The estimation of the needs for periodontal treatment in adult Hong Kong Chinese using the community periodontal index of treatment needs (CPITN) and an evaluation of a minimal periodontal treatment programme

The Community Periodontal Index of Treatment Needs (CPITN) was designed primarily to assess periodontal treatment needs in populations but has been applied to individuals with some modifications (Ainamo et al., 1982; Cutress et al., 1987). Although the CPITN is widely used, many of the assumptions upon which the index is based have been questioned in view of an improved understanding of the periodontal disease process and of responses to different treatment approaches. The purpose of this investigation was to; (1) assess the time required to provide periodontal treatment in a group of adult Hong Kong Chinese; (2) examine if a relationship exists between CPITN scores and treatment times; and (3) evaluate the effects of oral hygiene instruction in the absence of scaling. Based upon CPITN treatment need indications, a sub-sample of the 668 subjects aged 35-44 years examined during the 1984 Hong Kong Survey of Adult Oral Health (Lind et al., 1986) was defined comprising all 104 Treatment Need (TN) "3" subjects and 100 randomly selected (TN) "2" subjects. 43 subjects (21%) of this sample eventually participated in this study, the clinical part of which was conducted between 1987 and 1989. During the first six months of the study, a split-mouth approach was used to assess the outcome of oral hygiene alone as against oral hygiene and scaling. Thereafter, routine periodontal treatment was undertaken and monitored for a total period of 15 months. Treatment times were assessed using the methods of time study and activity sampling while clinical outcomes were assessed on probing depth, calculus, and bleeding on probing. The mean initial oral hygiene time for this sample was 39 minutes, while for the 6- and 12-month maintenance appointments, this reduced to a mean of 15 and 11 minutes respectively. The mean initial scaling time for sextants was 23 minutes, however for those sextants where scaling had been deferred until six-months after the provision of oral hygiene instruction, the mean scaling time was reduced by one-half. Significantly less time was required for scaling at subsequent maintenance appointments. Rather few sextants eventually received complex periodontal treatment thereby making meaningful comparisons difficult. The highest subject CPITN score was not useful as an indicator of oral hygiene instruction time during any phase of the study, while the highest sextants CPITN score was only useful as an indicator of treatment time for initial scaling. Activity sampling revealed that 61% of hygienist time was unproductive (patient late, cancelled, failed or not booked), and that only 29% of total time was devoted to primary activities (examination, instrumentation and other preventive activities). Over two-thirds of primary activity time was spent on scaling. Statistically significant reductions in CPITN scores, probing depths and bleeding after probing were observed over the first six months of treatment both in sextants which received conventional periodontal treatment and those which received only oral hygiene, however the reductions were less in the latter. The hierarchical design of the CPITN did however obscure the detection of some of the improvements in non-instrumented sextants since calculus (CPITN code 2) was not removed. Scaling provided at the six- month recall in sextants which had previously only received oral hygiene, resulted in further improvements in all clinical parameters. In summary, the principal findings of this study are that: For adult Hong Kong Chinese treated under the conditions of this study, the mean initial oral hygiene time was somewhat less than the time estimates provided in TRS 621 (WHO, 1978); The mean time for initial scaling of sextants at baseline was within the range suggested by TRS 621; For subsequent maintenance phases, the mean oral hygiene time per subject and the mean scaling time per sextant were greater than the TRS 621 estimates; Deferment of initial scaling for a period of six-months after oral hygiene instruction reduced scaling time by one-half thereby providing a basis for the development of more time efficient methods for the provision of periodontal treatment; The CPITN score was not useful as an indicator of the time required for individual components of treatment except for initial scaling time at baseline; Activity sampling revealed that over half of hygienist time was unproductive; Improvements in periodontal health can take place following oral hygiene instruction in the absence of scaling; Scaling enhances the improvements in periodontal health achieved by oral hygiene alone; The CPITN has deficiencies due to its hierarchical nature when used for the monitoring periodontal treatment outcomes; The CPITN as modified by Takahashi et al., (1988) confers no advantage in monitoring the outcomes of a minimal periodontal treatment programme involving oral hygiene in the absence of scaling