Signs and symptoms related to temporomandibular disorders--Follow-up of subjects with shortened and complete dental arches

OBJECTIVE: To assess prevalence of cardinal signs and symptoms related to temporomandibular disorders (TMD) in subjects with shortened dental arches and to clarify the individual course of these signs and symptoms. METHODS: In this 9-year follow-up study, subjects with shortened dental arches (n=74) were compared with subjects with complete dental arches (n=72). Of three reported symptoms (pain, noises/clicking and restricted mobility of the lower jaw), and of two clinical signs (palpated clicking of the temporomandibular joint and restricted maximal mouth opening) estimates of mean scores were calculated by a mixed model. Suggested determinants for TMD (gender, time, bruxism, chewing side preference) were investigated by covariate analyses. Subjects with complete 9-year follow-up (shortened dental arches: n=42; complete dental arches: n=41) were described more detailed by frequency distributions, Pearson correlations of signs and symptoms, and fluctuation of the symptoms. RESULTS: Covariate analyses using the mixed model revealed no significant differences between the shortened and the complete dental arch groups (p>0.05) with respect to symptoms and signs. Most prevailing effect was gender: females reported more frequently pain (p=0.05) and noises/clicking (p=0.03). Restricted mobility was significantly related with chewing side preference and bruxism habits (both: p=0.01). In both groups, subjects with complete 9-year follow-up had low prevalence of serious symptoms and signs and symptoms fluctuated without demonstrable correlation. CONCLUSION: In this 9-year follow-up, subjects with shortened dental arches had similar prevalence, severity, and fluctuation of signs and symptoms related to TMD compared to subjects with complete dental arches.     

A systematic review of prosthetic restoration in patients with shortened dental arches

The literature regarding the effect of prosthetic restoration in patients having distal extension edentulous space in posterior area (shortened dental arch: SDA) is reviewed in the following article. Information retrieval followed a systematic approach using PubMed. Articles in English published between 1966 and March 2011 describing the outcome of treatment with various prostheses were evaluated. From the search results of 98 articles, 21 articles met the inclusion criteria. Treatment with removable partial dentures (RPDs) improved masticatory function, patient satisfaction and oral health-related quality of life (OHRQoL). However, no significant difference was found in the outcomes between patients with RPDs and with cantilever fixed partial dentures (CFPDs). Caries developed more frequently after treatment with RPDs than CFPDs. The time to survival for CFPDs was not longer than that for RPDs, while more visits to maintain RPDs were required than for CFPDs. No significant difference was found in masticatory function, OHRQoL, and occlusal stability between patients with RPDs and those without restoration of missing molars. Consequently, treatment with RPDs for SDA seems to be less advantageous than CFPDs or no restoration for missing molars. Further research is required to validate treatment with implant-supported fixed partial dentures for SDA.     

Occlusal tooth wear in Chinese adults with shortened dental arches

To assess associations between occlusal tooth wear and shortened dental arches (SDA) in Chinese 40 years and older subjects. From a sample of 1462 urban and rural adults, those presenting with SDA (n = 150) were compared with a control group of 65 randomly selected subjects with complete dentitions (CDA). Occlusal wear was assessed using a modified Smith and Knight index – the occlusal tooth wear index (OWTI) – and analysed using multivariate (logistic) regression. There was no significant effect from SDA on severe occlusal wear (OTWI score 3 or 4: OR = 2·016; 95% CI = 0·960–4·231; P = 0·064). Higher age was associated with severe occlusal wear (P values ≤0·007) and with higher mean OTWI scores; urban had less often severe occlusal wear than rural residents (OR = 0·519; P = 0·008). Higher mean OTWI scores were associated with rural residents, except for anterior teeth. Females had lower mean OTWI score for anterior teeth (effect = ?0·153; P = 0·030). Premolars in SDA had higher mean OTWI scores compared with those in CDA (effect = +0·213; P = 0·006). In SDA, more posterior occluding pairs (POPs) were associated with lower mean OTWI sores for anterior teeth (effect: ?0·158; P = 0·008) and higher scores for molars (effect: +0·249, P = 0·003). Subjects with SDA or CDA presented comparable occlusal wear, but premolars in SDA tend to have higher probability for having occlusal wear. Fewer numbers of POPs were associated with more wear in anterior teeth.     

