Swallowing threshold parameters of subjects with shortened dental arches.

OBJECTIVES: To quantify swallowing threshold parameters of subjects with a moderate shortened dental arch dentition (SDA: missing molar teeth, but premolar teeth in occluding position and uninterrupted anterior regions) compared to subjects with a complete dental arch dentition (CDA). METHODS: Fourteen females with SDA (3-4 occlusal premolar units) and 14 females with CDA were instructed to chew silicone test 'food' (cubic particles with a total volume of 3 cm(3)). They spit it out the moment they felt the urge to swallow and the pulverized particles were collected. Swallowing threshold parameters were number of chewing cycles, time until 'swallowing', and median particle size of the pulverized particles as determined by sieving the food. Chewing tests were performed twice and outcomes were averaged. RESULTS: The number of chewing cycles until 'swallowing' of subjects with SDA was approximately 1.7 times (p<0.005) that of the controls and this took approximately 1.6 times more time (p<0.01). The median particle size until 'swallowing' did not differ significantly between the groups, but demonstrated large individual differences. Regression analyses indicated that the ratio of median particle size until 'swallowing' of SDA and CDA becomes progressively unfavourable for SDA with increasing numbers of chewing cycles. CONCLUSIONS: Subjects with SDA pulverized test 'food' particles to sizes comparable to subjects with CDA, but chewed longer with more chewing cycles until 'swallowing'. Higher numbers of chewing cycles were associated with increasing difference between SDA and CDA regarding the median particle size until 'swallowing'. CLINICAL SIGNIFICANCE: Compared to subjects with CDA, subjects with moderate SDA pulverize test food particles to comparable size by chewing longer before "swallowing". Therefore, overloading the digestive system by swallowing courser food particles is unlikely in SDA. Consequently, replacement of absent molars just to optimize chewing function is not advised.

Comparing masticatory performance and mixing ability.

Masticatory performance has often been measured by determining an individual's capacity to comminute a test food. Another method to determine masticatory performance, which is now widely used, evaluates the ability to mix and knead a food bolus. Two-coloured chewing gum and paraffin wax have been used as test foods for the quantification of the mixing ability. The aim of our study was to compare the results obtained with the comminution of an artificial test food and the results obtained from mixing of a two-coloured chewing gum. The degree of mixing of the colours of the chewing gum was quantified with an optical method. Twenty young subjects with a natural dentition (average age 24 years) and twenty elderly subjects, mostly with complete dentures (average age 72 years), participated in the study. Significant differences in masticatory performance between the two groups were detected with both methods. However, the comminution test was better in discriminating the masticatory performance of the two groups. The mixing ability test with the two-coloured chewing gum proofed to be a good method to determine masticatory function in subjects with a compromised masticatory performance (elderly subjects). However, the method appeared to be less suitable for subjects with a good masticatory performance (young subjects).

Swallowing threshold and masticatory performance in dentate adults.

A variety of both natural and artificial foods are commonly used for the evaluation of masticatory function. We compared swallowing thresholds of three natural foods (peanuts, cheese and carrots) to those of a standardized artificial test food (Optocal Plus) and examined the relationship between masticatory performance and the swallowing threshold. Eighty-seven healthy dentate subjects participated (25 men and 62 women, aged 42.0+/-12.1 years). We evaluated the dental state, registered the number of chewing strokes used before swallowing, analyzed the chewed particles and determined median particle sizes (X50) for Optocal Plus after 15 chewing strokes and at the moment of swallowing. The results show that the number of strokes used before swallowing each natural food linearly increased with volume (P<0.001), and that carrots required more strokes than peanuts and cheese (P<0.001). The number of chewing strokes used before swallowing Optocal Plus was comparable to the number used for carrots. Masticatory performance was significantly influenced by dental state, but not by age or gender. Significant correlations were observed for: (1) the number of chewing strokes used before swallowing natural foods and Optocal Plus; (2) the median particle sizes after 15 strokes and before swallowing; (3) the number of chewing strokes before swallowing and the corresponding median particle size. However, median particle sizes as obtained after 15 strokes did not correlate with the number of strokes used before swallowing (r=0.02). Thus, bad chewers did not necessarily chew longer before swallowing than good chewers. As a consequence bad chewers would, on average, swallow larger food particles.

Masticatory function with implant-supported overdentures.

