Epithelial remnants in the crestal periodontium of the dog

Abstract The purpose of this study was to access the effect of age on the epithelial remnants (EPRs) of the crestal periodontal tissues of beagle dogs. The material consisted of 10 beagle dogs; 5 were 1-year-old (young dogs) and 5 were 9-years-old (old dogs). All animals belonged to the same dog colony and had been raised under similar conditions. Since birth, the dogs had been subjected to professional prophylaxis 4 ×/per year. Biopsies were obtained from the man-dibular 3rd and 4th premolar regions and were prepared for histologic analysis. 2 areas, (1) the supracrestal region and (2) the marginal periodontal ligament region, were identified. The supracrestal region was further divided into 4 compartments of equal height. The histologic parameters studied included: the (i) number of EPRs/mm root length; EPR frequency; (ii) size of EPR; (iii) distance between the root surface and the EPR; (iv) distance between the alveolar bone and the EPR; (v) epithelial cell area. The supracrestal region (total and various compartments) of old dogs harbored significantly fewer yet larger EPRs than epithelial remnants of young dogs. Similarly, the EPR's of the periodontal ligament region were significantly larger and closer to the root surface in old dogs compared to young dogs. No difference was noted in the cell area of EPRs between young and old dogs for cither region. Epithelial remnants of the supracrestal region in both groups of dogs were somewhat more frequent, larger and positioned further from the root surface than the EPRs of the periodontal ligament region. Within the 4 compartments of the supracrestal region, the EPR frequency was less and the EPR size larger in old than in young dogs, with the most dramatic difference occurring in the most coronal compartment. It was concluded that EPRs are a normal constituent of the periodontal tissues of the permanent dentition of the beagle dog which undergo distinctive changes with age.     

The effect of progressive tooth mobility on destructive periodontitis in the dog

Abstract. The aim of the present study was to assess the influence of traumatic forces causing a gradually increasing tooth mobility on an ongoing destructive periodontitis.
The experiments were performed in five dogs fed a diet which permitted dental plaque accumulation. Periodontal breakdown was induced around the mandibular third and fourth premolars (₄P, ₃P and P₃, P₄) by the placement of plaque retention ligatures around the neck of the teeth. After 330 days, when approximally 50 % of the supporting tissues had been lost, mucoperiosteal flaps were raised around the four premolars and notches prepared in the buccal root surfaces at the marginal termination of the alveolar bone. The notches served as landmarks for measurements to be made in histological sections. The flaps were resutured and new plaque retention ligatures placed around the roots of all four teeth.
One week later (Day 0), P₃ and P₄ (test teeth) were subjected to jiggling forces in a bucco-lingual direction with the use of an elevator. The jiggling procedure which had a duration of 30 seconds, was repeated on Days 4, 8, 12 and 16, and was guided in such a way that the tooth mobility gradually increased during the experimental period. The animals were sacrificed on Day 26, and sections of ₄P,₃P and P₃, P₄ were prepared for light microscopic examination.
The results of the study demonstrated that jiggling forces, resulting in a progressive increase of tooth mobility, mediated an enhanced rate of destruction of the supporting apparatus in dogs with an ongoing process of periodontal tissue breakdown.     

Experimental periodontal breakdown in the dog

abstract – This paper describes a method for inducing rapidly progressing and reproducible periodontal lesions around selected teeth in dogs. The experiments were performed on 10 beagles which were fed a diet favoring gross formation of plaque. Approximately 1 mm of the marginal alveolar bone around ₄P and P₄ was removed and a notch prepared in the root. A ligature of cotton floss was placed around ₄P and P₄ at the cemento-enamel junction. Radiographs and sections prepared 230 d later revealed that a progressive breakdown of the periodontal tissues had occurred. The average bone loss was 2.4 mm and the distance between the apical cells of the pocket epithelium and the notch was 854μm.     

