## 4 Discussion
Unsteady movements of the handpiece must be avoided at all times due to the inaccuracy of the result obtained. [PERSON] et al. (1996) [7] identified another problem that had not been mentioned in any study before. The second Periotest recording, which was taken to evaluate the reproducibility of the results, was considerably lower than the first. The only reasonable explanation given by the authors for this discrepancy is that not enough time was allowed for the periodontium to recover to its previous functioning state between the two attempts. These findings seem to be supported by [PERSON] et al. (2003a and 2003b) [5,6] who quantified the time intervals at no less than 15 min. It should be noted that the _Periotest_ as a diagnostic tool is probably impractical to use in daily routine dental treatment or to identify the presence of tooth mobility in cases of periodontitis if the practitioner is not experienced in the use of the device, as well as fully aware of its limitations. An incorrect reading requires a resting period of up to 15 min, according to [PERSON] [7], before a new reading is attempted, which makes it time-consuming. Although his findings are scientifically correct, it is impractical to follow his suggestions in practice or even research. If we were to abide by the suggestion that following an erroneous reading with the _Periotest_, a 15 min interval is necessary before a second _Periotest_ reading is taken, then a simple tooth mobility evaluation using this device in practice could take more than an hour to complete. This is time-consuming and very often not acceptable by either the patient or the dental practitioner. Neither one can allow that much time to examine the potential presence of tooth mobility on only one tooth, especially if the same assessment needs to be performed on all the patient's teeth. In each recording session, the results of the reproducibility study show that subsequent readings to the first (the second and third readings of each recording session) were poorer; however, the standard deviation from the mean value of each recording session is no higher than \(\pm\)2 PTV units, which is, as stated earlier, an acceptable and statistically nonsignificant error. Taking into consideration the results from our study, it was concluded that the possible error or deviation in accuracy in tooth mobility results from the _Periotest_ device, if we were to take readings in less than 15 min intervals, was acceptable and more practical to work with for both the researcher and the subjects/patients. The Periotest value will correlate significantly with pocket depth, bone destruction, attachment loss and plaque index, as well as tooth mobility. It integrates the influences of the periodontal tissue changes of which 70% originate from bone changes and 30% from soft tissue changes. This does not apply to gingivitis because there is no change in the periodontal structure. Finally, restorations such as fillings, crowns or even crowded teeth have no or an insignificant bearing on the measurements. Splinted teeth or fixed-fixed bridges will produce the value of the entire block. Further examination of the _Periotest_ readings for this study supports the same conclusions reached by [PERSON] et al. (1992) [4] and [PERSON] (1997) [28]; positive (higher) or negative (lower) _Periotest_ values correspond to bone loss and alveolar bone height, respectively. Younger patient groups have significantly lower or negative values for all groups of teeth because they have less bone loss surrounding the tapped teeth. This becomes even more evident for the canine and molar teeth than the central incisors because the canines have a thick long root, while the molars are multirooted teeth with better bone support. On the other hand, anterior incisors have slimmer and often short roots, with very thin alveolar bone. Age and oral hygiene are well-known factors negatively affecting the bone support of teeth over the years. Unsatisfactory restorations and missing teeth could also play a part in it.