Development of a Gerodontology course in Athens: a pilot study.

AIM: To describe the development of an undergraduate Gerodontology course in Athens Dental School. BACKGROUND: Because of demographic changes, undergraduate dental curricula should place appropriate emphasis on the oral care of the elderly. Therefore, the Athens Dental School Curriculum Committee authorised the development of a new Gerodontology course. METHODS: The new course was introduced in the 10th (final) semester of undergraduate studies. Teaching responsibilities were shared amongst staff from various Dental School departments and the National Health System. The course was elective and mainly didactic, consisting of seminars within the Dental School, educational visits to hospitals and geriatric day centres and elective clinical work in the comprehensive care clinic. The students evaluated the course at the end of the semester and indicated its strengths and weaknesses from their perspective. CONCLUSION: The new course was generally satisfying. Based on the experience and evaluation of the first pilot year and taking into consideration the existing barriers, we plan to improve and expand educational activities, mainly including improved methods of teaching and assessment, and more clinical assignments.

EMG activity of the masseter muscle in implant supported overdenture wearers during chewing of hard and soft food.

The influence of texture of food on the surface electromyographic (EMG) activity of the masseter muscle was investigated in a sample of mandibular implant overdenture wearers. Six experienced denture wearers (mean age 57.8 years) with mandibular overdentures supported by two implants, consented to participate in this study. Fresh raw carrots and peeled apples of similar size and weight were chosen as representing hard and soft food, respectively. The findings were in line with those earlier reported in dentate subjects and complete denture wearers in that harder foods require higher chewing rates, higher EMG activity and higher relative contraction times, accompanied by shorter cycle durations. It was also concluded that rehabilitation with implant retained mandibular dentures may result in more regular chewing patterns with higher electrical activity of the masseter muscles, thus providing improved chewing function and comfort.

Bilateral variation of the masseteric myotatic reflex and the silent period in young humans.

Increased bilateral differences in jaw reflexes have been considered as pathological findings. The aim of this study was to investigate the normal variation between sides in the jaw jerk and the silent period and determine the range of its boundaries, using the present experimental set-up. Electromyographic data were simultaneously recorded from the right and left masseter muscles by surface electrodes, using a computerized recording and analysis system. The reflexes were elicited by chin taps during mandibular rest and at moderate intercuspal clenching in 20 healthy dentate adults (10 males and 10 females) with a mean age of 26 years. The reflexes were always elicited bilaterally and no overall significant differences were observed between sides for occurrence, latency, duration and amplitude of the jaw jerk and for the latency and duration of the silent period (P > 0.05). However, in the individual analysis significant bilateral variation was occasionally recorded, particularly for the jaw jerk at rest and mainly in the amplitude measurements. On the other hand, in the silent period duration measurements individual variation was very limited. Bilateral individual latency differences for the jaw jerk did not exceed 1 ms at rest (x = 0.3 +/- 0.3 ms) and 0.7 ms at clench (x = 0.3 +/- 0.2 ms), while latency differences for the silent period did not exceed 0.8 ms for the early type (x = 0.4 +/- 0.2 ms) and 4.8 ms for the late phase of depression (x= 1.9 +/- 1.7 ms). Bilateral differences for the silent period duration did not exceed 7.1 ms (x = 2.2 +/- 2.3 ms) in the early type (simple + early phase of combined types) and 3.3 ms (x = 1.5 +/- 0.9 ms) in the total duration of the combined types.

Normal side-to-side variation of the exteroceptive suppression of masseter muscle in young dentate adults.

Previous studies have shown that various stimuli applied in the orofacial region, evoke bilateral inhibitory responses in the jaw elevator muscles. The exteroceptive supression (ES) of the masseter muscle after electrical stimulation of the mental nerve, often appears as a double phase of inhibition interrupting the voluntary sustained contraction of the muscle. The aim of the present study was to investigate the normal bilateral variation of the masseteric ES in a control group of 20 healthy dentate adults, and to determine the range of its boundaries. The reflex was elicited by electrical stimulation of the mental nerves, during maximum intercuspal clenching. Generally, the overall mean values for the latencies and durations were in line with those reported in previous investigations, while no significant differences were found between the left and the right masseter muscles, regardless of the side of stimulation. However, in the intra-individual analysis, significant bilateral variation was occasionally recorded, particularly in the latency and duration of the late exteroceptive suppression. It was concluded that the exteroceptive suppression of the masseter muscle is a repeatable and clear bilateral reflex response, although an increased number of observations is recommended in normal subjects, before its use could be extended for diagnostic purposes.