Periodontal ligament stresses in the initiation of occlusal traumatism

Mechanical stresses in the periodontal ligament which help initiate the lesion of occlusal trauma have been difficult to evaluate. The purpose of this study was to use a mathematical system (finite element analysis) to calculate principal periodontal ligament stresses in primary and secondary occlusal trauma. Maxillary central incisors were modeled in periodontal tissues representing four levels of bone support. Models were partitioned and subjected to three simulated functional loads. Stresses were calculated at multiple nodes in the periodontal ligament adjacent to root and bone. Results showed areas of greatest compressive stress near the alveolar crest and in the apical one-half of the root for all loads at all bone levels. Stress curves correlated well with the histologic lesion of occlusal trauma. Centric contact loads (P₃) consistently produced less ligament stress than protrusive contact (P₁). Reduction of alveolar bone height had little effect on the degree of periodontal ligament stress until six millimeters (60%) of bone support had been lost. Finite element analysis provides a convenient model for the study of the mechanical component of occlusal traumatism.     

Destructive periodontal disease in healthy children.

This study determined the prevalence of destructive periodontal disease affecting the deciduous dentition among otherwise healthy subjects, who were diagnosed with juvenile periodontitis (JP) in their permanent dentitions. There were 4,757 subjects in this retrospective, cross-sectional study. Diagnosis of JP was based on age (< or = 15 years), negative medical history, and radiographic evidence of arc-shaped alveolar bone loss. The study population was one-third white and two-thirds black and the male/female ratio was 1:1, reflecting the general patient population. The prevalence among whites was 0.3%, with a female/male ratio 4:1; whereas among blacks the prevalence was 1.5%, with a female/male ratio approximately 1:1. Among the black JP subjects with radiographs of the mixed dentition, 85.7% presented evidence of bone loss, and of those with radiographs of the deciduous dentition, 71.4% had discernible alveolar bone loss. This study suggests that JP is much more prevalent in blacks and that it does indeed occur in the prepubertal years affecting the deciduous as well as the permanent dentitions in otherwise healthy children. These data imply the importance of including a periodontal evaluation in the examination of children, using the periodontal probe and radiographs sufficient to adequately view the alveolar bone.     

Development of deciduous and permanent dentitions in the upper jaw of the house shrew (Suncus murinus)

The diphyodont tooth replacement in mammals is characterized by a single replacement of a deciduous dentition by a permanent dentition. Despite its significance in mammalian biology and paleontology, little is known about the developmental mechanisms regulating the diphyodont replacement. Because the mouse never replaces its teeth, this study used the house shrew, Suncus murinus, as a model to investigate the control of the diphyodont replacement of a deciduous dentition by successions and additions of permanent teeth. Using morphological and gene expression analyses of serial sections, we have demonstrated the development of the upper dentition of the house shrew. In this species, the deciduous tooth germs are formed but soon become vestigial, whereas the successional and accessional (molar) germs are subsequently formed and developed. There are distinct Shh expression domains in the deciduous, successional, and accessional tooth germs, and those of the latter two germs are identified from the appearance of their primary enamel knots. The developmental sequence of tooth germs in the house shrew indicates that two adjacent primary enamel knots of the successional and accessional germs do not develop simultaneously, but with a constant time lag. We suggest that this mode of tooth succession and accession can be explained by a sequential inhibitory cascade model in which the timing of initiation and the spacing of tooth development are determined by the inhibition from the primary enamel knots of developmentally preceding adjacent tooth germs.     

The House Shrew,Suncus murinus,as a Model Organism to Investigate Mammalian Basal Condition of Tooth Development

Mammalian dentition is characterized by regional differentiation into incisors, canines, premolars and molars in each jaw quadrant (heterodonty), and tooth replacement once during the lifetime (diphyodonty). Despite their significance in various research fields, little is known about the developmental mechanisms regulating tooth type (class) determination and diphyodont tooth replacement. The mouse, the most popular laboratory animal, is not appropriate for the investigation of heterodonty and diphyodonty, because of its highly specialized dentition. The house shrew, Suncus murinus, has been suggested to be a potentially excellent model organism to study the mammalian basal condition of tooth development. Using three-dimensional (3-D) reconstructions of dental epithelium from serial histological sections, and Sonic hedgehog (Shh) expression patterns, we have precisely located the tooth-forming regions of all tooth types in the developing jaws of the house shrew. The incisor region in the upper jaw is found to extend across the boundary between the frontonasal and maxillary processes. The molar-forming region is later added distal to the first demarcated tooth-forming regions by secondary extension of the dental lamina. Furthermore, we have elucidated the replacement pattern of the deciduous dentition by succession and addition (accession) of the permanent teeth in the house shrew. On the basis of new knowledge on tooth development in the house shrew, we discuss the developmental mechanisms regulating tooth type determination and diphyodont tooth replacement, and consider future prospects in the field.     