Chewing ability of subjects with shortened dental arches

Abstract – Objectives: The objective was to study chewing ability in subjects with shortened dental arches in Tanzania. Methods: A sample of 725 adults with shortened dental arches comprising intact anterior regions and 0–8 occluding pairs of posterior teeth and 125 adults with complete dental arches were recruited. Subjects were classified into nine categories according to arch length and symmetry. Chewing ability was investigated by interview on chewing complaints and on perceived difficulty of chewing 20 common Tanzanian foods, 12 soft, and 8 hard. Results: Categories with extreme shortened arches (0–2 pairs of occluding premolars) reported most frequent (95–98%) and most severe complaints (‘cannot chew all foods’ or ‘have to use special or specially prepared food’). Categories with intact premolar regions and at least one occluding pair of molars had nearly no complaints (95–97%). The other arch categories had an intermediate volume of complaints (33–54%). Perceived difficulty of chewing deteriorated with a decrease of occluding pairs of teeth. Subjects with 0–2 pairs of occluding premolars had major difficulties with chewing. Subjects with 3–4 pairs of occluding premolars or asymmetric arches comprising a short side with none or one pair of premolars and a long side including at least one occluding pair of molars had more difficulties with chewing compared to subjects with more complete dental arches. As a whole, they perceived for hard foods, ‘minor problems, not adapted’. Conclusions: Shortened dental arches with intact premolar regions and at least one occluding pair of molars provide sufficient chewing ability. Shortened arches with 3–4 pairs of occluding premolars and asymmetric arches with a long side result in impairment of chewing ability, especially for hard foods. In extremely shortened arches comprising 0–2 occluding premolars, chewing ability is severely impaired.     

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 cm³). 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.     

Impact of shortened dental arches on oral health‐related quality of life

This study described the prevalence of adults with shortened dental arches (SDA) in Brazil, specifically assessing the differences of oral health‐related quality of life [the prevalence and severity of oral impacts on daily performance (OIDP)] by dentition status. We analysed data from the 2010 National Survey of Oral Health in Brazil, including home interviews and oral examinations. The assessment of SDA used two alternative definitions: having 3–5 natural occlusal units (OUs) in posterior teeth or having 4 OUs in posterior teeth. Both definitions included having intact anterior region and no dental prosthesis. The analysis was weighted, and a complex sampling design was used. Negative binomial regression models assessed associations as adjusted for socio‐demographic conditions and dental outcomes. A total of 9779 adults (35–44 years old) participated in the study. A non‐negligible proportion had SDA: 9·9% and 3·8% for the first and second definition, respectively. Individuals with SDA (first definition) ranked higher in OIDP prevalence [count ratio (CR) 1·22; 1·09–1·36, 95% confidence interval (CI)] and severity (CR = 1·43; 1·19–1·72, 95% CI) than those with more natural teeth. This difference was not statistically significant when adjusted for socio‐demographic and dental covariates: OIDP prevalence (CR = 1·04; 0·92–1·17, 95% CI) and severity (CR = 1·09; 0·91–1·30, 95% CI). Analogous results were obtained when the second definition of SDA was adopted. These findings suggest that a considerable contingent of adults may function well without dental prostheses, despite having several missing teeth. This conclusion challenges the traditional approach of replacing any missing tooth and instructs the allocation of more dental resources to preventive, diagnostic and restorative services.     

Factors related to prosthetic restoration in patients with shortened dental arches: a multicentre study

The aim of this study was to identify the factors related to prosthetic restoration in patients with shortened dental arches (SDA). SDA patients with 2-12 missing occlusal units were consecutively enrolled from seven university-based dental hospitals in Japan. Of the 145 subjects (mean age; 63·4 years), 41% chose no treatment and 59% sought to replace their edentulous spaces with removable partial dentures or implant-supported fixed partial dentures. Restoration decisions were related to tooth loss patterns. Only 3% of subjects missing just second molar(s) sought to receive prosthetic treatment, while the percentage increased to 58% in subjects who were missing first and second molars and 93% in subjects missing premolar(s). Logistic regression analyses found that young age, increased number of missing occlusal units, asymmetric arch and presence of chewing complaint were significant predictors for prosthetic restoration (P<0·05). Increased number of missing occlusal units and asymmetric arch were significant predictors for the presence of chewing complaint (P<0·05). These results suggest that perceived impairment of chewing ability owing to missing occlusal units is a critical factor for prosthetic restoration in SDA patients.     