Socio-medical condition and oral functional status in an older institutionalised population.

OBJECTIVES: To investigate the association between the general medical condition, the socio-economic status, and some factors related to the functional status of the stomatognathic system. DESIGN: A survey in an elderly population. SUBJECTS: 257 older adults, with a mean age of 83.7 years. SETTING: Residential homes for the elderly. INTERVENTION: Examination of the medical records on the overall health and the drugs consumed, a structured interview on the socio-economic status, the complaints for xerostomia, the subjective chewing difficulties, and a clinical evaluation of the number of natural teeth and the number of posterior occluding pairs of teeth contacts (premolars and molars). RESULTS: Multiple pathology and polypharmacy were recorded. 25% of the residents had no occluding posterior tooth contact (natural or prosthetic) and 62% were edentulous. 43% of the residents reported complaints for xerostomia, and 46% for chewing difficulties when eating specific food types. Xerostomic feelings and chewing problems were not related to age. Chewing difficulties were not related to the number of natural teeth, but to the number of posterior occluding teeth contacts, natural or prosthetic (less than two). From all medical conditions examined, only the psychiatric disorders were significantly related to dental status (p < 0.05). Moreover, the number of remaining natural teeth was related to socio-economic status, while the number of posterior occluding teeth contacts was also inversely related to the duration of institutionalisation (p < 0.05). CONCLUSIONS: Psychiatric disorders, low socio-economic status and increased duration of institutionalisation were most closely related to poor dental status. The presence of more than two posterior occluding teeth contacts, natural or prosthetic, benefit the very old patient in terms of reduced subjective chewing difficulty. A formal oral care delivery system for the institutionalised elderly, and particularly for those suffering from psychiatric disorders, is imperative.

Surface EMG activity of the masseter muscle in denture wearers during chewing of hard and soft food.

Previous studies mainly on dentate subjects, have clearly shown that food texture affects the various chewing parameters. The purpose of this investigation was to study the influence of food texture on the surface electromyographic (EMG) activity of the masseter muscle in a sample of denture wearers. Nine experienced denture wearers (mean age of 68.7 years) with clinically satisfactory dentures consented to participate in this study. Carrots and peeled apples cut into equally sized pieces were chosen as representing a hard and a soft food respectively. The parameters studied from the raw and integrated EMG recordings were: chewing rate, mean peak RMS activity, chewing cycle and chewing burst duration and relative contraction period. The findings were in line with those earlier reported on dentate subjects, in that harder foods require higher chewing rates, higher electrical activity of the masseter muscle and higher relative contraction periods, accompanied by shorter cycle durations. Most of these differences were statistically significant (P< 0.05) as tested by paired t-test. Moreover a strong inverse correlation was found between chewing rate and cycle duration (r = -0.92, P < 0.05). We concluded that the texture of food has an obvious effect on all the studied parameters of EMG activity, and that those adjustments to food consistency are probably due to a combined powerful peripheral input mediated through receptors, other than the periodontal ones.

Jaw reflexes in healthy old people.

