Local Contributory Factors

Question 1

Biofilm

Answer 1

Microbial community enveloped by extracellular biopolymer which the microbial cells produce

Question 2

Animal studies

Answer 2

Experimental periodontitis in beagle dogs (Lindhe,Hamp and Loe 1973)

Plaque accumulation causes development of periodontal disease (subclinical gingivitis –> gingivitis –> periodontitis)

Question 3

Epidemiological studies

Answer 3

Do not show cause and effect, but shows if a factor is associated with periodontal disease

Sri Lankan and Norwegian studies showed poorer oral hygiene is associated with poorer periodontal health, and periodontal disease in older individuals is more severe than those in younger age groups

Question 4

Experimental evidence

Answer 4

Experimental gingivitis in man (Loe, Theilade and Jensen 1965)

Subjects with good OH and 0 gingivitis score at baseline abstained from OH for 2-3 weeks

Subjects were examined using gingival index, plaque index and microbiological findings

Withdrawal of OH resulted in gross accumulation of plaque and development of gingival inflammation

Time taken to develop gingivitis varies from 10-21 days

Reinstitution of effective OH resulted in resolution of gingivitis

Question 5

Experimental studies advantages and limitations

Answer 5

Possible to show cause and effect if well controlled, but usually short term study with ethical concerns

Question 6

Clinical evidence

Answer 6

Effect of preventative programme on plaque, gingivitis and caries in school children (Axelsson and Lindhe 1974)

Effect of controlled OH procedures on caries and periodontal disease in adults (Axelsson and Lindhe 1978)

Effective OH supplemented by professional therapy could control dental caries and prevent periodontal disease

Question 7

Microbiological evidence

Answer 7

Applicable to real world, but must be well controlled and high drop outs may invalidate the study

Question 8

Plaque retention factors

Answer 8

Calculus

Anatomical factors (multiple roots, furcations, concavities on roots, deep fissures/grooves, enamel projections/pearls)

Maligned teeth (crowding, impaction)

Restorations (deficient margins, overcontours, overhangs, biologic width violations)

Appliances (RP, FP, ortho)

Factors related to periodontal disease

Question 9

Pathogenic potential of biofilm

Answer 9

Ability to colonise
Ability to evade host responses via capsule
Ability to cause direct tissue damage via collagenase
Downregulate inflammatory response by signalling