Influence of dental occlusion on postural control and plantar pressure distribution

Objective: The number of studies investigating correlations between the temporomandibular system and body posture, postural control or plantar pressure distribution is continuously increasing. If a connection can be found, it is often of minor influence or for only a single parameter. However, small subject groups are critical. This study was conducted to define correlations between dental parameters, postural control and plantar pressure distribution in healthy males.

Methods: In this study, 87 male subjects with an average age of 25.23 ± 3.5 years (ranging from 18 to 35 years) were examined. Dental casts of the subjects were analyzed. Postural control and plantar pressure distribution were recorded by a force platform. Possible orthodontic and orthopedic factors of influence were determined by either an anamnesis or a questionnaire. All tests performed were randomized and repeated three times each for intercuspal position (ICP) and blocked occlusion (BO). For a statistical analysis of the results, non-parametric tests (Wilcoxon-Matched-Pairs-Test, Kruskall-Wallis-Test) were used. A revision of the results via Bonferroni-Holm correction was considered.

Results: ICP increases body sway in the frontal (p ≤ 0.01) and sagittal planes (p ≤ 0.03) compared to BO, whereas all other 29 correlations were independent of the occlusion position. For both of the ICP or BO cases, Angle-class, midline-displacement, crossbite, or orthodontic therapy were found to have no influence on postural control or plantar pressure distribution (p > 0.05). However, the contact time of the left foot decreased (p ≤ 0.001) while detecting the plantar pressure distribution in each position.

Conclusions: Persistent dental parameters have no effect on postural sway. In addition, postural control and plantar pressure distribution have been found to be independent postural criteria.     

The impact of a total hip replacement on jaw position,upper body posture and body sway

Objectives:

The purpose of this study was to examine whether, and to what extent, a total hip replacement can influence the position and the movement of the jaw, the upper body posture and body sway.

Methods:

Twenty test subjects (6 females, 14 males) participated in this study pre- and post-total hip replacement, in addition to a healthy control group of 20 subjects (5 females, 15 males). The measurements were conducted by means of an ultrasound system to measure jaw condyle position and movement of the lower jaw, a three-dimensional back scan to analyze upper back posture, and a static and dynamic force plate to measure body sway. For statistical analysis the Wilcoxon-Matched-Pairs-Test or Man–Whitney-U-Test, including a Bonferroni–Holm correction, respectively, was used.

Results:

After surgery, the mean values of the left and right jaw condyles of the test group moved posterior, and the left condyle position was located more caudally. There were no significant differences concerning the jaw position between the two groups. There was little change in upper body posture in both groups. The test group had a more anteriorly inclined thoracic spine and a less pronounced lumbar lordosis. During static body sway measurements, increased fluctuations in the test group after surgery could be seen.

Conclusion:

Differences between both groups in the pre- and post-surgical condition could be detected. These differences were more prominent when the measured body segments were more distally located with respect to the hip region.     

The effect of oscillation,low seating force and dentine surface treatment on pulpward pressure transmission during crown cementation: a laboratory study

The aim of the present research was to evaluate intra-pulpal pressure with respect to a combination of factors that are known to reduce pulpward pressure transmission in the laboratory while maintaining acceptable seating of the crowns. Thirty premolars were prepared for full crowns and individual crowns were cast. Ten teeth were etched prior to crown cementation with 100 N seating force. Crowns of groups 2 and 3 were cemented with 10 N force, after dentine sealing with bonding agent. Group two received, in addition, oscillating seating force during cementation. Pulp chamber pressure during cementation and marginal seating discrepancy after cementation were recorded. Group 1 showed significantly higher pressure mean 600 Pa and better crown seating (mean -22 microm) compared with group two (mean 144 Pa and 24 microm) and group 3 (mean 102 Pa and 44 microm) (P=0.001). Low seating forces combined with die spacer and sealing of dentinal tubules resulted in significant reduction of pressure transmitted into the pulp chamber during crown cementation. It is suggested that pre-impression sealing of dentine be considered for crown preparations on vital teeth.     

The effects of phosphoric acid, sodium hypochlorite, ferric oxalate and Scotchbond Multipurpose on the rate of pressure change across dentine: a laboratory study

The aim of this study was to investigate the consequences of dentine treatment on dentine permeability of crown preparations treated with phosphoric acid, sodium hypochlorite (NaOCl), and then ferric oxalate (Sensodyne sealant) or bis-phenol-A-diglycidyldimethacrylate (BIS-GMA) and hydroxyethylmethacrylate (HEMA) resin combination (Scotchbond Multipurpose). Thirty human premolars received full crown preparations (stage A), were then acid etched (stage B) and subsequently the pulp chamber flushed with NaOCl (stage C). They were then randomly assigned to two groups: group 1 was treated with Scotchbond Multipurpose and group 2 with 6% ferric oxalate (Sensodyne sealant) (stage D). Both groups were acid etched a second time (stage E) as the final step in the sequence. The rise in pressure in the pulp chamber because of the transmission of saline from the pressure chamber through cut dentine was recorded by a pressure transducer after each of the stages described (A to E). The mean rate of pressure change across dentine (Pa s(-1)) for each measurement point (A to E) (n = 30) were A = 2.3; B = 9.8; C = 16; D = 2.1; E = 3.1. Acid etching and NaOCl were both effective in producing significant increases in the rate of pressure change across dentine (P < 0.05). Sensodyne sealant and Scotchbond Multipurpose are both effective dentine sealants and there is no significant difference (P > 0.05) in their abilities in sealing dentine. Acid etching-sealed dentine produced a significant increase in the rate of pressure change across dentine (P < 0.05). The sealing of dentine appears to be a sensible consideration following crown preparations on vital teeth.