To advance and promote the discipline and professional practice of epidemiology in Ontario public health units
Please click here to visit our new website




6C deft/DMFT Index

Description | Specific Indicators | Corresponding Mandatory Objectives | Corresponding National Indicators | Data Sources |  Alternative Data Sources | ICD Codes | Analysis Check List | Method of Calculation |  Basic Categories | Indicator Comments | Cross-References to Other Sections | References  


  • The proportion of the number of teeth decayed, missing/extracted or filled because of decay to the total number of teeth examined among children at school entry (kindergarten).



Deft, DMFT, Dental, teeth, child, decay, cavities, caries, DIS, oral health, Mandatory


Specific Indicators

  • Deft/DMFT index

  • Decayed

  • Missing/extracted

  • Filled

Corresponding Mandatory Objectives

  • To reduce the prevalence of dental diseases in children and youth.


Corresponding National Indicators



Data Sources (see Resources: Data Sources)

Numerator & Denominator: Ontario Dental Indices Survey

Original source:
Ontario Dental Indices Survey, [Public Health Unit]

Distributed by:
Public Health Unit

Suggested citation (see
Data Citation Notes): Dental Indices Survey [years], [Public Health Unit], Extracted: [date]


Survey Questions



Analysis Check List

  • Determine what sampling methodology was used within a health unit before making comparisons of the DIS over time or with other health units.

  • The WHO Modified Index used in the DIS ensures a code for each tooth1:
    n 00 = Sound
    n 01 = Sound with sealant
    n 02 = Decayed pit and fissure
    n 03 = Decayed smooth surface
    n 04 = Decayed both pit and fissure and smooth surface
    n 05 = Filled, with no other decay in filling or crown
    n 06 = Filled and decayed (this code is counted as "d" or "D" in all reports)
    n 07 = Missing due to caries
    n 08 = Absent or a primary tooth with a permanent successor present (congenitally/unerupted/exfoliated primary tooth/trauma). See notes in the Dental Indices Software Program Manual for more specific coding.
    n 09 = Sound abutment tooth or crowned due to trauma (a crown placed for reasons other than caries)
    n 10 = To be lost/extracted due to caries (i.e., more than two-thirds of the crown has been lost or abscessed but no visible sign of decay)
    n 99 = Missing value


Method of Calculation 


number of decayed, missing/extracted or filled teeth in school entry

(kindergarten) children

* 100

total number of teeth examined in kindergarten children


Basic Categories

  • Geographic areas: public health unit.


Indicator Comments

  • The deft/DMFT Index is a general indicator of dental health status of the population (particularly among children), and is considered reliable.

  • DMFT refers to permanent teeth: D = Decayed, M = Missing due to caries (not from trauma, orthodontic extraction, congenitally missing, etc.), F = Filled, T = Teeth.

  • deft refers to primary (baby) teeth: d = decayed, e = extracted due to caries, f = filled, t = teeth. Teeth missing for caries are not recorded because of the exfoliation process and not knowing whether such teeth were carious before they fell out.

  • The lower the index, the better the dental health of the population. The DMFT score for any individual can range from 0 to 32, in whole numbers. A mean DMFT score for a population can have fractional values.2 

  • A def/DMF index can also be applied to tooth surfaces (designated as defs/DMFS). 

  • A deft/DMFT Index of zero does not mean that the child is "caries-resistant" – they are merely caries-free at the time of survey. The child may have early stage caries not visible to the naked eye (surveys do not generally use radiographs) or may have had decay (d) and/or restorations (f) in their primary teeth which have now exfoliated.2

  • The Index gives equal weight to missing, untreated decayed and well-restored teeth. The Index may overestimate the degree of oral problems since filled teeth might have otherwise been scored as sound teeth since the cavity may not have been apparent.2 Analysis of each of the deft/DMFT components (i.e., decayed, missing, filled separately) is useful for understanding dental health trends.

  • The deft/DMFT Index does not consider sealed teeth.2 As part of the WHO Modified Index that is used in the DIS (see Indicator Check-list above), public health units record the number of teeth with sealants to determine the number of children with fissure sealants.

  • The deft/DMFT index records past history and is cumulative.

  • Although public health units are required by Mandatory Health Programs and Services Guidelines to conduct the DIS for all school entrants, many do not have sufficient resources and instead sample only some of the children. Each public health unit uses a different methodology depending upon local resources. As a result, the DIS is not comparable across health units. Comparisons within a health unit over time may be appropriate as long as the sampling methodology has remained consistent.

  • Because the DIS is conducted for children at school entry (Junior Kindergarten and Senior Kindergarten) throughout the school year from September to June, children can range in age from 3 to 6 years.

  • The Mandatory Health Programs and Services Guidelines have the objective “to reduce the prevalence of dental diseases in children and youth”. This indicator is one measure of this objective, along with other dental indicators. However, information about youth is not available. Generally, information is available only for children on school entry in most health units.

  • Oral disorders can have a significant impact on general health and well-being:
    n Dental decay is caused by bacterial infection. It is one of the most common disorders of childhood. It can cause pain, poor sleep and poor eating habits in children. Dental decay can be a contributing factor in “failure to thrive” whereby children have low weight and height for their age.3
    n Periodontal disease, a chronic infection caused by bacteria that accumulate in plaque, has been linked to various diverse health problems including pre-term low birth weight babies, heart disease, stroke, pneumonia, and chronic respiratory disease.3
    n Poor oral health can lead to poor nutrition and decreased quality of life due to pain, and chewing and speech problems.3

  • There is a strong link between oral health and income. Low-income children and new immigrants are most likely to have poor oral health.3

  • deft/DMFT Index results for Ontario for age 5 years4:

    1972 – 2.47
    1974 – 2.32
    1976 – 2.30
    1978 – 1.96
    1980 – 2.06
    1982 – 1.81
    1984 – 1.48
    1986 – 1.20
    1988 – 1.10
    1990 – 1.16
    1993 – 1.24

Cross-References to Other Sections



  1. Ontario Ministry of Health. Dental Indices Software Program Manual. December 9, 1997.

  2. Burt BA, Elund SA. Dentistry, Dental Practice and the Community. Philadelphia: W.B. Saunders Company, 1999.

  3. Locker D, Matear D. Oral disorders systemic health, well-being and the quality of life: A summary of recent research evidence. 

  4. Bennett S. Results from the 1993-94 Ontario Dental Health Indices Survey. PHERO 1996:355-358.


Date of Last Revision: November 10, 2004.

Treasurer/Secretary | Admin | Members Login