Martti Helkimo

Bite force and state of dentition.

The maximal bite force and the strength of the finger-thumb grip of 125 Skolt Lapps, aged 15 to 65, was measured with a specially devised apparatus. The bite force was measured with the biting fork placed between the first molars and between the incisors, respectively. The finger-thumb grip was measured by letting the subject press the prongs of the fork between the thumb and forefinger of each hand as hard as possible. The range of inter-individual variation of the maximal bite force and finger-thumb grip was great. The mean values were higher for the males than for the females. In the males the maximal bite force thus measured in the molar region was 39 kg (382 N) and 18 kg (176 N) in the incisor region. The corresponding values for the females were 22 kg (216 N) and 11 kg (108 N). The finger-thumb grip strength for males was, on the average, 10 kg (98 N); that of the females, 7 KG (69 N). The average difference in bite force between the men and the women was larger in the group with natural teeth than in the one with complete dentures. The values found for the bite force decreased with increasing age, especially for the females. Most of this reduction with increasing age was probably due to the age-dependent deterioration of the dentition. In both sexes the bite force was notably smaller among the denture wearers than among the dentate persons. The number of natural teeth varied closely with the bite force, i.e. the greater number of natural teeth the greater the bite force.

Studies on function and dysfunction of the masticatory system

This paper gives the age- and sex distribution of symptoms of dysfunction of the masticatory system in 321 Lapps in Northern Finland. According to both an anamnestic and a clinical dysfunction index roughly the same prevalence of dysfunction was found among men as among women. The few sex differences which were found were small. Women had a significantly higher frequency of headache, pain in the neck and shoulders and fatigue of the jaws. On the average women had a worse dental state than men, who on the other hand reported luxations of the TMJ and some biting para-functions more frequently than women. The age distribution was remarkably even for most of the recorded symptoms. General symptoms as headache, general joint and muscle symptoms, however, increased in frequency with age. For some of the anamnestic variables (oral parafunctions, feeling of fatigue of the jaws and facial pain) the age group 35-44 years showed the highest frequencies. The lowest frequencies of both anamnestic and clinical symptoms...

Chewing efficiency and state of dentition. A methodologic study.

Chewing efficiency, defined as the ability to grind a certain portion of a test food during a given time, was tested in 139 Skolt Lapps, ages 14-65. 94 persons had natural teeth and the remaining 45 wore dentures (partial and/or complete). The test food was almonds. Number of chewing strokes, swallowings and chewing time was denoted. The chewing efficiency was classified after a scale from 1 to 5 where 1 meant very good and 5 very poor ability to reduce the particle size of the test food. Clear associations were found between chewing efficiency and dental state. Number of occluding pairs of teeth was closely correlated with chewing efficiency and individuals with less than 20 teeth had a higher index score than those with more than 20 teeth. The values noted for number of chewing strokes, swallowings and chewing time were smaller for those with a good chewing efficiency, but the variation was not linear and not always significant. Denture wearers had statistically significantly higher chewing efficiency score than those with natural teeth, without dentures, and needed more chewing time before swallowing.

Prevalence and severity of incisal and occlusal tooth wear in an adult Swedish population

The material consisted of 585 randomly selected dentate individuals from the community of Jönköping, Sweden, who in 1983 reached the age of 20, 30, 40, 50, 60, 70, or 80 years. The degree of incisal or occlusal wear was evaluated for each single tooth in accordance with the following criteria: 0 = no wear or negligible wear of enamel; 1 = obvious wear of enamel or wear through the enamel to dentin in single spots; 2 = wear of dentin up to one-third of the crown height; 3 = wear of dentin more than one-third of the crown height and/or excessive wear of tooth restorative material. Among the 20-year-olds 35% of the subjects had no or slight incisal or occlusal wear. The corresponding figures for the 30- to 80-year age groups were 20%, 32%, 18%, 14%, 26%, and 23%, respectively. For the age groups 20-80 years, the percentage of teeth with incisal or occlusal wear in accordance with criteria 1-3 was 13%, 20%, 16%, 24%, 23%, 23%, and 23%, respectively. Men presented more teeth with wear than women, the difference being significant for all age groups except the 20- and 60-year-olds. Among the 20-year-olds 6% had one or more teeth with wear scored 2. Among subjects aged 30 and 70 years 10% and 31%, respectively, showed tooth wear with score 2. Wear with score 3 was only found in 2% of the total population. There was an increase in the number of teeth with incisal or occlusal wear with age. With increasing age, there was also a change in distribution of wear within the dentition.

An individual tooth wear index and an analysis of factors correlated to incisal and occlusal wear in an adult Swedish population

The aim of the study was to introduce an individual tooth wear index and to use this index to investigate factors correlated to occlusal wear. The material consisted of 585 randomly selected dentate individuals from the community of Jönköping, Sweden, who in 1983 reached the age of 20, 30, 40, 50, 60, 70, or 80 years. The degree of incisal and occlusal wear was evaluated for each single tooth in accordance with criteria presented earlier. An individual tooth wear index, which made it possible to rank individuals in accordance with incisal and occlusal wear, was used as dependent variable to investigate factors related to incisal and occlusal wear. Of all factors analyzed, the following were found to correlate significantly with increased incisal and occlusal wear: number of existing teeth, age, sex, occurrence of bruxism, use of snuff, and saliva buffer capacity. Stepwise multiple regression analysis gave a total explanation factor of R2 = 0.41. It was also possible to distinguish well between groups of individuals with and without tooth wear by means of these factors.

