Brushing instructions play a crucial role in achieving good plaque control [14]. The oral cavity should be stained with a plaque-staining solution to visualize the areas with plaque deposition, and demonstrations should be given using a jaw model to ensure that patients follow proper brushing instructions. The evaluation methods used in clinical practice for assessing plaque control should possess the following characteristics: highly objective evaluation; quantification; simple and accurate examination and recording; high reproducibility; and easy understanding of the evaluation by the operator and patient.
PCR, which was published by O'Leary et al. in 1972, is a method in which the surgeon evaluates the stained area of dental plaque in the oral cavity by direct observation or using a dental mirror. As an oral hygiene evaluation method, it is widely used in clinical practice and research to compare the effects of treatment [8]. However, this method has been concerned that the PCR method shows differences in the measurement values owing to differences in evaluation criteria among surgeons, even in the same patient with each visit. Moreover, it is not possible to record plaque adhesion findings at the time of evaluation.
The solution to these problems is the acquisition of a simple digital image of the dentition.
Recording the oral cavity with an optical camera can indirectly aid in the evaluation of the oral hygiene status; however, considering the time required for filming, the need for assistants, and the burden on the patient, this method is burdensome for both the surgeon and patient at every maintenance visit.
An IOS can record intraoral conditions as digital images, and measurements can be performed by a single operator. Moreover, the burden on the patient is low. Intraoral assessment using IOS has been reported in recent years[12, 13]༎IOS, which can be color-coded, is used to assess the plaque adhesion status.
Giese-Kraft et al. compared images recorded using an intraoral camera and IOS after plaque staining on a monitor and reported that the results were very similar [12].
Jung et al. reported that the entire tooth surface could not be observed in the central image owing to the convexity of the tooth surface in the image acquired by the intraoral camera; however, the entire tooth surface could be visualized on the IOS image [13]. Therefore, the amount of plaque visualized on the IOS image was slightly greater than that visualized on the intraoral camera image.
In our previous study that examined the utility of IOS for PCR measurements, the IOS image obtained using IOS clearly revealed the presence of stained dental plaque [11]. Rotating the image aided in visualizing the stained plaque, especially in areas that were difficult to observe directly, such as the lingual and most centrifugal posterior molar areas.
The results showed that the PCR values obtained using IOS were higher than those obtained using direct evaluation. The IOS evaluation of the posterior teeth yielded higher values than those obtained using direct evaluation. Areas with significant differences were difficult to view directly and had to be visualized using a dental mirror. Therefore, the field of view to be evaluated was considered to have become narrower, and the state of plaque adhesion could not be detected. The IOS image enabled magnification and rotation, which facilitated measurement even in areas that were difficult to view directly.
This aspect is corroborated by a subsequent study that reported that intraoral digital monitors are considered more useful than dental mirrors for assessing stained plaque and tartar in areas that are difficult to visualize directly [15]. And Meseli S et al reported that Intraoral digital scanning offers a distinct advantage in diagnosing dental plaque due to its 3-dimensional imaging capabilities [16].
In contrast, no difference was observed in the PCR measurements of the anterior teeth obtained using IOS and direct viewing. This may be attributed to the fact that these areas could be viewed directly, and there were no problems with obtaining PCR measurements.
These results suggest that the IOS is useful for assessing the oral hygiene status. IOS can aid in accurately evaluating the status of dental plaque adhesion by visualizing it on the monitor, especially in the observation of areas that cannot be viewed directly and require dental mirrors. In addition, images can be acquired easily, enabling transitional evaluation and evaluation by multiple evaluators, which is more effective than conventional techniques.
However, oral hygiene assessment using IOS has some limitations. Some teeth could not be scanned using the IOS in the present study. This was especially true for most posterior molars. The large tip size of the current IOS may make it difficult to place it in the imaging position when the mouth opening is limited. The placement is also affected by the height of the masticatory muscles and the crest of the jaw. Therefore, it is necessary to develop a smaller tip for recording the entire dentition.