Preventive therapy for periodontal diseases

Evaluation of mid-buccal gingival recessions and occlusal interferences

BACKGROUND

Dental malocclusions may cause disruption in occlusal harmony, and destructive interferences during mandibular functional movements can be seen. Ideal occlusal contacts during dynamic mandibular movements may be crucial for preventing the occurrence of mid-buccal gingival recession (mbGR). While determining mbGR risk factors in young adults, the effect of occlusal interferences on mbGR has not yet been focused on. Based on this gap, this field needs to be clarified with new studies.

OBJECTIVE

The aim of this case-control study was to evaluate the relationships between the presence, extent and severity of mbGRs to dental malocclusions, occlusal interferences in anterior (AG) and lateral guidance (LG) and to determine the potential risk indicators in a young population.

METHODS

A total of 149 dental students were comprised and 70 of them presented mbGR(s) and 79 did not (18-25 years, 4553 teeth). Periodontal status was assessed with full mouth bleeding (FMBS) and plaque score (FMPS), probing depth, clinical attachment level, recession depth and keratinised tissue width (KTW) by a periodontist. Malocclusions and occlusal interferences were evaluated by an orthodontist. Logistic regression analyses provided data on the effect of occlusal interferences and the other indicators towards mbGR.

RESULTS

The mean of the number of teeth with mbGR(s) per subject was 4.3. The mean of the overall extent of teeth with mbGR(s) was 14.2%. FMBS, decreased KTW, self-reported bruxism, group function occlusion, increased contact number of all teeth and only premolars/molars in AG or LG and Class III malocclusions were significantly associated with the presence of mbGR. Decreased KTW presenting mbGR in the mandible and non-carious cervical lesion adjunct to mbGR significantly increased the odds of the severity of mbGR. Group function occlusion revealed higher mbGRs in premolar/molars than canine guided occlusion.

CONCLUSION

Increase in the occlusal interferences in premolars/molars during lateral and anterior guidance may have an effect on the presence and severity of mbGR. Further studies should be designed to confirm these findings.

Vaccines and photodynamic therapies for oral microbial-related diseases

The mouth is a favorable habitat for a great variety of bacteria. Microbial composition of dental plaque is the usual cause of various oral diseases in humans, including dental caries, periodontal disease and halitosis. In general, oral antibacterial agents such as antibiotics are commonly used to treat oral bacterial infection. Traditional periodontal surgery is painful and time-consuming. In addition, bacterial resistance and toxicity of antibiotics have become a global pandemic and unavoidable. Recently, vaccines for dental caries and periodontal disease have been developed and applied. Moreover, the use of photodynamic therapy has become an alternative to antibiotic drugs. The purpose of this article is to highlight the advantages of vaccine therapy and photodynamic therapy for oral microbial-related diseases compared to treatments with antimicrobial agents and traditional periodontal surgery.

High-titer recombinant adeno-associated virus production utilizing a recombinant herpes simplex virus type I vector expressing AAV-2 Rep and Cap

Recombinant adeno-associated virus type 2 (rAAV) vectors have recently been used to achieve long-term, high level transduction in vivo. Further development of rAAV vectors for clinical use requires significant technological improvements in large-scale vector production. In order to facilitate the production of rAAV vectors, a recombinant herpes simplex virus type I vector (rHSV-1) which does not produce ICP27, has been engineered to express the AAV-2 rep and cap genes. The optimal dose of this vector, d27.1-rc, for AAV production has been determined and results in a yield of 380 expression units (EU) of AAV-GFP produced from 293 cells following transfection with AAV-GFP plasmid DNA. In addition, d27.1-rc was also efficient at producing rAAV from cell lines that have an integrated AAV-GFP provirus. Up to 480 EU/cell of AAV-GFP could be produced from the cell line GFP-92, a proviral, 293 derived cell line. Effective amplification of rAAV vectors introduced into 293 cells by infection was also demonstrated. Passage of rAAV with d27. 1-rc results in up to 200-fold amplification of AAV-GFP with each passage after coinfection of the vectors. Efficient, large-scale production (>109 cells) of AAV-GFP from a proviral cell line was also achieved and these stocks were free of replication-competent AAV. The described rHSV-1 vector provides a novel, simple and flexible way to introduce the AAV-2 rep and cap genes and helper virus functions required to produce high-titer rAAV preparations from any rAAV proviral construct. The efficiency and potential for scalable delivery of d27.1-rc to producer cell cultures should facilitate the production of sufficient quantities of rAAV vectors for clinical application.

