Krishan K. Kapur

Clinical comparison of masticatory performance and electromyographic activity of patients with complete dentures, overdentures, and natural teeth

In this study, which is the first of its kind, it has been shown that overdenture patients, when compared to complete denture patients, while chewing a test food for a constant number of strokes, expended an equivalent amount of muscle effort, chewed more slowly and efficiently, and evidenced significantly better masticatory performance by producing an increased volume of fine test food particles. These findings provide a sound justification for the extra effort required to retain some natural teeth to provide overdenture services to patients. The fact that patients can masticate food more efficiently with overdentures than with complete dentures justifies the increased cost and time involved in their construction. The longitudinal effects that overdentures have on the basic physiopathologic processed involved in the progression of ridge resorption and the advantages of maintaining periodontal proprioception also should be studied.

PAROTID FLUID COMPOSITION IN HEALTHY AGING MALES

Publisher Summary This chapter explores the link between age and parotid saliva composition in healthy aging males. The composition of human parotid saliva is primarily dependent on the acinar and duct cell secretory and resorption capacity. In an experiment described in the chapter, a vacuum-maintained metal collection device was positioned over the orifice of Stensens duct. The subject was given a sour-lemon flavored lozenge, and a one-minute acquaintance interval of stimulation was permitted to clear the collection apparatus and to allow the gland to adjust to the stimulus. The electrolyte composition of human parotid saliva is dependent upon the net flux of water and electrolytes that are transported across the epithelium at any particular secretory rate. The decrease in parotid calcium might reflect a variety of physiologic conditions associated with aging. While there is little information relative to general body calcium metabolism to provide an insight regarding the physiological processes responsible for this change, the possibility exists that the decreasing calcium levels are associated with age-related changes in protein synthesis.

Studies of biologic parameters for denture design. Part II: Comparison of masseter muscle activity, masticatory performance, and salivary secretion rates between denture and natural dentition groups

Bilateral masseter muscle activities exerted during masticatory and salivary secretion rate tests of a group of 18 denture wearers were compared with a group of eight persons with 26 or more natural teeth. Denture wearers applied 22% to 39% of the muscle force applied by the ND group to chew peanuts or carrots and showed markedly lower masticatory performances. The average muscle activity was higher for chewing peanuts than carrots in the ND group but was similar for both test foods in the AD group. Motor discrimination seems to be intact in denture wearers, but their inability to tolerate high masticatory pressures may prevent them from exerting discriminatory forces comparable to those applied by persons with natural dentition when chewing relatively tough foods of varying hardness. The results indicate that the reduced muscle force applied by denture wearers is another important factor that contributes to their diminished chewing ability. Even though the denture wearers were older and applied less muscle activity during chewing, they produced slightly higher rates of stimulated parotid saliva than the ND group. This supports our previous findings and further indicates that the mucosal stimulation of dentures compensates for decreased muscle activity and absence of periodontal receptor stimulation for producing saliva in healthy denture wearers.

Studies of biologic parameters for denture design. Part III: Effects of occlusal adjustment, base retention, and fit on masseter muscle activity and masticatory performance

EMG recordings of ipsilateral and contralateral masseter muscles and standardized masticatory performance tests were made in 20 denture wearers before and after modifications were made to their clinically unsatisfactory dentures. The improvement of retention and stability by correction of gross occlusal prematurities and by the use of a denture adhesive or base reline with a soft tissue-conditioning material did not significantly alter the chewing performance or muscle activity during mastication in denture wearers. The results support our previous findings that the influence of denture factors on chewing ability of denture wearers is limited. To avoid variations in EMG activity caused by changes in electrode positions, all tests for a given subject were made at the same sitting. Thus the study design did not provide time to denture wearers for their neuromuscular mechanism to adapt to the modifications prior to testing masticatory function. A replication of this study that permits sufficient adaptation time after each modification is suggested to validate the findings.

Veterans Administration Cooperative Dental Implant Study — Comparisons between fixed partial dentures supported by blade-vent implants and removable partial dentures. Part I: Methodology and comparisons between treatment groups at baseline

This study was conducted to determine whether fixed partial dentures supported by dental implants provide an acceptable alternative to conventional removable partial dentures in patients with Kennedy class I or class II edentulous conditions. The acceptability of the new treatment will be based on success rates, impact on the health of the remaining dentition, masticatory performance, patient satisfaction, and maintenance care and cost. The study was planned also to provide comparisons between two designs commonly used by dentists for fabricating removable partial dentures. The designs differed only in terms of the type of the retainer (clasp type) and tooth support (rest location). A total of 272 patients with Kennedy class I and class II edentulous conditions were assigned on a random basis to one of the treatment groups, 134 to receive a removable partial denture and 138 a fixed partial denture supported by a blade-vent implant. All of the patients were medically screened and met prespecified criteria for oral hygiene, bone support for abutment teeth, and size of the residual ridge. Thirty-four patients were eliminated from the study before completion of their treatment. An additional six patients with early implant failures were reentered in the study and followed up as a separate group. The remaining 232 patients received comprehensive dental care, including removable partial dentures for 118 and fixed partial dentures for 114 patients. A series of examinations, radiographs, masticatory performance tests, patient satisfaction, food selection questionnaires, and dietary history were completed before initiation of the treatment, 16 weeks after the insertion of an RPD or an implant, and thereafter at 6-, 18-, 36-, and 60-month intervals. In addition, patients were seen at 6-month intervals for a recall dental examination, oral prophylaxis, plaque instructions, radiographic survey of the implant, and any needed dental treatment. The randomization stratification approach produced two treatment groups with comparable age, number of remaining maxillary and mandibular teeth, type of opposing dentition, and percent of patients with Kennedy class I and class II edentulous conditions. The mean scores of bone support, tooth mobility, and sulcular depths of abutment teeth were also similar. Significant but comparable improvements in oral hygiene and sulcular depth occurred in the two groups after treatment. The periodontal health scores at the 16-week interval serve as the baseline to measure subsequent changes in periodontal health.(ABSTRACT TRUNCATED AT 400 WORDS)