OBJECTIVE: to investigate variations in the masseteric myotatic reflex (jaw-jerk) and the silent period from the 5th to the 9th decades of life. SUBJECTS AND METHODS: electromyographic data were recorded from the masseter muscle of the preferred chewing side by surface electrodes, using a computerized recording and analysis system. Chin taps were applied with a neurologist's hammer during mandibular rest and at 40% intercuspal clenching in 30 healthy people aged from 49 to 87 years. The influence of age, gender and silent period type were analysed by multiple regression analysis (P < or = 0.05). RESULTS: even in the very old subjects all reflexes were elicited, at least once. However, with increasing age the overall occurrence of the jaw-jerk reflex at rest (%) and its amplitude, at rest and at clench, were reduced, while its latency at rest was significantly increased (P < or = 0.05). No age effects were recorded in most parameters of the jaw-jerk reflex at clench and in the silent period. Women showed a tendency for reduced latencies of the jaw-jerk and the early silent period and increased silent period duration (P < or = 0.05). They also had a steeper decline in myotatic reflex activity, particularly at rest. CONCLUSION: simple masseteric reflex activity is maintained until very old age, particularly when elicited during contraction of the jaw elevators.

Re-examination of the surface EMG activity of the masseter muscle in young adults during chewing of two test foods.

The purpose of this study was to investigate the effect of the texture of food on the masseter EMG activity during chewing. Fresh raw carrots and non-adhesive chewing gums of similar size and weight were used as representing a hard and a soft food respectively. The mean values for the IEMG activity, the duration of the chewing cycle, the chewing rate and the relative contraction time during chewing were significantly higher for the carrots while no significant difference was found in the chewing burst duration between the two test foods. Finally a strong inverse correlation was found between chewing rate and cycle duration. It was concluded that the texture of food has an obvious effect on EMG activity during chewing and that adjustments to changes in food consistency are made mainly by altering the chewing rate, the duration of the chewing cycle and the IEMG activity.

Cephalometric evaluation of the changes in mandibular symphysis after 7 years of denture wearing.

OBJECTIVE: To evaluate changes in mandibular symphysis during 7 years of complete denture wearing following extraction of natural anterior teeth. DESIGN: Comparison among measurements taken at four different occasions in a prospective cephalometric study. SETTING: The study was conducted at the Dental School of Athens University. SUBJECTS: 10 complete denture wearers (5 women, 5 men) with average age of 53.2 years, at the beginning of the study. MEASURES: Linear and area measurements of the mandibular symphysis. RESULTS: The overall reduction in the anterior mandibular height was 7.87 mm and in the mandibular symphysis area 54.8 mm2 (p < 0.05). Females presented higher total average reduction in both variables tested, and more rapid bone loss during the first two years of denture wear, compared to men. Superimposition of the tracings revealed considerable individual variation in mandibular symphysis changes. CONCLUSION: Results are in line with the findings of other authors indicating continuous reduction and dramatic inter-subject variation in the mandibular alveolar bone, following extraction of natural teeth and wearing of complete dentures.

Variation in the masseteric silent period in older dentate humans and in denture wearers.

The masseteric silent period was elicited by chin taps at 40% clenching in the masseter muscle of the preferred chewing side in 22 younger dentate individuals, in 22 older dentate individuals, in 22 older experienced denture wearers and in 7 older inexperienced denture wearers. One simple and three combined types of silent period (combination of early and late phases of depression) were recorded in all groups. An early silent period was always elicited, the only exception being in some inexperienced denture wearers. Both the age and the extent of rehabilitation with dentures in the trained denture wearers affected reflex latencies (p < 0.05), while the variation in duration was not significant (p > 0.05). The duration of the silent period was, however, affected by the type of silent period, thus by the measuring technique (p < 0.05). Increased variation was observed in the inexperienced denture wearers, who were in a period of adaptation.

The masseteric jaw-jerk reflex in older dentate subjects and edentulous denture wearers.

The aim of the present study was to investigate any variations in the jaw-jerk reflex in edentulous subjects wearing complete dentures, compared to an age and sex-matched dentate group. The reflex was elicited by chin taps in 22 older dentate subjects with mean age 61.3 years and in 22 denture wearers with mean age 63.1 years. Surface electromyographic recordings were obtained from the masseter muscle of the preferred chewing side during mandibular rest and at moderate clenching (40% of the individual maximum clenching masseteric EMG activity). A jaw-jerk reflex was recorded in all subjects at least once, and its occurrence during clenching was reduced compared to rest. The occurrence of the reflex was however increased in the denture wearers in both experimental conditions, while minor differences were observed in the values for latency, duration and amplitude between the two dental status groups. These results suggest that under the present experimental conditions the periodontal ligament receptors might inhibit reflex activity. Multiple sensory interactions are expected in denture wearing. However a particular source of sensory feedback is provided by the stimulation of mucosal receptors from the acrylic denture base. Since the occurrence of the jaw-jerk at clench in the denture wearers was also reduced compared to the rest experiments, a potential inhibitory effect of the mucosal receptors can be speculated. According to the findings in the present study the loss of teeth and the rehabilitation with complete dentures do not severely disrupt the reflex activity investigated.