Prevention of periodontal disease

Periodontal disease is the most common disease affecting adult dogs and cats. It is also a very preventable disease. The insidious nature of the disease and requirement for the pet owner to be actively involved make client and public education absolutely vital. Although clients are commonly aware of their pets' bad breath, they rarely notice gingivitis, fractured teeth, and traumatic malocclusions. The annual National Pet Dental Health Month program has resulted in a tremendous increase in public awareness. Veterinarians must carry this further in their everyday practices, convincing our clients of the need for preventive dental care. It is only through clients' ongoing desire and persistence that a long-term preventive program can be successful. This requires a coordinated effort by the entire hospital staff. When successful, clients' pets will live healthier and longer lives.

Pathogenic mechanisms in periodontal disease

Periodontal diseases have been considered as "infections" in which micro-organisms initiate and maintain the destructive inflammatory response. Host-mediated tissue destruction occurs via complement activation and the release of lysosomal enzymes, and connective tissue matrix metalloproteinases. Microbial enzymes may damage connective tissues directly, and, together with toxic metabolites and structural materials, are thought to disrupt the reparative activities of fibroblasts and cells of the immune defenses. The significance and relative contributions of host and microbial factors to the disease process remain unresolved. Environmental changes in the gingival sulcus and periodontal pocket and tissues, the degree of the host response and nutrient availability, concomitant with disease progression, compromise tissue metabolism and repair, and allow for enhanced or de novo expression of microbial virulence factors, such as proteases, which alter microbial pathogenicity. Proteolytic destruction of specific antibodies and complement by both viable and non-viable bacterial cells may retard phagocytic killing and removal of pathogens, thus prolonging the inflammatory response. Bacterial products may indirectly mediate tissue destruction by stimulating release of matrix metalloproteinases or by proteolytically inactivating the specific inhibitors of these enzymes.

Microbial ecology of dental plaque and its significance in health and disease

Dental plaque forms naturally on teeth and is of benefit to the host by helping to prevent colonization by exogenous species. The bacterial composition of plaque remains relatively stable despite regular exposure to minor environmental perturbations. This stability (microbial homeostasis) is due in part to a dynamic balance of both synergistic and antagonistic microbial interactions. However, homeostasis can break down, leading to shifts in the balance of the microflora, thereby predisposing sites to disease. For example, the frequent exposure of plaque to low pH leads to inhibition of acid-sensitive species and the selection of organisms with an aciduric physiology, such as mutans streptococci and lactobacilli. Similarly, plaque accumulation around the gingival margin leads to an inflammatory host response and an increased flow of gingival crevicular fluid. The subgingival microflora shifts from being mainly Gram-positive to being comprised of increased levels of obligately anaerobic, asaccharolytic Gram-negative organisms. It is proposed that disease can be prevented or treated not only by targeting the putative pathogens but also by interfering with the processes that drive the breakdown in homeostasis. Thus, the rate of acid production following sugar intake could be reduced by fluoride, alternative sweeteners, and low concentrations of antimicrobial agents, while oxygenating or redox agents could raise the Eh of periodontal pockets and prevent the growth and metabolism of obligately anaerobic species. These views have been incorporated into a modified hypothesis (the "ecological plaque hypothesis") to explain the relationship between the plaque microflora and the host in health and disease, and to identify new strategies for disease prevention.