The type of attachment that is used in implant-supported mandibular overdentures may influence the retention and stability of the prosthesis and, thus, masticatory function. In this within-subject cross-over clinical trial, we examined the hypothesis that greater retention and stability of the overdenture improve the masticatory function. Eighteen edentulous subjects received 2 oral implants, a new overdenture, and, successively, 3 different suprastructure modalities: magnet, ball, and bar-clip. Masticatory performance, masticatory efficiency, and swallowing threshold were measured. The masticatory function significantly improved after implant treatment with each of the 3 attachments. We observed small differences in masticatory function among the 3 attachment types: slightly better masticatory performance with ball and bar-clip than with magnet attachments. The number of chewing cycles until swallowing hardly decreased after implant treatment. We conclude that significantly better masticatory performance, combined with a slightly smaller number of chewing cycles after implant treatment, results in smaller food particles being swallowed.

Comparison of single and multiple sieve methods for the determination of masticatory performance.

In the majority of studies on masticatory performance, the degree of food breakdown has been determined by sieving the food with one or more sieves. The aim of the present study was to compare the results obtained with a single and a multiple sieve method, as these methods have never been compared. We analysed the chewed food of 176 dentate subjects with a single and a multiple sieve method. Furthermore, we quantified the influence of age, gender, and dental status on the masticatory performance in order to compare the sensitivity of both methods. We observed a significant influence of the number of occlusal units on the masticatory performance for both methods. The single sieve method is less reliable than the multiple sieve method if the sieve diameter is not close enough to the median particle size of the chewed food. Therefore, we recommend the multiple sieve method.

Comparison of single and multiple sieve methods for the determination of masticatory performance.

In the majority of studies on masticatory performance, the degree of food breakdown has been determined by sieving the food with one or more sieves. The aim of the present study was to compare the results obtained with a single and a multiple sieve method, as these methods have never been compared. We analysed the chewed food of 176 dentate subjects with a single and a multiple sieve method. Furthermore, we quantified the influence of age, gender, and dental status on the masticatory performance in order to compare the sensitivity of both methods. We observed a significant influence of the number of occlusal units on the masticatory performance for both methods. The single sieve method is less reliable than the multiple sieve method if the sieve diameter is not close enough to the median particle size of the chewed food. Therefore, we recommend the multiple sieve method.

Pain and instability during biting with mandibular implant-retained overdentures.

We tested in a randomized controlled clinical trial the effect of pain and instability of dentures on bite force with different degrees of mucosal support. The trial involved 3 groups who had received: 1) a new conventional denture (CD-group), 2) an implant-mucosa-borne overdenture on 2 IMZ implants (IMZ-group) or 3) a mainly implant-borne overdenture retained by a transmandibular implant (TMI-group). Fifty-three women and 15 men, mean age 59 years, participated in this study. Bite force measurements were made unilaterally with a transducer and bilaterally with a bite fork. After the measurements, subjects were asked whether or not biting had caused pain or tilting of one of the dentures. Significantly more complete-denture wearers reported pain. They reported more frequent pain in the mandible than in the maxilla (P < 0.001), whereas implant-groups seemed to experience more often pain in the maxilla. On the transducer, maxillary dentures of the CD-group tilted less (P < 0.01) and mandibular dentures more (P < 0.05) compared to the implant-groups. With the bite fork, tilting occurred more often in the incisal-cuspid area than in the molar region (P < 0.001). No effect of pain and tilting was observed on maximum bite force. It appears that oral implants used to stabilize mandibular dentures permit subjects to exert higher bite forces and reduce the pain as otherwise felt in the mandible during maximum biting. Due to this stabilization, pain and instability of the maxillary denture can become the limiting factor for a further increase in bite force.

Biting and chewing in overdentures, full dentures, and natural dentitions.

It has been suggested that the provision of dental implants can improve the oral function of subjects with severely resorbed mandibles, possibly restoring function to the level experienced by satisfied wearers of conventional complete dentures. Nevertheless, a quantitative comparison has never been made and can be drawn from the literature only with difficulty, since studies differ greatly in methodology. To make such a comparison, we measured bite force and chewing efficiency by using identical methods in subjects with overdentures, complete full dentures, and natural dentitions. Our results indicated that bite forces achieved with overdentures on dental implants were between those achieved with artificial and natural dentitions. Chewing efficiency was significantly greater than that of subjects with full dentures (low mandible), but was still lower than that of subjects with full dentures (high mandible) and overdentures on bare roots. Differences in the height of the mandible revealed significant differences in chewing efficiency between the two full-denture groups. Furthermore, subjects with a shortened dental arch exerted bite forces similar to those of subjects with a complete-natural dentition, but their chewing efficiency was limited due to the reduced occlusal area. For all groups combined, a significant correlation was found between maximum bite force and chewing efficiency. Nearly half of the variation in chewing efficiency was explained by bite force alone.