Effect of implant‐supported prosthesis on the bite force and masticatory efficiency in subjects with shortened dental arches

The aim of the study was to assess changes in bite force and masticatory efficiency in shortened dental arch (SDA) subjects rehabilitated with implant‐supported restoration for 1st molar. Ten SDA subjects with bilaterally missing mandibular molars (experimental group) were recruited. In each subject, one tapered threaded implant was placed bilaterally in 1st mandibular molar region and restored. Masticatory efficiency was evaluated objectively by measuring the released dye from chewed raw carrots, with a ‘spectrophotometer’ at 530 nm preoperatively and at 3 months after restoration. Bite force was evaluated using ‘bite force measuring appliance’ preoperatively, at 6 weeks and at 3 months after restoration. Ten completely dentate‐matched subjects (in terms of age, sex, height and weight) acted as control. The results revealed that as compared with the control group, the experimental group showed significantly less (P < 0·05) mean maximum bite force at pre‐restoration and at 6 weeks after restoration. Although at 3 months the mean maximum bite force value was less than the control group but the mean difference was statistically insignificant. The mean difference of masticatory efficiency between control and experimental group was statistically significant (P < 0·05) before restoration, but was statistically insignificant at 3 months after restoration. Thus it was concluded that after the restoration of mandibular arch with implant‐supported prosthesis, both bite force and masticatory efficiency of all SDA subjects increased and were comparable to that of matched completely dentate subjects after 3 months.     

Management of shortened dental arches and periodontal health: 5‐year results of a randomised trial

In a multicentre randomised trial (German Research Association, grants DFG WA 831/2‐1 to 2‐6, WO 677/2‐1.1 to 2‐2.1.; controlled‐trials.com ISRCTN97265367), patients with complete molar loss in one jaw received either a partial removable dental prosthesis (PRDP) with precision attachments or treatment according to the SDA concept aiming at pre‐molar occlusion. The objective of this current analysis was to evaluate the influence of different treatments on periodontal health. Linear mixed regression models were fitted to quantify the differences between the treatment groups. The assessment at 5 years encompassed 59 patients (PRDP group) and 46 patients (SDA group). For the distal measuring sites of the posterior‐most teeth of the study jaw, significant differences were found for the plaque index according to Silness and Löe, vertical clinical attachment loss (CAL‐V), probing pocket depth (PPD) and bleeding on probing. These differences were small and showed a slightly more unfavourable course in the PRDP group. With CAL‐V and PPD, significant differences were also found for the study jaw as a whole. For CAL‐V, the estimated group differences over 5 years amounted to 0·27 mm (95% CI 0·05; 0·48; P = 0·016) for the study jaw and 0·25 mm (95% CI 0·05; 0·45; P = 0·014) for the distal sites of the posterior‐most teeth. The respective values for PPD were 0·22 mm (95% CI 0·03; 0·41; P = 0·023) and 0·32 mm (95% CI 0·13; 0·5; P = 0·001). It can be concluded that even in a well‐maintained patient group statistically significant although minor detrimental effects of PRDPs on periodontal health are measurable.     

Observational study investigating tooth extraction and the shortened dental arch approach

The shortened dental arch (SDA) provides a cost‐effective dentition, considering the population is ageing and retaining teeth for longer. The aims were to observe the reasons and sites of tooth extraction and assess the functional dentition over 15 years in dental practice. Subjects were recruited who required permanent tooth extractions between 2000 and 2015. The reasons for extractions were chosen from twelve extraction codes. Data were also collected for demographics, tooth position, root treated teeth and functional pairs remaining. Patient‐centred factors on reasons for tooth extraction and comments on chewing ability and aesthetics following extractions were recorded. Nine hundred and fifty‐one teeth were extracted in 900 patients. The mean age was 60 years (SD 20, SE 7, 95% CI 46, 74). Reasons for extraction were periodontal disease (n = 361, 38%), periapical infection (n = 288, 34%) or tooth and tooth‐root fractures (15%). Extractions included 201 (21%) second molars, 179 (19%) first molars, 152 (16%) second premolars, 95 (10%) first incisors, 86 (9%) second incisors, 76 (8%) canines and 67 (7%) first premolars. Following extractions, median functional pairs were 12, interquartile range (IQR) 19–7. Individuals with ≥10 functional pairs including anterior teeth (60%, n = 571) had no complaints with chewing ability or aesthetics. They did not require additional prostheses. Periodontal disease and periapical infection were the main causes for the extraction. First and second molars followed by second premolars were the most commonly extracted teeth. This study supports the SDA in creating a cost effective, functional dentition in an aging population, provided remaining teeth and restorations are preserved/maintained, oral health is promoted, and anterior aesthetic tooth replacement is ensured.     