Periodontal ligament areas and occlusal forces in dentitions restored with cross-arch bilateral end abutment bridges

The aim of the present investigation was to find out to what extent the magnitudes of chewing and biting forces in dentitions restored with cross-arch bilateral end abutment bridges are correlated to the areas of the periodontal ligament supporting the abutment teeth. 12 subjects whose dentitions had been periodontally treated and prosthetically restored participated in the study. The chewing and biting forces were measured in various parts of as well as over the entire dentition simultaneously using 4 strain gauge transducers bilaterally placed in pontics of the posterior (first molar/second premolar) and anterior regions. Based on calculations of the periodontal ligament areas, a new periodontal support index, PSIL, is introduced. This index expresses the relation between the total remaining periodontal ligament area supporting the bridge abutments and total maximal periodontal ligament area if all teeth were preserved as abutments. It is compared with the index of Ante, PSIA, which expresses the relation between the total remaining periodontal ligament area of all abutments and the total maximal periodontal ligament area of all replaced teeth. Within the present group of subjects, PSIL varied from 10 to 44% and PSIA from 17 to 118%. Based on the results of the correlation analyses, it is suggested that in dentitions restored with cross-arch bilateral end abutment bridges, the magnitude of the chewing forces is positively correlated to the areas of the periodontal ligament supporting the bridge abutments, whereas the periodontal ligament areas have no influence on the comparatively larger biting forces. The relevance of the 2 periodontal support indices and the clinical implications of the results of the study are discussed.     

Localized Aggressive Periodontitis Treatment Response in Primary and Permanent Dentitions

Background: The comparative treatment response of children and young adults with localized aggressive periodontitis treatment (LAgP) affecting primary and permanent dentition is unknown. The objective of this study is to evaluate the influence of non‐surgical periodontal therapy with adjunctive systemic antibiotics on the clinical outcome of children and young adults with primary versus permanent dentition affected by LAgP. Methods: A cohort of 97 African American participants aged 5 to 21 years (30 males and 67 females; 22 primary and 75 permanent dentitions affected) diagnosed with LAgP were included. Patients presented with no significant medical history. All patients underwent periodontal therapy, which consisted of full‐mouth mechanical debridement at baseline and the 3‐, 6‐, and 12‐month appointments. Additionally, all patients were prescribed a 1‐week regimen of systemic antibiotics at the initial appointment. Clinical parameters were analyzed, including probing depth, clinical attachment level (CAL), bleeding on probing, and percentage of visible plaque. Results: Overall, periodontal therapy was found to be effective in improving the clinical outcomes of both primary and permanent dentitions. Although baseline CALs were similar between the groups, the reduction in mean CAL at 3, 6, and 12 months and reduction in percentage plaque at 3 months were significantly greater in primary dentition compared with permanent dentition. Conclusions: Non‐surgical therapy with systemic antibiotics is effective for LAgP in both primary and permanent dentitions. A greater reduction in CAL in LAgP of primary dentition may suggest that younger children may carry a greater propensity for positive treatment outcomes and healing potential compared with children/young adults with permanent dentition.     