Bite forces with mandibular implant-retained overdentures.

Sensitivity or pain of the mucoperiosteum covering the mandibular edentulous ridge is often thought to limit bite forces in complete-denture wearers. Therefore, bite forces with mandibular implant-retained overdentures may depend on the degree of implant support. This study analyzed the effects of different degrees of support for the mandibular denture on bite forces measured four years after denture treatment as part of a randomized controlled clinical trial. All subjects had received new maxillary dentures and (1) mainly implant-borne overdentures on a transmandibular implant (TMI), (2) mucosa-borne overdentures on two cylindric permucosal IMZ implants, or (3) new conventional dentures in the mandible. Fifty-three women and 15 men (mean age, 59.1 yrs; range, 41 to 77) participated in this trial. Both unilateral and bilateral bite forces were recorded at different positions with a miniature strain gauge transducer and a mechanical bite fork, respectively. The subjects were asked to bite at three force levels. Results indicated that women had significantly lower maximum bite forces than men. Persons with mandibular implant-retained overdentures had significantly higher unilateral and bilateral maximum bite forces than complete-denture wearers. However, bite forces did not differ between the mainly implant-borne (TMI) and mucosa-implant-borne (IMZ) implant systems. Therefore, it appears that differences in support for the mandibular overdenture by dental implants are not reflected in bite force capabilities.

The state of dentition in relation to nutrition in elderly Europeans in the SENECA Study of 1993.

OBJECTIVE: To analyse the state of dentition and related aspects and to study their influence on the dietary intake of nutrients. DESIGN AND SUBJECTS: In the second cross-sectional measurement of SENECA's follow-up study, 12 research towns in 10 European countries and one town in Connecticut (USA) participated, involving 1424 elderly men and women born between 1913 and 1918. Dentition-related data were obtained from a general questionnaire; nutritional data were collected using a standardized modified dietary history. RESULTS: A large variation in the dental state existed among the towns. Women were more often edentulous and had fewer teeth. Self-reported chewing difficulties varied enormously. Most complaints were found in: women, edentulous subjects without dentures and in the towns in Spain, Portugal and Poland. More dentate women reported having visited their dentist. In the edentulous groups, differences between towns were small; for the dentate groups the percentage of dental visits varied from 0 in Coimbra (Portugal) to 96 in Mansfield (Connecticut/USA). For the edentulous subjects without any prosthetic supply, intakes of carbohydrate and vitamin B6 were significantly reduced. Also intakes of vitamin B1, vitamin C, dietary fibre, calcium and iron tended to be lower in this group. Town-dentition interactions existed for most nutrients. CONCLUSIONS: Substantial differences existed between towns in the influence of dentition on dietary intake.

[Chewing with shortened dental arches]. / Kauwen met een verkorte tandboog.

Masticatory performance as measured with (objective) chewing tests is correlated with the number of teeth (the food platform area). In general, however, the masticatory ability (the subjective chewing experience) is sufficient as long as 20 or more 'well-distributed' teeth remain, such as is the case with an SDA, when the anterior teeth and the premolar teeth are present. Research indicates that an SDA does not lead to altered food selection. Studies have shown that a free-end removable partial denture generally does not improve the oral function in terms of masticatory ability or chewing comfort, unless in case of extreme shortened dental arches with only the anterior teeth present.

[Masticatory performance with mandibular implant-retained overdentures]. / Het kauwvermogen met onderprothesen op implantaten.

It was investigated in a clinical trial whether the masticatory performance of complete-denture wearers depended on the support for their mandibular dentures by implants or mucosa. The trial involved the provision of a new maxillary denture and either a new conventional mandibular denture (mucosa-borne), a mandibular overdenture retained by two IMZ-implants (implant-mucosa-borne), or a mandibular overdenture on a transmandibular implant (TMI; mainly implant-borne). In comparison with mandibular implant-retained overdentures, subjects with conventional dentures needed 1.5 to 3.6 times more chewing strokes for an equivalent reduction in particle size. No differences in masticatory performance were found between subjects with IMZ-implants and those with TMI. This suggests that the increased stability of the mandibular denture with implants determines the wearer's masticatory performance, rather than the support by implants.