Influence of the Text Neck Posture on the Static Dental Occlusion.

Background and Objectives: The excessive use of smartphones for various tasks led to a new adverse postural phenomenon called text neck. The aim of this study was to investigate the effect of the text neck posture (TNP) on static occlusion by using the T-Scan III occlusal diagnostic system. Materials and Methods: Nineteen subjects (aged 20 to 24 years) were considered for this research. They had normal values for anterior overbite and overjet, Angle Class I occlusion, no posterior crossbite, and no signs or symptoms of cervical or temporo-mandibular disorders. Occlusal registrations were performed with the T-Scan III system in a normal, neutral head posture (NHP), as well as in the TNP. The investigated parameters were: occlusion time (OT), asymmetry index of the occlusal force (AOF), percent of the maximum movie force (%MMF), and the time elapsed from the last occlusal contact until the maximum intercuspation (MAT-OTB). The last three parameters were analyzed in the maximum area frame (MA) of the registrations. For the statistical analysis of the recorded data, the Wilcoxon Signed Ranks test and the Spearman's correlation coefficient were used. Results: The following values were obtained in NHP and in TNP: for AOF, 14.88 ± 10.39% and 18.04 ± 12.83%, respectively; for OT, 1.34 ± 1.84 s and 1.32 ± 1.8 s, respectively; for the %MMF, 97.5 ± 2.83% and 96.31 ± 3.17%, respectively; for MAT-OTB, 2.08 ± 1.82 s and 1.45 ± 2.3 s, respectively. There were no statistically significant differences between the static occlusal parameters measured in NHP and those in TNP. However, the high values of the AOF and OT in NHP revealed an imbalance of the occlusal force distribution between the right and left side in maximum intercuspation (MI), as well as a lack of simultaneity of static occlusal contacts. Furthermore, there was a significant, direct, and strong correlation between OT and AOF in NHP. Conclusions: The NHP should not be used as the starting position in TNP simulations in T-Scan studies, so as to avoid statistically insignificant differences between static occlusion in NHP and TNP. The healthy standing subjects, with normal occlusal relationships from the clinical point of view, revealed an occlusal instability in NHP when examined with the T-Scan.

Do different dental conditions influence the static plantar pressure and stabilometry in young adults?

BACKGROUND: Posture is influenced by many factors and dental occlusion seems to have its role on postural stabilization. Our rationale to perform the study was to find out if there are differences of static plantar pressure and stabilometric parameters depending on different dental conditions. METHODS: The observational study consisted in plantar pressure assessment and stabilometric analysis of 95 right-handed healthy volunteer subjects (mean age 22.94 ± 2.52 years) by using the PoData system. Each subject followed four measurements with open eyes: mandibular postural position, maximum intercuspation, biting on cotton rolls and maximum mouth opening. Plantar pressure was recorded on 1st and 5th metatarsal heads and heel, and was expressed as percentage of weight distribution on each foot. The recorded centre of pressure (CoP) parameters were: CoP path length, 90%confidence ellipse area and maximum CoP speed. Statistical analysis used repeated-measures ANOVA with Bonferroni posthoc analysis and Friedman test. RESULTS: Loading on the left 5th metatarsal head was significantly higher in maximum mouth opening condition when compared to maximum intercuspation and to biting on cotton rolls. The left heel loading was significantly lower in the maximum mouth opening in comparison to maximum intercuspation. The CoP path length and maximum CoP speed were significantly higher in maximum mouth opening compared to the other three conditions. Confidence ellipse area had significantly lower values in maximum intercuspation and in the biting on cotton rolls conditions compared to the mandibular postural position, and in maximum intercuspation compared to maximum mouth opening. CONCLUSION: In young adults with an optimum functional occlusion the static plantar pressure is influenced by the maximum mouth opening. An improved postural stability was recorded in maximum intercuspation (a condition used during swallowing) in comparison to mandibular postural position (a condition that allows relaxation of the masticatory muscles after functional moments).

Quantitative evaluation of dental abfraction and attrition using a swept-source optical coherence tomography system.

A fast swept-source optical coherence tomography (SS-OCT) system is employed to acquire volumes of dental tissue, in order to monitor the temporal evolution of dental wear. An imaging method is developed to evaluate the volume of tissue lost in ex vivo artificially induced abfractions and attritions. The minimal volume (measured in air) that our system could measure is 2352 µm3. A volume of 25,000 A-scans is collected in 2.5 s. All these recommend the SS-OCT method as a valuable tool for dynamic evaluation of the abfraction and attrition with remarkable potential for clinical use.

Glass fibre reinforced acrylic resin complete dentures: a 5-year clinical study.

BACKGROUND AND OBJECTIVES: The aim of the study was to establish the wear resistance of the glass fiber reinforced complete dentures comparative to the traditional acrylic complete dentures. MATERIALS AND METHODS: Complete new dentures were made to replace old fractured 'un'-reinforced acrylic dentures. The total number of dentures was 30 and woven E-glass fibre reinforcements were used in maxillary complete dentures. Unidirectional E-glass fibre reinforcements were used as partial fibre reinforcements in mandibular complete dentures. Ten complete acrylic un-reinforced dentures were used as control. The follow-up period was 5 years and the recalls were made at 6 months. RESULTS: After 5 years of wearing the new dentures, the control dentures suffered seven fractures. After 5 years all the mandibular reinforced dentures were in good shape. The maxillary complete reinforced dentures suffered four partial fractures. Fracture lines were restricted by the glass fibre net and the patients could still use their dentures. CONCLUSION: Pre-impregnated E-glass fibre nets and polymer pre-impregnated E-glass unidirectional fibres are useful in reinforcing acrylic resin complete dentures especially were heavy occlusal forces are involved. Glass fibre reinforcement will be applied on the tension side in both cases (total fibre reinforcement and partial fibre reinforcement). The reinforcement cannot replace the necessary linings and occlusal adjustments.