Relationship of parotid saliva flow rate and composition with personality traits in healthy men

A number of studies have investigated the relationship between parotid saliva flow rate and clinical depression. However, no comprehensive study of the intercorrelations between parotid gland secretion and normal personality traits has been reported. The stimulated flow rate, pH, osmolality, and eleven composition variables were measured in 390 normal men and correlated against eight personality dimensions derived from scores obtained from the Cattell Sixteen Personality Factor questionnaire (16PF) and a modified form of the Eysenck Personality Inventory. Flow rate, pH, osmolality, and eight of the eleven salivary components were significantly correlated with four personality traits: anxiety, conscientiousness, shrewsness, and introversion. The relationship of personality traits to the parotid gland flow rate and saliva composition is discussed in terms of both physiologic models and the possible mediating effect by the sympathetic and parasympathetic nervous systems.

Longitudinal Age-related Changes in Human Parotid Saliva Composition

For the most part, our current understanding of age-related changes in parotid saliva composition is derived from information obtained in cross-sectional studies (Baum, 1981; Baum et al., 1982; Chauncey et al., 1980; Dawes, 1969, 1970; Podorozhnaya, 1963; Shannon, 1973). In addition, many studies have been undertaken in an effort both to elucidate normal glandular activity and to evaluate changes associated with systemic diseases (Ben-Aryeh and Gutman, 1981; Forland et al., 1964; Wotman et al., 1967). Thus, there is a large reservoir of literature relating to human parotid gland function in both healthy and diseased states, yet relatively little information exists concerning longitudinal age-related composition changes in normal healthy adults. The present study was undertaken to determine cross-sectional and longitudinal age-related changes in parotid saliva flow rate and composition in normal persons.

Effect of denture base thermal conductivity on gustatory response

Abstract The effects of thermal conductivity of metal and acrylic resin palatal bases on gustatory response was compared in 10 subjects. Two similar maxillary palatal bases, one in metal and the other in acrylic resin, were fabricated for each subject. Each palatal base contained a chamber which permitted circulation of water at prespecified temperatures. The superior conductivity of the metal over the acrylic resin base was evident by the higher palatal tissue temperatures with hot stimulus and lower temperatures with cold stimulus. The parotid response varied with the concentration and type of taste stimulus, but did not show any enhancement of sweet or acid stimuli either at hot or cold palatal tissue temperatures under the metal palatal base. Instead, increased, sustained higher palatal tissue temperature under the metal base seemed to interfere more with the gustatory response to taste stimuli than the acrylic resin base.

Replicability of electromyographic recordinds of the masseter muscle during mastication

This study evaluates the reliability of a method to duplicate the location of surface electrodes for recording the electromyographic activity of masseter muscles during mastication and quantifying the activity by a microcomputer system. A plastic framework consisting of a bite fork and electrode positioners was used to place the electrodes by relating the positioners to an occlusal index and keeping this relationship constant at subsequent sittings. EMG recordings were repeated on two different days for each of 10 subjects while they performed standardized masticatory performance tests with peanuts and carrots. The muscle activity recorded with hardware integrators was an average of 26.7% of the computerized software integrations but measures derived from the two methods of integration were highly correlated (r = 0.965) and yielded similar results. Significant correlations were found between test sessions for each measure of masticatory performance and integrated EMG activity for ipsilateral and contralateral muscles. For each subject, no significant differences were found between sessions for any masticatory performance or EMG variable. The results indicate that reliable inter session EMG recordings during mastication can be made by using the template for positioning of the electrodes. In addition, the microcomputer data acquisition system provides results comparable to those obtained with conventional hardware integrators, with the added benefit of providing information on each individual stroke and its various components.

A cephalometric study of mandibular cortical bone thickness in dentulous persons and denture wearers

Cephalometric measurements of the cortical thickness of the inferior mandibular border and the inferior aspect of the mandibular symphysis were compared in two groups of subjects, one with complete dentition and the other wearing complete maxillary and mandibular dentures. Although the cortical thickness of the inferior mandibular border increased slightly with age in both dentition groups, the cortical thickness was significantly less in denture groups than in their respective dentition groups. The opposite was true with the cortical thickness of the inferior aspect of the mandibular symphysis; a decrease in thickness was noted with age, and a slight increase in thickness was noted with edentulousness. The results suggest that bone remodeling can be expected at sites distant from the residual ridge in denture wearers.