Acupuncture and occlusal splint therapy in the treatment of craniomandibular disorders: II. A l-year follow-up study

Eighty patients, of whom 22 were men and 58 women, participated in a 1-year follow-up study. All participants in the study showed signs and symptoms of craniomandibular disorders (CMD) and had had pain for more than 6 months at treatment start. The patients were randomly assigned to either acupuncture or occlusal splint therapy. Those patients who did not respond to either of the treatment modes were offered various additional therapies. The result showed that 57% of the patients who received acupuncture and 68% of the patients treated with occlusal splint therapy benefited subjectively (p < 0.01) and clinically (p < 0.001) from the treatment over a 12-month period. No statistically significant difference was found between the two groups as to the assessment variables. Those patients who received various additional therapies after acupuncture and/or occlusal splint therapy responded favorably to additional treatment in only a few instances. The study showed that acupuncture gave positive results similar to those of occlusal splint therapy in patients with primarily myogenic CMD symptoms over a 1-year follow-up period.

Reliability and Validity of a Pressure Threshold Meter in Recording Tenderness in the Masseter Muscle and the Anterior Temporalis Muscle

The reliability and validity of an algometer pressure threshold meter (PTM) was evaluated on 45 individuals, 25 healthy volunteers and 20 patients with craniomandibular dysfunction. Tenderness upon palpation was measured at six points located on the masseter muscle, the anterior temporal muscle, and on the zygomatic arch. The validity of the PTM was evaluated by comparison of the PTM values obtained by one examiner with the finger palpation score obtained by another examiner (Part 1). A statistically significant correlation between PTM values and finger-palpation scores was found at all of the points recorded (p less than 0.05). A statistically significant difference between PTM values was obtained for the symptom-free group and the patient group. The reliability of the PTM was evaluated at six points by repeated recordings at each marked point (Part 2). High reliability coefficients (r = 0.79-0.94) were found at all the points. The study also showed that if the points were located with a certain inaccuracy (1.0 mm less than x less than 2.6 mm), the reliability coefficients were still of the same magnitude. The PTM can be recommended for evaluation of pressure pain thresholds in the masticatory system in clinical and experimental studies.

Correlations of electromyographic silent period duration and the Helkimo dysfunction index

Fifty-eight patients seen for consultation concerning mandibular dysfunction symptoms were examined utilizing the Helkimo index of dysfunction and electromyographic silent period recordings from masticatory muscles. The data collected were analyzed for correlations between the two parameters. Several significant correlations were noted between certain variables of the dysfunction index and the duration of the silent period. The mean duration of the silent period increased with increasing dysfunction index value. However, the clinical significance of this correlation is not established as long as we do not know the validity of neither the dysfunction index nor the the EMG silent period duration.

Adverse Events of Acupuncture and Occlusal Splint Therapy in the Treatment of Craniomandibular Disorders

Occlusal splint therapy and acupuncture have been found to provide positive treatment in a number of studies. As with other therapies, adverse events may occur. In this paper, adverse event refers to any reaction to a treatment besides the intended treatment effect--irrespective of any correlation between the treatment and the reaction. This reaction can be positive, as well as negative, to the patient. In the present study, 61 patients with craniomandibular dysfunction (CMD) were treated with acupuncture or occlusal splint therapy and the adverse events were carefully recorded. The results show that the profile of the adverse events differed between the two treatment modes. Acupuncture seemed to have adverse events of a more general nature, e.g., relaxed feeling, improved sleep, temporarily increased pain; whereas, adverse events of occlusal splint therapy seemed to be more locally related to the orofacial region, e.g., increased/decreased salivation and tension in the teeth. The majority of the patients responded positively to both treatment modalities. Only in a few cases did the patients consider the treatment uncomfortable. No serious adverse event or complication was observed in this study.

Recording of the retruded position of the mandible in patients with mandibular dysfunction

The precision (reproducibility) of active and passive recordings of the retruded position of the mandible was studied by two examiners on 10 patients with mandibular dysfunction symptoms. The position of the mandible was recorded with an intra-oral graphic method, before and after treatment of the symptoms. The precision of the recording was highest when the retruded position was recorded by passive hinge movement and lowest when it was recorded by active hinge movement and when recording habitual closure. Both systematical and accidental errors tended to be somewhat larger among these patients than that previously found among individuals without signs or symptoms of mandibular dysfunction. The accidental errors in antero-posterior and medio-lateral directions were the same fo both examiners and of the same magnitude before and after treatment of the symptoms. Both examiners recorded the retruded position on the average 0.20 mm more posterior after treatment than before. The results showed that because of its good reproducibility the retruded position of the mandible can be recommended as a reference position in functional analysis of occlusion and for jaw recordings also in patients with TMJ muscle-pain dysfunction symptoms. During the recording the conventional technique with passive hinge movement and a posterior pressure should be used.