Influence of limited mouth opening in children on intraoral scanning accuracy: An in vitro study

Longitudinal observational digital analysis of occlusion in Hall Technique

OBJECTIVE

To evaluate volumetric changes over time in teeth treated with the Hall Technique (HT) and their opposing teeth. Secondary aims included assessing occluso-vertical dimension (OVD), temporomandibular joint (TMJ) function, and children's treatment perceptions.

METHODS

Twenty-eight children (5-9 years-old) requiring HT treatment for one first primary molar were recruited. Dental impressions were taken. Mean volume differences were digitally calculated from scanned models (Rapidform2006) between HT-treated and opposing teeth over time. Canine overlap (to measure OVD) was assessed with digital calipers. TMJ function was evaluated using Helkimo Clinical Dysfunction Index and AAPD Temporomandibular Disorders guidance. Data were collected pre-treatment (T0), immediately post-treatment (T1), at one-month (T2), and three-months (T3) after. Children's perceptions were assessed at T3.

RESULTS

The mean volume differences (mm³)±Standard error of the mean(SEM),(min-max) for HT teeth were:T0-T1:71.0 ± 3.2, (43.18 to 113.3mm³); T1-T2:10.1 ± 1.2 (0.02 to 23.52mm³); T2-T3:4.3 ± 1.0 (-4.11 to 15.43mm³) and for opposing teeth: T1-T2:6.8 ± 1.1 (-4.30 to 21.51mm³); T2-T3:0.5 ± 0.9 (-11.12 to 15.24mm³). Crowns and canine overlap measurements resolved within one month (p < 000.1), reflecting occlusion re-establishment. TMJ assessments showed mild-dysfunction in two children (8 %), resolved by T3, Children's perceptions: 26 children (93 %) "strongly agreed" or "agreed" they were happy with their crowned-tooth; one child preferred not to show it, and 26 (93 %) reported no discomfort or pain.

CONCLUSION

The volumetric changes in HT-treated and opposing teeth, along with canine overlap, indicate gradual occlusion re-establishment, primarily within one month. OVD changes resolved, there was minimal TMJ dysfunction and high patient satisfaction.

CLINICAL SIGNIFICANCE

This study demonstrates that occlusal adjustments in Hall Technique-treated teeth mainly occur within one month of crown placement, with minimal effects on TMJ function and occlusion. Results support the Hall-Technique as a child-friendly option for managing carious primary molars with high acceptance and limited clinical adverse effects.

Accuracy Analysis of Digital Models from Intraoral Scanners and 3D-Printed Casts in Children and Teenagers

PURPOSE

The aim was to analyze the accuracy of digital models and 3D-printed casts from full-arch digital impressions using two intraoral scanners (iTeroTM and PrimescanTM).

MATERIALS AND METHODS

A crossover reliability study was designed, scanning children and teenagers with iTeroTM and PrimescanTM. Accuracy was evaluated by measuring intercanine, intermolar, and ipsilateral canine-molar distances intraorally and comparing these measurements with those from plaster casts, digital models obtained with intraoral scanners, and 3D-printed casts. A paired comparison and a general linear model with a one-way repeated measures ANOVA procedure were carried out with a confidence level of 95% (p ≤ 0.05).

RESULTS

A total of 51 subjects were analyzed (mean age 12.35 ± 2.57). Statistical differences (p < 0.05) were found in the upper and lower arch regarding accuracy in comparison to intraoral measurements, except for the iTeroTM-printed cast and canine-molar upper right and intercanine lower distances (p > 0.05 for all comparisons). Regarding a comparison between reproduction methods, the plaster cast oversized the intercanine upper distance in comparison with both intraoral scanners' digital models and the PrimescanTM-printed cast (p = 0.001), but there were no differences in the lower arch (p > 0.05 for all comparisons).

CONCLUSION

Intraoral scanners reproduce tooth structures with similar accuracy to conventional methods.