In Dental Caries there are many theories about the initiation and progression of dental caries but the Window of infectivity factor has been studied only by some scientists who have studied both primary and permanent Dentition with birth to 5 years in decidious and eruption to 5 years in permanent teeth.
What is Window of Infectivity in Dental Caries:
It is the time period in which the initial acquisition of Streptococcus Mutans takes place on either a permanent tooth or a primary tooth. Both the Primary and Permanent teeth erupt into the oral cavity and thus provide a completely virgin ground of dental tissue for the micro organisms to attack on, this enables the Streptococcus Mutans to colonize in the oral cavity before other bacteria colonize to prevent competition.
- Window of Infectivity for Decidious or Primary Teeth: 7-31 months
- Window of Infectivity for Permanent Teeth: 2-6 years
The Window of Infectivity in Primary Dentition was monitored and studied by Caufield (1993) who monitored the oral cavity levels form birth to 5 years where he noted the initial acquisition of Streptococcus mutans and identified the period as “Window of Infectivity”.
Krass et al (1967), Edrman et al (1975) were the first to identify the Second Window of Infectivity as 6-12 years in Permanent Teeth as they erupt at that period of time.
The Window of Infectivity theory is completely based on Streptococcus Mutans attack on Teeth and no other micro organisms are considered in this theory and according to Davey and Rogers (1984) children acquire additional strains of MS as they get older and new teeth emerge but these strains remain undetected as they are in very low numbers.
This Window of infectivity is important because this tells us the period in which the bacteria which initiates Caries formation is getting attached to the teeth so we can inform and educate parents about the importance of this time period and the precautions they should follow to prevent caries by removing S. Mutans in this time period.
As we know that Streptococcus Mutans which initiates Caries takes about 5-6 years to penetrate the enamel approximately of 2.7 mm thickness in normal human tooth.
hey doc good job.. am a dentist too. doing my intership at chennai. can u pls do a detailed post on cast metals in endodontics? will be really helpfullll…..
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Hello doc,why is the first moler prone to dental carries…
friends,
The exact reason for the first molar being more prone to caries attack is not known. However, some predisposing factors which lead to that tooth being prone to caries attack is known. It erupts at 6 years of age when all the other teeth are primary ones and most parents are not aware of the new permanent tooth erupting into the oral cavity, hence neglected. First permanent molar being the posterior most tooth in the arch for a long time, the child tends to neglect that tooth while brushing. Some even have gagging sensation while brushing and avoid that tooth while brushing. More over, by 6-7 years of age most children are left alone to brush their teeth without supervision, that tooth gets affected early. The choice of food preferences are being established during the early school years, when the child shows an inclination towards sweet and sticky toffee and chocolates, and has access to these in schools. Lastly if the child has nursing caries and a high deft index, these newly erupted first permanent molars and suseptible to caries attack.