The Carabelli trait in Australian Aboriginal dentition

Over 80 per cent of the subjects showed some form of the character in the deciduous dentition, about 10 per cent having cusps; in the permanent dentition, about 70 per cent of the subjects had the character, 20 per cent showing cusps. Sexual dimorphism was not evident in the deciduous dentition but, in the permanent dentition, the character was more common in males who also showed a higher degree of expression than females. Generally, the trait occurred bilaterally with symmetrical expression in both dentitions. Although the character was present in the deciduous dentition but not the permanent in a number of subjects, the reverse situation was rare. Comparisons between siblings of individuals with the character and siblings of individuals from the general population provided some evidence of a genetic basis to the character, but its heritability is probably low. Variations in phenotypic trait expression between sides, sexes and dentitions probably reflect the interplay between environmental influences and the timing of developmental processes.     

Difference in the prevalence of enamel alterations affecting central incisors of children with complete unilateral cleft lip and palate.

OBJECTIVE: To evaluate the prevalence of enamel alterations affecting the deciduous and permanent central maxillary incisors of children with complete unilateral cleft lip and palate and to verify their characteristics. DESIGN: Cross-sectional. SETTING: Hospital for Rehabilitation of Craniofacial Anomalies-University of S?o Paulo, Bauru, S?o Paulo, Brazil. PATIENTS: A sample of 90 patients attending the Hospital for Rehabilitation of Craniofacial Anomalies, presenting with complete cleft lip and palate, of both genders, ages 2 to 11 years old. METHODOLOGY: The buccal surfaces of the maxillary central incisors of patients were analyzed for observation of the presence of enamel defects, their type, number, and location. The prevalence of defects was compared between deciduous and permanent teeth and between the incisors at the cleft and noncleft sides. RESULTS: There was a higher frequency of defects among incisors on the cleft side for both deciduous and permanent dentitions compared with the noncleft side (p < .05); the permanent central incisor was more frequently affected than the deciduous. Evaluation of the types of defects for both incisors in both dentitions demonstrated a homogeneous distribution, except for a lower proportion of yellow opacity in the permanent dentition on the cleft side. In general, the most affected area in all dentitions was the incisal third. CONCLUSION: The prevalence of enamel alterations affecting incisors adjacent to the cleft was higher than for incisors on the noncleft side. This difference also was present in the permanent dentition.     

Periodontal ligament areas and occlusal forces in dentitions restored with cross-arch unilateral posterior two-unit cantilever bridges

This investigation was undertaken in order to analyse to what extent the magnitudes of chewing and biting forces in dentitions restored with cross-arch unilateral posterior two-unit cantilever bridges are correlated to the area of the periodontal tissue supporting the abutments. 12 subjects, whose dentitions were periodontally treated and prosthetically restored, participated in the study. The chewing and biting forces, simultaneously measured in various parts of, as well as over the entire dentition, were correlated to the periodontal ligament areas of the abutments supporting the bridge constructions. A strong positive correlation (r = 0.83; P less than 0.01) was found between the total remaining periodontal ligament area and the mean total chewing force. A positive correlation (r = 0.57; P = 0.05) was also found between the local remaining periodontal ligament area of the posterior end abutment tooth and the local chewing force in that region. No positive correlation was found between the amount of periodontal tissue support and the magnitude of the forces developed during biting with maximal strength in habitual occlusion either totally or locally, although there was a strong tendency (r = 0.54; 0.6 greater than P greater than 0.5) towards decreasing total maximal bite force with decreasing total remaining periodontal ligament area. A strong positive correlation (r = 0.74; P less than 0.01) was found on the end abutment side between the local remaining periodontal ligament area of the end abutment tooth and the local forces in that region during biting with maximal strength over a limited area at a time.(ABSTRACT TRUNCATED AT 250 WORDS)     

Classification and prevalence of enamel opacities in the human deciduous and permanent dentitions

A reproducible classification of enamel opacities which is generally applicable for use in clinical investigations was used to determine the prevalence of defects in both deciduous and permanent dentitions in low-fluoride areas; 303 children aged 6 yr and 1214 children aged 13–14 yr were examined. Almost one third of them had enamel opacities in the deciduous dentition, and over 80 per cent showed defects in the permanent dentition. Horizontal white lines in the enamel of permanent teeth, stated to be pathognomic of fluoride-induced enamel changes, were found in 29 children (2.4 per cent). All the children had lived in areas where the drinking water contained less than 0.26 parts/10⁶ fluoride, and none had received fluoride supplementation. The classification used was not based on a presumed aetiology of enamel opacities and could therefore be used to compare prevalence in fluoride-supplemented and low-fluoride areas.     