Random variation in the masseteric silent period after chin taps.

Although the silent period duration has often been evaluated as a potential indicator of stomatognathic system dysfunction, there is still some uncertainty as to its normal biologic variation. This study investigated the subject variation in the silent period in a group of 22 young and healthy subjects under standardized conditions. Electromyographic recordings were obtained from the masseter muscle at 40% clenching after chin taps. Four different patterns of the silent period were recorded: one simple and three combined. Although the latencies of the early and late phases of depression were generally consistent, the results for duration were more variable and depended on the pattern of the silent period.

EMG study on the effect of ageing on the human masseteric jaw-jerk reflex.

The effect of age on the masseteric jaw-jerk reflex was investigated in 22 young (11 males and 11 females with mean age 23.2 years) and 22 older dentate subjects (11 males and 11 females with mean age 61.3 years). Electromyographic (EMG) recordings were obtained, after chin taps, from the relaxed masseter muscle of the preferred chewing side, by use of a computerised recording and analysis system. With increasing age the occurrence of the reflex was reduced, the latency was increased, while the amplitude was decreased. Those findings are probably related to the general age related changes in the muscular tissue, the sense organs, the peripheral nerves and especially the central nervous system. Increased biological variance was also observed in the older subjects, as in most aspects of performance in the latent years. Furthermore, the effects of ageing were generally similar in men and women. The age-related decrement in the monosynaptic reflex response is indicative of a generalised decline in the motor performance of the stomatognathic system and the decreased ability of the older dental patient to easily adapt to any dramatic changes in the sensory input.

The influence of gender on the masseter electromyographic jaw-jerk reflex in young human subjects.

The purpose of this study was to investigate the effect of gender on the masseteric jaw-jerk reflex, evoked in a sample of nine male and nine female young subjects. Electromyographic jaw-jerk recordings elicited by chin-taps in the relaxed masseter muscle of the preferred chewing side, were obtained using a computerized recording and analysis system. In both groups, a jaw-jerk reflex was recorded in 95.56% out of the total number of chin-taps. The mean latency was significantly shorter in the females (5.75 ms) than in the males (6.14 ms, P = 0.0045), while the amplitude of the reflex was significantly higher in the females (P = 0.0005). No significant differences were found in the mean duration between males (6.86 ms) and females (6.73 ms). It was concluded that sex variation should be taken into consideration in the interpretation of the jaw-jerk reflex.

Changes in mandibular alveolar bone and anterior face height after four years of complete denture wearing.

A 4-year cephalometric study was conducted on 14 wearers of complete dentures to quantify the anterior alveolar bone loss and to study any associated changes in the maxillomandibular relationships. Both the occlusal and the rest-face heights underwent a significant decrease while a parallel tendency for anterior rotation was recorded. The continuous bone loss in the anterior mandible had a significant relationship to the reduction of the anterior face height.

Reproducibility of the human masseteric jaw-jerk reflex in association with the menstrual cycle.

The jaw jerk was elicited by chin taps in the relaxed masseter muscle of the preferred chewing side in five young females. Recordings were made during three randomized sessions and under standardized conditions: two sessions between the seventh and the 15th day of the female menstrual cycle and the third within the last 5 days of the cycle. Both latency and duration of the reflex were generally reproducible over time. Individual between-session variation was occasionally present, with a general tendency for lower values in the end-cycle session, but this did not affect the overall results. Systematic subject variation, such as central excitatory-state variance of the timing of the experiments, and possibly some other uncontrolled technical error, may have contributed to the observed variation.

