Cerebral blood flow and oxygen metabolism in rett syndrome

Positron emission tomography was performed on six patients with Rett syndrome to investigate cerebral blood flow and oxygen metabolism, and the results were compared with the concurrent clinical status of the patients. The cerebral metabolic rate of oxygen (CMRO2) was low in five patients, and oxygen extraction fraction was low in four patients; both had a tendency to decline with advancing age. Although the cause is unknown, it is suggested that impaired oxidative metabolism exists in Rett syndrome. An analysis of the distribution among brain regions showed that the ratios of values for the frontal cortex to those for the temporal cortex for both cerebral blood flow and CMRO2 were lower than those for the controls, which may indicate the loss of hyperfrontality in Rett syndrome.     

Cerebral oxygenation changes in response to post-hemodialysis standing

Journal of Artificial Organs - Few reports have examined the association between changes in cerebral oxygenation and clinical factors, including blood pressure (BP), upon standing after...     

Effect of prosthetic restoration on masticatory function in patients with shortened dental arches: a multicentre study

The aim of this multicentre study was to investigate the effect of prosthetic restoration for missing posterior teeth on mastication in patients with shortened dental arches (SDAs). Partially dentate patients who had an intact teeth in anterior region and missed distal molar(s) (2–12 missing occlusal units) classified as Kennedy Class I or Class II were recruited from seven university‐based dental hospitals in Japan. Of the 125 subjects who underwent baseline (pre‐treatment) and follow‐up/post‐treatment evaluation, 53 chose no replacement of missing teeth and 72 chose treatment with removable partial dentures (n = 53) or implant‐supported fixed partial dentures (n = 19). Objective masticatory performance (MP) was evaluated using a gummy jelly test. Perception of chewing ability (CA) was rated using a food intake questionnaire. In the no‐treatment group, mean MP and CA scores at baseline were similar to those at follow‐up evaluation (P > 0·05). In the treatment group, mean MP after treatment was significantly greater than the pre‐treatment mean MP (P < 0·05). However, the mean perceived CA in the treatment groups was similar at pre‐ and post‐treatment (P > 0·05). In a subgroup analysis of subjects in the treatment group, subjects with lower pre‐treatment CA showed a significant CA increase after treatment (P = 0·004), but those with higher pre‐treatment CA showed a significant decrease in CA (P = 0·001). These results suggest that prosthetic restoration for SDAs may benefit objective masticatory performance in patients needing replacement of missing posterior teeth, but the benefit in subjective chewing ability seems to be limited in subjects with perceived impairment in chewing ability before treatment.     

Oral health‐related quality of life in patients with non‐metal clasp dentures: a randomised cross‐over trial

We investigated the efficacy of non‐metal clasp dentures (NMCDs) with regard to the oral health‐related quality of life (OHRQoL) and compare the findings with those for conventional metal clasp‐retained dentures (MCDs). This single‐centre, randomised controlled, two‐phase, open label, cross‐over trial included 28 partially dentate individuals. The patients were randomised to receive MCDs followed by NMCDs, or the opposite sequence (n = 14 in each group); each denture was worn for 3 months. OHRQoL was evaluated using the Oral Health Impact Profile‐Japanese version (OHIP‐J) at entry (T‐entry; before treatment with the first denture) and at 3 months after treatment with each denture (T3). An examiner evaluated denture stability, oral appearance and surface roughness before denture delivery (T0) and at T3 and denture hygiene at T3. A total of 24 patients completed the trial. There were no complications related to the dentures, abutment teeth or denture‐bearing mucosa during the follow‐up periods for both dentures. The mean OHIP summary score was lower for NMCDs than for MCDs, and the difference (9 points) was greater than the minimal important difference (6 points), indicating the difference was clinically relevant. The effect size was medium (0·70). Statistical analyses with linear mixed models found a significant effect of the denture type on the OHIP summary score and scores for the Oro‐facial appearance, Oro‐facial pain and Psychological impact domains (NMCD < MCD; P < 0·05). The results of our study suggest that NMCDs allow for better OHRQoL compared with MCDs.     

Influence of intra‐oral sensory impairment by anaesthesia on food comminution and mixing in dentate subjects

Sensory input from sensory receptors regarding food morsels can affect jaw motor behaviours during mastication. The aim was to clarify the effects of intra‐oral sensory input on the food‐comminuting and food‐mixing capacities of dentate subjects. Eleven dentate subjects without sensory dysfunction in their oro‐facial region participated in this study. Local anaesthesia was achieved on the periodontal structures and on the oral mucosa of the subjects' preferred chewing side by injecting a lidocaine solution with adrenalin. At baseline (control) and after anaesthesia, data on the subjects' food‐comminuting and food‐mixing capacities were gathered. The food‐comminuting capacity was quantified by measuring the degree of pulverisation of peanuts (objective hardness; 45·3 [Newton, N]) after a prescribed 20 chewing strokes. The food‐mixing capacity was measured as the degree of immixture of a two‐coloured paraffin wax cube after 10 chewing strokes. Wax cubes of three different hardness levels were used (soft, medium and hard: 20·3, 32·6 and 75·5 [N], respectively) and were chewed in random order. After anaesthesia, the subjects' food‐comminuting capacity significantly decreased (P < 0·001), as did the food‐mixing capacity for each hardness level of the wax cubes (P < 0·01). A significant correlation was observed between the objective hardness values and the anaesthesia effects for the food‐mixing capacity (P < 0·05), indicating that after anaesthesia, deterioration of the mixing capacity increased as the hardness increased. In conclusion, intra‐oral sensory input can affect both food‐comminuting and food‐mixing capacities.     

Does oral dryness influence pressure pain sensitivity in the oral mucosa of removable denture wearers?

Clinical Oral Investigations - This study aimed to determine if oral dryness is associated with oral pain sensitivity in removable denture wearers. The pressure pain threshold (PPT) in the mucosa...     

Association between food mixing ability and mandibular movements during chewing of a wax cube

The purpose of this study was to clarify whether masticatory movements during chewing of a wax cube associate with food mixing ability. Twenty-six dentate subjects (mean age 25.3 years) were directed to chew a two-coloured paraffin wax cube for 10 strokes on preferred chewing side. Mixing Ability Index (MAI) was determined from the colour mixture and shape of the chewed wax cube. MAI was employed as an estimate of food mixing ability. Mandibular movements during chewing of the wax cube were recorded using a six-degrees-of freedom jaw movements recording system, and motion of a lower incisal point of the mandible was computed. Twelve parameters of masticatory movements in relation to mandibular excursion, angle, velocity, cycle duration, duration of each phase were measured for each masticatory cycle. In addition, unilateral maximum biting was performed, and the maximum force during biting was measured using a force-transducer. A multiple regression analysis identified vertical amplitude, closing duration, closing angle and maximum bite force as significant predictors accounting for 63% of inter-subject variation (adjusted R(2)) in the MAI (P < 0.05). Only some parameters of masticatory movements seem to have an influence on the MAI in dentate subjects.