Dentogingival Area Research Articles

Temporal changes of periodontal tissue pathology in a periodontitis animal model.

This study aimed to characterize the early stages of periodontal disease and determine the optimal period for its evaluation in a mouse model. The association between the duration of ligation and its effect on the dentogingival area in mice was evaluated using micro-computed tomography (CT) and histological analysis. Ninety mice were allocated to an untreated control group or a ligation group in which periodontitis was induced by a 6-0 silk ligation around the left second maxillary molar. Mice were sacrificed at 1, 2, 3, 4, 5, 8, 11, and 14 days after ligature placement. Alveolar bone destruction was evaluated using micro-CT. Histological analysis was performed to assess the immune-inflammatory processes in the periodontal tissue. No significant difference in alveolar bone loss was found compared to the control group until day 3 after ligature placement, and a gradual increase in alveolar bone loss was observed from 4 to 8 days following ligature placement. No significant between-group differences were observed after 8 days. The histological analysis demonstrated that the inflammatory response was evident from day 4. Our findings in a mouse model provide experimental evidence that ligature-induced periodontitis models offer a consistent progression of disease with marginal attachment down-growth, inflammatory infiltration, and alveolar bone loss.

Effectiveness of a single-tuft toothbrush for control of newly formed dental biofilm

Aim: To compare the effectiveness of a single-tuft toothbrush (STB) with conventional toothbrushes (CT) to control dental biofilm neoformation in the dentogingival area. Methods: For this cross-sectional prospective blind study, 20 periodontally healthy subjects were selected and randomly divided into 4 groups: STB; CT; CHX - chlorhexidine mouthwash (positive control) and PS - placebo mouthwash (negative control). The subjects were instructed to use only the assigned care method for 72 h with a 7-day washout period between experiments. The evaluated parameters were visible and disclosed plaque indices (PI and DPI), gingival bleeding index (GBI) at baseline (T-0) and at the end of each experimental period (T-72). Results: Data analysis demonstrated that at T-0 no difference was observed for any of the parameters (p>0.05); after 72 h, CT, STB and CHX showed equivalente effectiveness at controlling biofilm. When the PI data were analyzed, between T-0 and T-72, STB was similar to CT and CHX (p<0.05), whereas for DPI, STB was significantly superior to the other methods. Except for PS, all methods yielded similar results for GBI (p<0.05). Conclusions: The tested STB was effective at controlling short-term dental biofilm neoformation on the dentogingival area.

The Role of Inflammatory Cytokines and the RANKL-RANK-OPG Molecular Triad in Periodontal Bone Loss-A Review

Periodontal diseases are chronic inflammatory disorders involving the supporting structures of the teeth. Connective tissue destruction and loss of bone support of the dentition are key features of this disease. Early studies have revealed that biofilm plaque accumulation in the dentogingival area is the primary etiological factor of periodontal diseases. Recent research has not only reinforced the bacterial etiology of periodontal disease, but has also emphasized the role of inflammation in this pathologic process. The host mounts an immune-inflammatory response to combat the bacterial attack. The host response is like a double-edged sword. It eliminates the offending pathogens, but overstimulation and amplification of the same leads to tissue destruction and bone loss. In the mid- 1990s, extensive research in the field of bone biology led to the discovery of the RANKL-RANK-OPG molecular triad. This article explores the mechanisms by which inflammatory host response leads to alveolar bone loss-the role of cytokines, factors that stimulate osteoclastogenesis via the RANKL-RANK-OPG pathway and how inflammation interferes with the uncoupling of bone formation and bone resorption. In addition to the conventional therapeutic modalities aimed at eliminating the microbes, additional therapeutic strategies that interfere with the RANKL-RANKOPG axis may have a protective effect on the bone loss.

