An analytical approach to 3D orthodontic load systems

Development of a Chewing Robot With Built-in Humanoid Jaws to Simulate Mastication to Quantify Robotic Agents Release From Chewing Gums Compared to Human Participants

Medicated chewing gum has been recognised as a new advanced drug delivery method, with a promising future. Its potential has not yet been fully exploited because currently there is no gold standard for testing the release of agents from chewing gum in vitro. This study presents a novel humanoid chewing robot capable of closely replicating the human chewing motion in a closed environment, incorporating artificial saliva and allowing measurement of xylitol release from the gum. The release of xylitol from commercially available chewing gum was quantified following both in vitro and in vivo mastication. The chewing robot demonstrated a similar release rate of xylitol as human participants. The greatest release of xylitol occurred during the first 5 minutes of chewing and after 20 minutes of chewing only a low amount of xylitol remained in the gum bolus, irrespective of the chewing method used. Saliva and artificial saliva solutions respectively were collected after 5, 10, 15 and 20 minutes of continuous chewing and the amount of xylitol released from the chewing gum determined. Bioengineering has been implemented as the key engineering strategy to create an artificial oral environment that closely mimics that found in vivo. These results demonstrate the chewing robot with built-in humanoid jaws could provide opportunities for pharmaceutical companies to investigate and refine drug release from gum, with reduced patient exposure and reduced costs using this novel methodology.

The mechanics of dental occlusion and disclusion

BACKGROUND

The mechanical environment associated with occluding teeth is the foundation for a wide range of research topics, clinical practice and dogma, product development and marketing, and medico-legal issues. The purpose of this study was to experimentally examine the relationships between occlusal factors and their impact on the associated contact forces.

METHODS

Matching pairs of 0°, 20°, 33° and 40° cusp first molar denture teeth were placed into Class I, II and III molar relationships. As the teeth were brought together into occlusion and then separated, the loads experienced by the mandibular tooth were continuously measured by a load cell that was supporting it.

FINDINGS

Loess smoothing splines were fitted to all data curves to calculate 95% confidence intervals. All lateral force magnitudes and directions were statistically different when compared between classes of occlusion, cusp angles, and occlusion vs. disclusion. Noteworthy counterintuitive observations were that the lateral contact force components were generally higher during disclusion than occlusion, the peak lateral force magnitudes did not always occur when the occlusal force was maximum, and the lateral contact force component magnitude can be larger than the occlusal force.

INTERPRETATION

Wedging and friction account for these unexpected results. The data indicate that each occlusion/disclusion cycle is characterized by complex transient loads that may impact wear facet and non-carious cervical lesion formation, implant and restorative failures, various aspects of occlusal trauma, and the concept of axial occlusal loading.

The effects of salivas on occlusal forces

Contacting surfaces of opposing teeth produce friction that, when altered, changes the contact force direction and/or magnitude. As friction can be influenced by several factors, including lubrication and the contacting materials, the aim of this study was to measure the occlusal load alterations experienced by teeth with the introduction of different salivas and dental restorative materials. Pairs of molar teeth were set into occlusion with a weighted maxillary tooth mounted onto a vertical sliding assembly and the mandibular tooth supported by a load cell. The load components on the mandibular tooth were measured with three opposing pairs of dental restorative materials (plastic denture, all-ceramic and stainless steel), four (human and three artificial) salivas and 16 occlusal configurations. All lateral force component measurements were significantly different (P < 0·0001) from the dry (control) surface regardless of the crown material or occlusal configuration, while the effects of the artificial salivas compared to each other and to human saliva depended on the crown material.