Influence of different narrative instructions to record the occlusal contact with silicone registration materials

Accuracy of optical interocclusal registration using an intraoral scanner

PURPOSE

This study aimed to clarify the effect of occlusal force on appropriate optical interocclusal registration in clinical practice, considering periodontal ligament and jawbone deformation.

METHODS

Forty participants with natural, healthy dentition were enrolled (19 men and 21 women; mean age, 27.7 ± 2.0 years). A TRIOS3 intraoral scanner was used to scan the right lateral first premolar to the second molar areas of the upper and lower jaws. During scanning for interocclusal registration, participants were instructed to "bite normally," "bite lightly," and "bite strongly" to obtain data for the three occlusal patterns. The standard triangulated language (STL) data for each occlusion condition were superimposed using the appropriate software, following which the tooth displacement was calculated. The conventional method was also used to record the occlusal contact area for a silicone model using a dental contact analyzer.

RESULTS

Tooth displacement was significantly lower for the strong-bite condition than for the weak-bite condition (0.018 mm vs. 0.028 mm, P<0.05). As the occlusal force increased, the occlusal contact area also increased, and significant differences were observed among the different occlusal conditions (P<0.05).

CONCLUSIONS

Occlusal contact area changed depending on the bite force when using the silicone impression or optical intraoral scanning methods. Moreover, using optical impression methods in "strong bite force" may reduce the deviation and allow for stable interocclusal registration.

Time of day-dependent deviations in dynamic and static occlusion: A prospective clinical study

STATEMENT OF PROBLEM

The registration of dental occlusion is essential for prosthodontic treatment. However, studies on time-dependent changes of static and dynamic occlusion that may affect definitive restorations are lacking.

PURPOSE

The purpose of this prospective clinical study was to use conventional and digital occlusal registration techniques to evaluate time-dependent fluctuations in static and dynamic occlusion.

MATERIAL AND METHODS

The static and dynamic occlusion of 19 healthy individuals (14 women and 5 men with a mean ±standard deviation age of 30.8 ±4.8 years) was examined 3 times a day using occlusal foil (12-μm occlusion foil) and a digital sensor (T-Scan III). The procedure was repeated after 14 days. The statistical analysis covered all registrations referencing the first measurement point to assess occurring differences, and changes per tooth and arch were determined (α=.05). Potential influencing factors were calculated by using mixed logistic regression. Marginal probabilities were calculated considering the registration technique and the time of measurement.

RESULTS

Significant differences were found between registered occlusal patterns and the different registration techniques. Occlusal changes per maxillary dental arch were observed with static foil registration (P<.001; 98.8%), left laterotrusion foil registration (P=.001; 29.6%), right laterotrusion foil registration (P=.001; 29.6%), static sensor registration (P<.001; 20.3%), left laterotrusion sensor registration (P=.001; 71.7%), and right laterotrusion sensor registration (P=.005; 67.7%). None of the techniques showed higher probabilities of occlusal changes at a given time of day with respect to time-dependent changes.

CONCLUSIONS

The study revealed that occlusion cannot be considered constant and that the topography and intensity of the contact points vary. Circadian occlusion variance can be assumed without preferring a specific time of the day. This differentiated view of occlusion as a changing system helps to clarify the challenge of dental restorations for both the patient and the practitioner.

Effect of sleep restriction on somatosensory sensitivity including occlusal sensation in the orofacial area

PURPOSE

To investigate the effect of sleep restriction on somatosensory sensitivity related to occlusion.

METHODS

Twelve healthy participants participated in an experimental voluntary total sleep restriction (SR) study. In a study design, they were invited to sleep as usual, normal sleep (NS) or to restrict their sleep for four nights. Following the SR night, participants were followed for 3 consecutive days including the 2 sleep nights. In NS experiment, all participants were instructed to maintain NS both nights. During all nights, actigraphy data were collected and total sleep time was estimated. On days before and after sleep conditions, all participants underwent measurements of tactile detection threshold (TDT), interocclusal detection threshold (IDT), perception of unpleasantness (POU), and the Epworth sleepiness scale (ESS).

RESULTS

As expected, total sleep time on the first night in SR experiment was significantly shorter than on the second night in SR experiment and on the first night in NS experiment (P<0.05). ESS values on Day-2 following SR experiment were significantly higher than on Day-1 and Day-3 in SR experiment and Day-2 in NS experiment (P<0.05). There were no significant differences in TDT and IDT between each day at each measurement point in both experiments. POU was significantly lower on Day-2 in SR experiment than on Day-1 and Day-3 in SR experiment and on Day-2 in NS experiment (P<0.05).

CONCLUSIONS

The present results suggest that SR affects to occlusal sensation related to POU.