RESUMEN
OBJECTIVE/AIMS: The aim of this study was to measure continuously the intraoral pH and temperature of healthy individuals to investigate their diurnal variations. MATERIALS AND METHODS: Seventeen participants (mean age, 31±9 years) wore a custom-made intraoral appliance fitted with a pH probe and thermocouple for two sets of 24 h, while carrying out normal daily activities including sleep. The continuous changes in intraoral pH and temperature were captured using a sensor placed on the palatal aspect of the upper central incisors. The collected data were categorised into different status (awake and sleep) and periods (morning, afternoon, evening and night). Both quantitative and qualitative analyses were conducted. RESULTS: The intraoral pH change was found to show a distinctive daily rhythm, showing a 12-h interval between maximum (7.73) and minimum (6.6) pH values. The maximum and minimum values were found to repeat after 24 h. The mean pH over 48 h (two sets of 24 h) was found to be 7.27 (±0.74). There was significant difference found in pH when subjects were awake and asleep and different periods during the day (P<0.001). The mean intraoral temperature was 33.99 °C (±4.9), with less distinctive daily rhythm compared with pH. There was a significant difference found in temperature depending on the time of the day, except between morning and afternoon (P=0.78). CONCLUSION: Our results showed that there is a distinctive daily, circadian-like pattern in intraoral pH variation over a 24-h period, which has been considered as one of the risk factors in sleep-related dental diseases.
RESUMEN
PURPOSE OF STUDY: The severity of tooth wear is known to have an association with intraoral pH and temperature depending on the site. OBJECTIVE: To compare the intraoral pH and temperature between the maxillary and mandibular arch. METHODS: Fourteen participants (mean age=25.8 years) wore a custom-made intraoral appliance fitted with a pH probe and thermocouple for 24 h while carrying out normal activities including sleep. All participants wore a maxillary appliance; four participants repeated the process and wore the mandibular appliance. Measurements were taken from the palatal aspect of the upper central incisors and lingual aspect of the lower canines. Both qualitative and quantitative statistical analyses were conducted. RESULTS: The mean intraoral pH from the maxilla was 7.32 (±0.52) and 7.07 (±0.26) for the mandible. During daytime, there was no statistical significance difference between the two arches (P=0.12). During sleep, there was a significant difference (P<0.001) between the mean pH of the maxilla, 7.0 (±0.46), and mandible, 6.46 (±0.31). The fluctuation patterns of pH and temperature from both arches were similar, but the maxilla showed more variations. The mean temperature from the mandible was slightly higher (36.18 °C (±0.96)) than the maxilla, 33.12 °C (±5.51) during daytime; however, there was no statistically significance difference in temperature between the arches during daytime (awake) or sleep (P=0.27). CONCLUSION: The results showed that there is significant difference in mean intraoral pH between the maxilla and the mandible during sleep, but not during the day and this difference may be associated variations in tooth wear between the arches.
RESUMEN
BACKGROUND: The need for continued refinement of animal models in orthopaedic studies persists despite decades of research. OBJECTIVE: This study investigates the merits of deer bone in comparison to the more commonly used pig and sheep bone as an animal model for the human femur. METHOD: A morphological and biomechanical comparison of deer, pig and sheep rear femurs to those of the human femur is presented. Morphological parameters measured include bone length, cortical and medullary diaphyseal diameters, cortical thickness, cortical cross-sectional area and bone density along the diaphysis. Biomechanical tests included whole-bone four-point flexure tests to determine the bending stiffness (N/mm), Young's modulus of bending (GPa), and ultimate strength in bending (MPa). In addition torsional stiffness (Nm/degree) as well as mid-diaphyseal cortical compressive elastic modulus (GPa) and strength (MPa) is investigated. RESULTS: On average, deer bone was found to be the least dissimilar from human femur. However, no single bone type consistently resembled the human femur. CONCLUSION: Deer femora should be considered a suitable animal model for the human femur.