Anterior digastric muscle responses to sudden unloading of the mandibular elevator muscles in younger and older adults.

The digastric motor responses in the unloading reflex were investigated in a sample of 10 younger and eight older dentate subjects. The occurrence of the pre-collapse digastric activity (PDA) and the reflex events (burst of activity) following the mandibular unloading (DB) were studied separately. PDA was nearly consistent in half of the subjects of both groups. DB was clearly identified in 60% of the younger subjects, but in 54.2% of the older subjects. The mean latency of DB found in the younger subjects was 32.4 +/- 9.5 ms but 34.5 +/- 8.8 ms in the older subjects. For the latencies found we can infer that they are related to polysynaptic pathways. Also a slight tendency for decreased frequency of occurrence and increased latencies of DB is observed in the older age group.

Oral health status, treatment needs and demands of an elderly institutionalised population in Athens.

Oral health status, treatment needs and demands were investigated among 242 elderly people (63 males and 179 females) living at the largest residential home in Athens. The mean age of the sample was 83.8 years (82.8 males and 84.1 females). The oral health status was generally poor, 64.4% of the population were edentulous while 16.1% of them lacked dentures in both jaws. 43.2% of the subjects presented with denture-induced pathology of the oral mucosa, requiring either conservative or surgical treatment. The dentate subjects had an average of 12.3 teeth with 4.2 teeth requiring extraction and 2.2 teeth with coronal restorable caries. The mean Root Caries Index was found to be 18.5%. The assessment of the periodontal treatment needs according to the CPITN revealed that 9.3% of the dentate subjects needed only oral hygiene instruction, 61.5% professional scaling and 20.9% more complex periodontal treatment. Although the total percentage of subjects needing some form of dental treatment was 85.1%, only 34% of them felt that they required it and only 13.1% had tried to obtain it.

The effect of intercuspal clenching on the masseteric jaw-jerk reflex in humans.

Although several studies have been conducted regarding the jaw-jerk reflex and its various modifying parameters, the effect of intercuspal clenching still remains poorly understood. Evidence of both excitatory and inhibitory influences of periodontal receptors on jaw muscle activity has been reported. It is also suggested that a level of background activity in the stimulated muscle facilitates the reflex response. It was therefore the purpose of this study to investigate the effect of simultaneously activated periodontal receptors on the various parameters of the masseteric jaw-jerk reflex during moderate masseter muscle activation. Electromyographic recordings were obtained from the masseter muscle of the preferred chewing side at rest and at intercuspal clenching in 10 men, by use of a computerized recording and analysis system. In the clenching trials the level of muscular activity was set at 40% of the maximum value obtained through visual feedback. The results showed that at 40% clenching the occurrence of the reflex was reduced as compared with that obtained at rest. Moreover, when present during clenching, its latency and duration were shorter, whereas its amplitude was higher. It was suggested that the simultaneous activation of periodontal receptors may occasionally inhibit the masseteric monosynaptic excitation.

Digastric muscle response as a function of knowledge of the task to be performed.

Whether the motor programme executed by the digastric muscles during a forceful bite is modified according to a subject's expectation that the resistance between the teeth will change was investigated. There were two experimental conditions: (1) tracking a ramp (drawn on an oscilloscope screen) by biting (isometrically) on a force transducer and holding it at 120 N, and (2) tracking the same ramp with a sudden unloading at 100 N. There were two groups of experiments: (1) control experiments in which subjects underwent a sudden and unexpected unloading of the jaw, and (2) experiments in which subjects were previously informed whether or not there was to be an unloading. In all experiments the subjects co-contracted their digastric muscles during the bite as compared to the state at rest. The subjects' responses fell into the three different types: (i) those who varied the level of tonic digastric activity only as a function of the experimental condition, (ii) those who co-contracted the digastric muscles at the same time as the masseter muscles, and (iii) those who changed the contraction pattern of the digastric muscles as a function of the experimental condition. If modulation of the digastric muscles occurred this is a 'feedforward' strategy mainly based on immediate past performance.