Neutrophils-the Sentinels of Periodontal Innate Immunity

The neutrophils play a pivotal role in the innate immune response to periodontal microorganisms. They are rapidly recruited to the dentogingival area where there is accumulation of dental plaque. The antimicrobial armamentarium that they possess not only eliminates the microbes but also partly contributes to the tissue destruction seen in periodontitis. Hence, their action is akin to that of a double-edged sword. Defects in neutrophil numbers or genetic abnormalities in neutrophil migration, chemotaxis and phagocytosis manifest as severe forms of aggressive periodontitis, emphasizing the importance of these cells in innate immunity. Over the past few decades, extensive research in the field of neutrophil cell biology has revealed fascinating facts about this cell. The discovery of neutrophil extracellular traps (NETs) is a novel concept and is considered as the central aspect of innate immunity. In addition to being a key defense cell, the neutrophil not only regulates the immune response but also provides a link between innate and adaptive immune system. The apoptopic neutrophil exerts anti-inflammatory effect. This review focuses on neutrophil functions, microbial killing mechanisms with special focus on neutrophil extracellular traps and the role of neutrophils in the pathogenesis of periodontal disease.

Patterns of Dental Diseases in Diabetic Females in Primary Health Centers in Qatar: Cross-sectional, observational study

Periodontal diseases comprise a large group of predominantly infectious and/or inflammatory disorders affecting periodontal tissues. They are diagnosed by assessment of the dento-gingival area, including the the gingival sulcus depth, and the presence of bleeding with radiographic assessment of the alveolar bone. The prevalence of periodontitis (PD) is reported to be 20-50% worldwide;(1) while the aggressive form of PD is found in less than 10% of the population/2,3). Periodontitis is a chronic infectious/inflammatory disease of multi-factorial etiology(4) with a number of risk factors that are shared with other chronic inflammatory conditions; increasing age, low socio-economic conditions, stress, increased body weight, dyslipidemia, hypertension, metabolic syndrome, cigarette smoking and Diabetes mellitus.(5-6) Systemic reviews have shown a clear association between PD and coronary heart diseases (CHD) emphasizing the need to consider PD as a risk factor for CHD.

Impact of Porphyromonas gingivalis inoculation on ligature-induced alveolar bone loss. A pilot study in rats

Periodontitis is a polymicrobial infection characterized by the loss of connective tissue attachment, periodontal ligament and alveolar bone. The aim of this study was to evaluate the impact of Porphyromonas gingivalis inoculation on the ligature-induced alveolar bone loss (ABL) model in rats. Forty male Wistar rats were randomly assigned to the following groups: G1, control (n = 10); G2, ligature-induced ABL (n = 15); and G3, ligature-induced ABL + P. gingivalis inoculation (n = 15). Rats in G2 and G3 were killed 15, 21 and 30 d after ligature placement, and the following parameters were assessed: microbiological load; ABL; and interleukin (IL)-1β (Il1beta)/Il1ra, Il6/Il10 and Rankl/osteoprotegerin (Opg) mRNA ratios in the gingival tissues, as determined by quantitative PCR. Microbiological analyses demonstrated that rats in G1, G2 and G3 were positive for the presence of bacteria (determined using PCR amplification of the 16S gene), but that only the treatment sites of rats in G3 were positive for P. gingivalis at all time-points investigated. Histometrically, significant bone loss (p<0.001) was observed for both ligated groups (G2 and G3) compared with the nonligated group (G1), with higher ABL observed for G2 at all the experimental time-points. Furthermore, gene-expression analysis demonstrated that the presence of P. gingivalis in the dentogingival area significantly decreased the Il1β/Il1ra, Il6/Il10 and Rankl/Opg mRNA ratios compared with ligature alone. Within the limits of this pilot study, it was concluded that inoculation of P. gingivalis affected the ligature-induced ABL model by the induction of an anti-inflammatory and antiresorptive host response.

Periodontal infection control: current clinical concepts

The main objective of the treatment of patients with periodontitis is to establish adequate infection control in the dentogingival area. Pocket/root instrumentation (scaling and root planing), combined with effective self‐performed supragingival plaque control measures, constitute the basic treatment modalities, but also locally applied antiseptics and antibiotics may be utilized. The purpose of this article is to give an overview of current clinical concepts on periodontal infection control.

Extensive expression of TGF-beta1 in chronically-inflamed periodontal tissue.

