A retrospective study of the accuracy of Invisalign Progress Assessment with clear aligners.

The objective of this study was to detective the accuracy of model superimposition and automatic analysis for upper and lower dentition width in Invisalign Progress Assessment during the process of clear aligners. 19 cases were included in this study. Pre-treatment dental cast (T0) and post-treatment dental cast after staged treatment (T1) were available for three-dimensional model superimposition. Subsequently, movements of maxillary teeth in the horizontal plane (cross-section) after staged treatment and width of upper and lower dentition were measured by three-dimensional model superimposition in the real world and Invisalign Progress Assessment separately. Consequently, the data collected from these two methods were compared. In Invisalign Progress Assessment, movements of maxillary teeth in the horizontal plane after staged treatment was 2.31 (1.59,3.22) [median (upper quartile, lower quartile)] millimeter (mm), while in three-dimensional model superimposition, the result was 1.79 (1.21,3.03) mm. The difference between the two groups is significant (P < 0.05). Intercanine width upper, intermolar width upper, intercanine width lower, and intermolar width lower were 36.55 ± 2.76 mm, 56.98 ± 2.62 mm, 28.16 ± 1.85 mm, 53.21 ± 2.72 mm separately in Invisalign Progress Assessment and were 36.48 ± 2.78 mm, 56.89 ± 2.58 mm, 28.05 ± 1.85 mm, 53.16 ± 2.64 mm separately in three-dimensional model analysis, which was no significant difference among these groups (P > 0.05). The data from Invisalign Progress Assessment was not in parallel with what was achieved from model superimposition with palate as a reference completely. The accuracy of model superimposition in Invisalign Progress Assessment needs further investigation, whereas the accuracy of model analysis in Invisalign Progress Assessment was accurate. Thereby, results from Invisalign Progress Assessment should be interpreted with caution by the orthodontist in the clinic.

Sustained nociceptive mechanical stimulation of latent myofascial trigger point induces central sensitization in healthy subjects.

UNLABELLED: The aim of the study is to test if sustained nociceptive mechanical stimulation (SNMS) of latent myofascial trigger points (MTrPs) induces widespread mechanical hyperalgesia. SNMS was obtained by inserting and retaining an intramuscular electromyographic (EMG) needle within a latent MTrP or a nonMTrP in the finger extensor muscle for 8 minutes in 12 healthy subjects. Pain intensity (VAS) and referred pain area induced by SNMS were recorded. Pressure pain threshold (PPT) was measured immediately before and after, and 10-, 20-, and 30-minutes after SNMS at the midpoint of the contralateral tibialis anterior muscle. Surface and intramuscular EMG during SNMS were recorded. When compared to nonMTrPs, maximal VAS and the area under VAS curve (VASauc) were significantly higher and larger during SNMS of latent MTrPs (both, P < .05); there was a significant decrease in PPT 10 minutes, 20 minutes, and 30 minutes postSNMS of latent MTrPs (all, P < .05). Muscle cramps following SNMS of latent MTrPs were positively associated with VASauc (r = .72, P = .009) and referred pain area (r = .60, P = .03). Painful stimulation of latent MTrPs can initiate widespread central sensitization. Muscle cramps contribute to the induction of local and referred pain. PERSPECTIVE: This study shows that MTrPs are one of the important peripheral pain generators and initiators for central sensitization. Therapeutic methods for decreasing the sensitivity and motor-unit excitability of MTrPs may prevent the development of muscle cramps and thus decrease local and referred pain.