Efficacy of a posterior implant support for extra shortened dental arches: a biomechanical model analysis

The purpose of this study was to test the efficacy of utilizing implants underneath distal free-end denture bases to establish a stable occlusal support for extreme shortened dental arches (ESDA). The authors constructed a two-dimensional finite element model of the ESDA where only lower anterior teeth remain. Posterior occlusal support was provided by a fixed partial denture with an osseointegrated implant (IFPD), fixed cantilever partial denture (CFPD), or a removable partial denture with or without an implant underneath (IRPD and RPD). A dentate mandible model was the control. When muscle vectors simulating clenching force were applied, stress levels on the temporal bone surface area under each configuration were compared, to evaluate the efficacy in establishing the occlusal support. The largest stress increase in temporal bone was found in the ESDA situation followed by the RPD. The least amount of stress increase was found with the IFPD followed by IRPD when the implant was placed in the molar region. The stress increase with IRPD was about 20-45% of the amount with RPD. Our results suggest that IFPD provides most favourable and stable occlusal support, however, IRPD with a single posterior implant also provide stable occlusal support with reducing the stress levels in the temporomandibular joint.     

Gastric emptying rate in subjects with experimentally shortened dental arches: a pilot study

Summary  Although a shortened dental arch has been reported to provide sufficient subjective chewing ability, the loss of molar occlusion significantly reduces trituration ability, and may result in an impaired digestive function including delayed gastric emptying. This study investigated the effect of the experimental loss of molar occlusion on gastric emptying rate. Thirteen healthy dentate males underwent two sessions of gastric emptying rate measurement after ingestion of the same test meal that contained ham, bread and an egg mixed with carbon-labelled octanoic acid. A test food was divided into nine equal portions, and each was consumed in 60 cycles of chewing. In one of the two sessions, the subjects wore an intraoral appliance devised to simulate the occlusal conditions of the shortened dental arches. Two parameters of gastric emptying; namely, the lag phase ( T _lag) and gastric half-emptying time ( T _1/2), were evaluated by means of a ¹³C-octanoic acid breath test. Following the measurement of gastric emptying in each session, masticatory performance was evaluated by a conventional sieve test. Masticatory performance decreased significantly in case of loss of molar occlusion (78·1 ± 11·1% versus 33·4 ± 18·2%, P  <0·001); however, no significant changes were observed in terms of the gastric emptying parameters ( T _lag: 99 ± 19 versus 105 ± 34 min; T _1/2: 168 ± 32 versus 178 ± 48 min). Within the limitations of this study, it was concluded that reduction in food trituration caused by shortening of the dental arch does not significantly affect gastrointestinal digestive function.     

The relationship between tooth loss and cerebral stroke

Objective

Tooth loss has been suggested as a potential risk factor for cerebral stroke. This report reviews prospective studies investigating the association between tooth loss and stroke.

Method

The PubMed database was used to identify studies about the relationship between tooth loss and stroke including prospective, cohort, and follow-up studies reported from 2000 to 2010.

Results

Four prospective follow-up studies have been conducted on the relationship between tooth loss and stroke and three of four reports have suggested that tooth loss is related to incidence of both ischemic and hemorrhagic stroke.

Conclusion

The results of this review study support the hypothesis that there is an association between early tooth loss and the occurrence of stroke.     

Wear of resin denture teeth in partial removable dental prostheses

PurposeTo investigate occlusal wear of resin denture teeth in partial removable dental prostheses worn by partially edentulous patients.MethodsThirty patients with partial removable dental prostheses were included in the study. Thirty-two patients with complete dentures served as a reference group. Occlusal wear after two years was evaluated indirectly using gypsum casts and a three-dimensional laser-scanner device. Overall wear of complete occlusal surfaces and maximum wear of occlusal contact areas were measured. Patient and prosthesis data were analyzed using univariate and multiple linear mixed models.ResultsOverall wear of denture teeth in partial removable dental prostheses was 91 (SD 85) μm, and maximum wear of occlusal contact areas was 329 (SD 204) μm (means and standard deviations). Average and maximum wear values for teeth in complete dentures were both lower than those for teeth in partial removable dental prostheses. However, differences between wear of different types of denture did not reach statistical significance after adjustment for gender, type of tooth, dental status of the opposing jaw, and antagonist material. Statistical analysis revealed that wear was greater for denture teeth occluding with ceramic crowns and/or fixed partial dentures as antagonists.ConclusionsResin denture teeth in partial removable and complete dental prostheses are subjected to clinically important occlusal wear that might destabilize occlusion and cause further problems. Patient-related factors and dental status affect wear behavior and should be taken into consideration when treating patients with removable dentures.     

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.