Histopathology of artificial periodontal defects in beagle dogs before and after ligature removal

The aim of the resent study was to investigate the histopathological characteristics of artificial periodontal defects before and after removal of ligatures. The defects were created in 12 young adult beagle dogs using cotton floss ligatures. The supracrestal dentogingival fibres were dissected around 6 lower premolars (₂P₂, ₃P₃, and ₄P₄) after which closely adapted copper bands were cemented to the teeth. After 3 weeks these copper bands were replaced by subgingival cotton floss ligatures which were left in place for a further 11 weeks. The placement of ligatures around the different teeth and their removal prior to sacrifice was scheduled to provide histological observations of the periodontal defects both with ligatures in situ, and 1 day and 1, 3, 7, 15, or 31 weeks after their removal.
Defects with ligatures in situ showed histopathological characteristics of advanced chronic periodontitis. Removal of the ligatures and the subsequent production of a notch (to mark the bottom of the pocket) resulted initially in an exacerbation of the inflammatory process but 3 weeks after ligature removal, a distinct decrease in size of the infiltrated connective tissue (I. C. T.) could be observed especially in the deeper part of the lesion. The tissues of the periodontium showed signs of repair whack became more pronounced with time. There was no indication that the lesion had become progressive in the remaining period of 7–31 weeks after ligature removal.
It is concluded that the maintenance of the established lesion is dependent on the persistence of subgingival plaque containing ligatures.     

Total impaction of deciduous maxillary molars: two case reports

AIM: The purpose of this report is to present two cases of totally impacted maxillary deciduous molars, considered a rarity in dental practice. BACKGROUND: Primary tooth impaction is quite rare during the development of primary dentition. Various factors contribute to the impaction of a deciduous tooth, including anklyosis, congenitally missing permanent teeth, defects in the periodontal membrane, trauma, injury of the periodontal ligament, precocious eruption of the first permanent molar, defective eruptive force, or a combination of these factors. REPORTS: Case #1: An 18-year-old male presented with a complaint of spontaneous repetitious pain in the maxillary right premolar region. The maxillary right second premolar was clinically absent. Panoramic and periapical radiographs revealed an impacted second premolar close to the inferior wall of the maxillary sinus and an impacted deciduous molar deeply embedded in bone within the maxillary sinus. Case #2: A 14-year-old girl presented with a complaint of crowding of the maxillary teeth. The maxillary right second premolar and the maxillary permanent canines were clinically absent. A panoramic radiograph revealed an impacted maxillary right second premolar and an impacted deciduous molar embedded within bone close to the inferior wall of the maxillary sinus. SUMMARY: The total impactation of deciduous teeth is a rare condition, and few cases have been reported in the literature. The condition generally affects the mandibular second deciduous molar and the maxillary first deciduous least often. In this paper, two cases of totally impacted maxillary deciduous molars are reported.     

Periodontal response to long-term abuse of the gingival attachment by supracrestal amalgam restorations

The combined length of the supracrestal connective tissue attachment and the junctional epithelium is referred to as the "biologic width". The long-term (1-year) effect of complete violation of the supracrestal connective tissue attachment was examined in beagle dogs. Full thickness periodontal flaps were elevated, exposing the buccal bony crests of the maxillary and mandibular canines of 3 beagle dogs. The roots of the experimental teeth were planed and class V cavities were prepared. The apical border of each cavity was located at the alveolar bone crest. The cavities were restored with amalgam and the flaps were repositioned and sutured. In the control sites, a notch was prepared at the CEJ and the distance between the notch and the bony crest was measured. The dogs were sacrificed 57 weeks after the operation and the experimental and control sites prepared for histologic analysis. Every 5th section was examined and measurements were taken of the amount of gingival and bone recession, the length of the connective tissue and the epithelial attachment. Control sites healed uneventfully. Gingival recession averaged only 0.5 mm; bone loss was minimal and averaged 0.15 mm. The combined length of the supracrestal connective tissue and epithelial attachment measured 4.47 mm. In experimental sites, the gingiva receded 3.16 mm on average. Moderate bone loss (mean = 1.17 mm) was noted, but no signs of bone resorption were seen at the time of sacrifice. After bone loss, root surfaces which were previously attached to alveolar bone by periodontal ligament were mainly (0.90 mm) attached to connective tissue.(ABSTRACT TRUNCATED AT 250 WORDS)     