The host immune response in chronic marginal periodontitis (CMP) raised against bacteria colonizing the dentogingival area is modulated by cytokines. This study examines the distribution of the transforming growth factor-beta1 containing (TGF-beta1+) cells in formalin-fixed and paraffin-embedded gingival specimens from 11 patients with chronic marginal periodontitis and 7 persons with healthy gingiva. Inflamed periodontal tissue contained a 100-fold more TGF-beta1+ cells than healthy gingiva. Diverse morphological TGF-beta1+ cell types were discerned. Double immuno-enzymatic and -fluorescence staining revealed that TGF-beta1+ cells comprised 21-29% macrophages 2-3% T-cells, 3-9% B-cells, 34-35% neutrophilic granulocytes and 7-10% mast cells. The densities of all TGF-beta1+ cell types in CMP were strongly increased in the connective tissue adjacent to the pocket epithelium, in the lamina propria and adjacent to the oral epithelium. In lesions with extensive inflammation, expression was also marked in pocket epithelium. TGF-beta1 is an immunosuppressive cytokine that stimulates wound healing. Upregulation of the cytokine in inflamed gingiva may counterbalance for destructive gingival inflammatory responses that are simultaneously taking place in patients with CMP.

Chapter 2: Functional aspects of the IgA system at the dentogingival area

Chapter 2: Functional aspects of the IgA system at the dentogingival area

Scanning electron microscopic investigation of changes in the dentogingival area during experimental gingivitis

The purpose of this study was to investigate the changes that occur in the dentogingival area during experimental gingivitis using a replication technique and scanning electron microscopy (SEM). The upper 1st premolars of 20 subjects were examined prior to plaque accumulation, after plaque had become clinically visible and after 3 weeks plaque accumulation. 3 distinct zones were examined: the tooth surface and its integuments, the gingival crevice and the oral gingiva. Surface features such as perichymata, pits, depressions and cracks were rapidly covered by plaque deposits. These had a raised globular surface with occasional embedded desquamated epithelial cells. Raised plaque colonies were frequently seen by the end of the study. Initially, the gingival crevice presented a layered undulating appearance. With plaque accumulation many desquamating epithelial cells were seen and variations occurred in the width of the crevice. These changes were mirrored in the oral gingiva. The junctional epithelium was initially smooth with occasional pores and emigrating leucocytes. As plaque accumulated, the presence of pores and leucocytes increased and considerable disruption by desquamating epithelial cells was noted. No subject proved resistant to the influence of plaque-induced changes.

Les Bacteroides de la cavite buccale. Pathogénicité et facteurs de virulence

Les Bacteroides de la cavite buccale. Pathogénicité et facteurs de virulence

Histologic reactions in gingival and alveolar tissues during tooth movement in rabbits.

In this (semi)quantitative animal study the reaction of the gingival tissues to experimental tooth movement is described and compared to the reaction in the periodontal ligament. To this end, rabbit first incisors were moved sideways with helical torsion springs for periods varying from 3–72 hours. The initial force of the springs was 50 gf. Comparison with control animals and animals wearing passive springs showed that tooth movement itself leads to trauma in the dentogingival area within only a few hours. This trauma is characterized by tears and ulcerations in the epithelium, by tears and ruptures in the fibres, by leukocytic infiltration and by the presence of extravascular erythrocytes. Between the incisors, however, a firm connective tissue septum, acting as a reinforcement to the dentogingival area, remains intact. Tissue damage significantly increases with time. After 72 hours of orthodontic force, however, the interdental papilla seems to have recovered to some extent. The histologic data of the dentogingival area in animals wearing active springs, were compared to those of the underlying periodontal ligament by multivariate analysis of variance. This analysis showed, that there are significant differences between the tissue reaction in the labial and palatal segments, and between the dentogingival and dentoalveolar areas. Furthermore, a close relationship was found between the damage to the fibres and the occurrence of extravascular erythrocytes and leukocytes. It was therefore concluded, that local tissue damage, characterized by rupture of fibres, leads to an inflammatory reaction in the gingiva and the periodontal ligament.