is critical for the subsequent stages of remodeling. Negative effects of GCs on signaling molecules of the canonical Wingless (WNT)/β-catenin pathway and other signaling pathways impair osteoblastogenesis. Under the influence of excess glucocorticoids biosynthesis of biologically active growth factors is reduced, which leads to a decrease in the expression by osteoblasts of molecules that form the osteoid. Glucocorticoids stimulate the expression of mineralization inhibitor proteins, osteoid mineralization is delayed, which is accompanied by increased local matrix demineralization. Although many signaling pathways involved in bone resorption and formation have been discovered and described, the temporal and spatial mechanisms of their sequential turn-on and turn-off in cell proliferation and differentiation require additional research.

Age-related changes of the histological structure in the limb bones of the domestic fowl

To assess the possibility of using the bird bone tissue as a recording structure, the histomorphological parameters of the bone tissue of laying hens of the lohman brown cross from the Kirov region (9 females and 1 male) aged from 1 month to 7.5 years were investigated. The comparison of the cross-sections of the humerus and femur, the phalanx of the toe and tibiotarsus of a 6-year-old individual revealed that tibiotarsus is the least susceptible to resorption. For further research in 7 individuals, this bone was divided into 3 sections (T1, T2 and T3), for each of which the description and measurement of the microstructure of the cross sections was carried out. It was revealed that the process of resorption of the periosteum begins at 2.5 years of age with the appearance of primary osteons. At the age of 3.5 years and later they penetrate into all layers of the periosteum, locating in chains between the lines of arrested growth. At 4.5 years of age, secondary osteons appear in the place of the primary ones, and areas of resorption are formed at the intersection of the Haversian and Volkmann canals. At the age of 5.5 years the medullary bone disappears from the bone cavity, rounded cavities filled with centripetal deposition of new bone tissue at the edges appear within the resorption sites. At the age of 6-7 years, bone tissue degeneration occurs, when the small cavities enlarge and merge into large resorption cavities, up to the complete resorption of the mesost. In the distal part of tibiotarsus (T3), a prolonged apposition of the layers of the periosteum and the latest resorption were recorded. The increase of the thickness of the periosteum and a decrease in the density of the osteon population was revealed by the morphometry of cross sections of the center of diaphysis. The sites of tibiotarsus where the age of females corresponds to the lines of growth layer of the periosteum were determined. The sites with additional lines of the arrested growth were demarcated. It was concluded that the periosteal layer of the domestic fowl tibiotarsus in the distal and proximal sites are suitable as a recording structure.

Dentinal Lesions in Dogs with Dental Calculus

Histopathological changes in tooth structures in dogs with calculus have not been described. The aim of this study was to evaluate the frequency of various histopathological changes in the dentine of teeth that had been surgically extracted from dogs with calculus. Data including breed, sex, age, reason for tooth extraction and dental history were obtained for each animal. A total of 158 teeth (45 incisors, 31 canines, 35 premolars and 47molars) with calculus were extracted from 74 dogs of various ages and breeds. The teeth were decalcified, processed in paraffin wax and stained with haematoxylin and eosin for histopathological analysis. Of the 158 analysed teeth, 71 had dentinal changes, including 45 with external resorption cavities, 11 with osteodentine, six with internal resorption cavities, four with tertiary dentine, four with dentinal degeneration or fragmentation, and one with predentine degeneration or fragmentation. Canine teeth were the least commonly affected. Areas of dentinal degeneration or fragmentation unrelated to resorption cavities were only seen in the incisor and molar teeth. Dentinal changes and their frequencies were similar among the incisor, premolar and molar teeth. The presence or extension of dental calculus was not associated with the type or frequency of dentinal changes.