Enhanced gingivitis in the deciduous and permanent dentition An experimental study in the dog

The aim of the experiment was to analyze the reaction of the marginal gingival tissues to 21 days of plaque formation on buccal tooth surfaces in the deciduous and permanent dentition of beagle dogs. In order to enhance the formation of plaque, the buccal surfaces of the experimental teeth were coated with a composite filling material. 5 beagle dogs were used. The animals were monitored during 2 periods, called period A (42 days during the deciduous dentition) and period B (42 days during the permanent dentition). The dogs were 10 weeks old at the initiation of period A. Following 3 weeks of plaque control, a groove was prepared into the enamel of the buccal surfaces of the mandibular right 3rd (03P) and 2nd (02P) premolars. A cotton ligature was subsequently attached to the groove using an enamel/etch-technique and a composite filling material. The groove and the ligature did not interfere with the gingival margin but the composite material extended into the subgingival niche. The plaque control measures were abandoned. The animals formed plaque during the following 21 days. A clinical examination was performed and subgingival bacteria sampled on day 21. Moreover, biopsies were harvested from the 03P and 02P tooth regions. The biopsies were prepared for histometric and morphometric analyses. A 2nd plaque control regimen was initiated. Period B started when the dogs were 15 months old. Following 3 weeks of enhanced plaque control, a cotton ligature was attached as described above at the buccal surfaces of the mandibular left 3rd (P3) and 4th (P4) premolars.(ABSTRACT TRUNCATED AT 250 WORDS)     

Autoradiographic study of 3H-proline incorporation by rat periodontal ligament, gingival connective tissue and dental pulp

The rates of ³H-proline incorporation by the rat periodontal ligament, the gingival connective tissue and the dental pulp were studied by autoradiography. The rate of ³H-proline incorporation by the periodontal ligament was 2.8 times higher than by the gingival connective tissue and 5 times higher than by the dental pulp. These differences were significant (p > 0.01). The pattern of ³H-proline incorporation by the periodontal ligament was significantly different (p > 0.01) from that by the gingival connective tissue and the dental pulp. The latter two tissues exhibited a similar pattern of ³H-proline incorporation. The ratio of the rates of ³H-proline incorporation by the three tissues did not correlate with the ratio of the cellular densities in the same three tissues.     

Periodontal manifestation of leukocyte adhesion deficiency type I

BACKGROUND: Leukocyte adhesion deficiency type I (LAD-I) is an autosomal recessive immunodeficiency disorder characterized by defects in the integrin receptors of white blood cells that lead to impaired adhesion and chemotaxis. Affected patients are susceptible to recurrent bacterial and fungal infections, impaired pus formation, delayed wound healing, and periodontitis. METHODS: A case of generalized advanced periodontal destruction of the permanent and deciduous dentition in a young Jordanian girl with a severe phenotype of LAD-I is presented in this report. The medical diagnosis was made based on the characteristic clinical and laboratory findings, in particular the total absence of CD18, CD11b, and CD11c as determined by flow cytometry sorting. RESULTS: Periodontal findings in this patient include the early onset of the disease, which affected the primary teeth and permanent dentitions, the intense redness and inflammation of the gingiva, and the rapid periodontal destruction that seems refractory to conventional non-surgical periodontal therapy. CONCLUSION: This report emphasizes the importance of the differential diagnosis of severe immunodeficiency disorders in children and adolescents and mandates the importance of combined care by medical and dental practitioners to prevent tooth loss and control oral infection.