Periodontal ligament tissue reactions to trauma and gingival inflammation

Abstract The aims of the present study were to analyze (i) which tissue changes may occur in the zone of co-destruction to better understand why trauma from occlusion may induce additional attachment loss, and (ii) whether changes occur in the periodontal ligament tissue when an inflammatory lesion (ICT) approaches the periodontal ligament space. 16, 1-year-old beagle dogs, were selected and divided into 2 groups, group A and group B, consisting of 6 and 10 dogs, respectively. In group A, on day 0. a bucco-lingual jiggling type movement was induced resulting in increasing tooth mobility at P₃ (test tooth) by the application of an orthodontic elastic which traversed the buccal surface of the crown of the test tooth. The elastic was exchanged either in a buccal or in a lingual position 2x a week during a 3-month period. ₃P served as non-jiggled control tooth. Tooth mobility measurements were recorded on days 0, 30, 60, 90. A plaque control regimen was maintained until the end of the experiment (day 90). On day 90, biopsies including P₃ and ₃P were harvested. The dogs representing group B, were divided into 2 subgroups of 5 each, group BI and group BII. On day 0, a 4-month period of experimental periodontal tissue breakdown was initiated by placing cotton floss ligatures submarginally around the mandibular fourth premolars (₄P₄) in group BI and around the mandibular third premolars (₃P₃) in group BII. All ligatures were exchanged, replaced 1X every month, and on day 120 permanently removed. On the same day, biopsies included ₄P₄ were harvested. Following supragingival debridement ₃P₃ were allowed to accumulate plaque until the end of the study (day 225). On this occasion, biopsies including ₃P₃ were harvested. The results of the histological measurements revealed that in the most coronal portion of the periodontal ligament of teeth exhibiting increasing mobility, there was an increased width, a reduced % tissue volume of collagen, and an increased volume of vascular structures and leukocytes. Furthermore, the number of osteoclasts bordering this portion of the alveolar bone was increased and the number of collagen fibers inserting into the root cementum and into the alveolar bone was reduced. It was also demonstrated that in teeth with normal mobility, the position of the gingival ICT failed to influence the composition of the tissue within the coronal portion of the periodontal ligament.     

Histochemical demonstration of activity of acid phosphatase and beta-glucuronidase in bovine incisor tooth germs

Activity of acid phosphatase and beta-glucuronidase was shown in bovine preodontoblasts and preameloblasts prior to the onset of secretion. In the preameloblasts the rather weak reaction consisted of small discrete granules dispersed in the cytoplasm apical, lateral, and proximal to the nucleus. After initiation of enamel formation, a change in localization and intensity of the colored reaction product was observed in the ameloblasts. The activity appeared stronger and was restricted to a narrow zone just apical to the nucleus. It is proposed that the acid hydrolases in the tooth forming cells are located to the Golgi complex. The differences in activity of acid hydrolases between bone and tooth forming cells are expounded.     

How may stressful experiences contribute to the development of temporomandibular disorders?

Temporomandibular disorders (TMD) comprise the most common cause of chronic facial pain conditions, and they are often associated with somatic and psychological complaints including fatigue, sleep disturbances, anxiety, and depression. For many health professionals, the subjectivity of pain experience is frequently neglected even when the clinic does not find any plausible biologic explanation for the pain. This strictly biomedical vision of pain cannot be justified scientifically. The purpose of this study is to demonstrate, by original articles from the literature and recent studies conducted in our own laboratory, the biological processes by which psychological stress can be translated into the sensation of pain and contribute to the development of TMD. The role of the hypothalamic–pituitary–adrenal axis, the serotoninergic and opioid systems in the pathogenesis of facial pain is exposed, including possible future therapeutic approaches. It is hoped that knowledge from apparently disparate fields of dentistry, integrated into a multidisciplinary clinical approach to TMD, will improve diagnosis and treatment for this condition through a clinical practice supported by scientific knowledge.     

A histomorphometric study of alveolar bone modeling and remodeling under experimental anaemia and polycythaemia in rats

Alveolar bone is the least stable of the periodontal tissues, because it is subjected to continuous modeling and remodeling. OBJECTIVE: To perform a histological and histomorphometric evaluation of bone modeling and remodeling of periodontal alveolar bone under experimental anaemia and polycythaemia. METHODS: Thirty Wistar rats were divided into three groups: control (C), animals were i.p. injected with 0.5 mL of saline solution; anaemia (A), animals were injected with 6 mg/100 b.w. of phenylhydrazine every 48 h; polycythaemia (P), animals were transfused with 2.5 mL/100 b.w. of 80% suspension of homologous erythrocytes. All the animals were sacrificed 14 days after the onset of the experiment. The mandibles were resected, fixed in formalin, radiographed, processed and embedded in paraffin. Bucco-lingually oriented sections were obtained at the level of the mesial root of the first lower molar, and stained with hematoxylin-eosin. Histological and histomorphometric studies were performed on the buccal and lingual plates of periodontal alveolar bone. RESULTS: Histological and histomorphometric studies showed a statistically significant decrease in bone formation both in buccal and lingual plates in group A (anaemia) as compared to group C (control). An increase in active bone formation was found in the lingual plate in group P (polycythaemia) as compared to group C (control). CONCLUSION: The results obtained using this experimental model evidenced alterations in bone modeling and remodeling under conditions of anaemia and polycythaemia and/or associated factors.     

Intracanal reinforcement fiber in pediatric dentistry: a case report.

A technique for the restoration of carious primary maxillary incisors using indirect resin composite crowns and intracanal reinforcement fiber is described. Endodontic treatment was previously performed on each tooth. The advantages of using an intracanal reinforcement fiber include resin composite crown reinforcement, translucency, and relative manipulation facility. In addition, the use of indirect resin composite crowns provides good shape and esthetics, as well as reduced chair time for the child. The technique is illustrated in a case report in which indirect resin composite crowns and an intracanal reinforcement fiber are placed in a 3-year-old girl.     

Treatment of inflammatory salivary gland diseases by using intraductal UV irradiation

A novel technique is offered for treatment of sialadenitis. Ultraviolet irradiation conductors are inserted into the gland via its major duct for subsequent intracorporeal UV therapy of the gland. The results of the treatment are analyzed in 57 cases of sialadenitis observed during 1 to 2.5 years. The technique proved effective enough to be recommended for practical application.     

Radiographic examination of ectopically erupting maxillary canines

This study analyzes the need for and possibility of obtaining further information from different radiographic procedures in 125 children with potential ectopic eruption of the maxillary canines. After clinical examination of 3,000 10 to 15-year-old children, it was found that 7% needed radiographic examinations for determination of the canine position. Eighty-four children (2.8%), with a total of 125 potential ectopically erupting maxillary canines diagnosed clinically and by means of periapical radiographs, were selected and a stepwise extended radiographic diagnostic procedure was used. Most canines in ectopic eruption were positioned palatally; the positions could be assessed with sufficient accuracy from conventional periapical films in 92% of the cases. Only in 37% of the cases, however, could the lateral incisor be projected free from the ectopic canine by the intraoral technique. The lamina dura of the lateral incisor facing the canine was often found to be interrupted. For 29% of the ectopic canines, the lateral incisors could neither be projected free nor judged free from resorptions and a supplementary polytomographic investigation was believed to be necessary. The number of resorbed teeth was doubled by polytomography and altogether 12.5% of the ectopic canines caused resorptions. A stepwise radiographic procedure including polytomography is described and recommended in cases of ectopic eruption of maxillary canines for determining the correct position and ruling out or confirming resorptions on incisors, thereby optimizing the orthodontic treatment planning.     

γ2 phase in conventional dental amalgams — discrete clumps or continuous network? A review

A bstract — Six different types of sources of evidence are examined to study the controversy of whether the γ ₂ phase in conventional dental amalgams occurs in discrete clumps or as a continuous network.
Evidence obtained from corrosion studies, volume-fraction analysis studies and amalgam microstructure studies and evidence associated with the alloy type, the structure of the γ ₂ phase and manipulative techniques are investigated.
Although, under certain conditions, the γ ₂ phase may form a continuous network there is evidence to indicate that, using a conventional Ag₃Sn-based alloy and techniques providing adequate mercury removal, the γ ₂ phase occurs in discrete clumps.