Mandibular residual ridge morphology in relation to complete dentures and implant overdentures-Part I: Predictors for perceived conventional denture stability.

BACKGROUND: There is lack of reliable predictors for success of conventional complete denture (CCD) therapy, which in turn might affect the effectiveness of subsequent implant-retained overdenture (IOD) therapy. PURPOSE: To investigate relationships between digitally obtained geometrical mandibular residual ridge measures and perceived CCD-stability. MATERIALS AND METHODS: 30 CCD wearing patients (67.9 ± 7.0 years) for whom a new set of CCDs was advised, were treated with new CCDs. Digitalized mandibular gypsum models were measured using the Geomagic Studio 2013 software. Data were obtained for (1) height, width, and cross-section surface area of the residual ridge at different locations (midline, premolar, and anterior edge of retromolar pad) and (2) denture base surface area. Scatter plots and multivariate regression analyses were used to investigate associations between the geometric data and denture base surface area, and correlated with denture stability scores (Spearman rank test). RESULTS: Scatter plots showed that best model fit for denture base surface area was mean ridge height (R2 = 0.906). Multivariate regression showed that height at premolar location (p = 0.001) had largest effect on denture base surface area (R2 = 0.796). Ridge morphology variables, except width at midline location, were significantly correlated with CCD-stability (p-values <0.05). CCD-stability was significantly correlated with denture base surface area (p ≤ 0.001). CONCLUSION: Residual ridge height at premolar location was most predictive for denture base surface area and perceived CCD-stability.

Mandibular residual ridge morphology in relation to complete dentures and implant overdentures-Part II: Predictors for effectiveness of implant overdenture therapy.

BACKGROUND: The significance of mandibular residual ridge height and satisfaction with conventional complete dentures (CCD) as predictors for the added value of implant-overdenture (IOD) therapy is unknown. PURPOSE: To investigate the predictive value of thresholds for (1) residual ridge height at premolar location (PRH), and (2) satisfaction with CCD-stability for the added value of two intraforaminal implants supporting the mandibular CCD. METHODS: Thirty CCD wearing patients (67.9 ± 7.0 years) for whom a new CCD was advised, received a new CCD. Mandibular gypsum models were digitally measured. After 3 months free of complaints (T1), perceived CCD-stability was evaluated, and participants received two intraforaminal implants. At T1 and T2 (3 months free of complaints after IOD therapy) participants completed OHIP14-CN, and denture satisfaction (VAS) questionnaires, and performed mixing ability tests. Participants were grouped according to PRH of ≥6.15 mm versus < 6.15 mm, and perceived CCD-stability satisfied vs. dissatisfied. Scores at T2 were compared to T1 (paired t-tests). Predictive values of PRH and CCD-stability were analyzed with logistic multivariate regression models. RESULTS: At T2, only participants with PRH of <6.15 mm or dissatisfied with CCD-stability had significant lower OHIP-total and domain scores for 'physical pain' and 'physical disability' and significantly higher VAS scores for perceived chewing function, denture retention and oral comfort. Regression analyses showed that participants with PRH of <6.15 mm, or dissatisfied with CCD-stability had significantly higher chance for lower OHIP-total and domain scores 'physical pain' and 'physical disability', and for higher VAS scores for perceived chewing function, denture retention and oral comfort at T2. Masticatory performance improved significantly after IOD therapy, but independent of PRH and CCD-stability. CONCLUSION: PRH and satisfaction with CCD-stability were adequate prognostic indicators for improvement of oral health-related quality of life and denture satisfaction by mandibular IOD therapy.

Wish-fulfilling medicine and wish-fulfilling dentistry.

OBJECTIVES: to explain the practice of wish-fulfilling medicine and how it relates to dentistry. SOURCES: Relevant papers, and reports from authoritative institutions were identified in Pubmed and Google Scholar. RESULTS: Wish-fulfilling medicine refers to services provided by professionals using medical methods in a medical setting to address non-medical wishes of patients. Care-providers, medical industries, and health-insurance companies also contribute to wish-fulfilling in medicine and dentistry. Various concepts of health and illness compounded by blurred borders between health and illness offer an unstable foundation for wish-fulfilling medicine, and growing demands for these services where healthcare resources are limited can displace medically necessary treatments. Moreover, treatments without a medical or a dental necessity, can be harmful and bear the risk of futile or excessive treatments not in patients' long-term interest. Examples in dentistry are found in the field of cosmetic interventions, prosthodontics and orthodontics, where perceptions of small 'deviations' from normality prompt wishes or recommendations for intervention. Ethically, wish-fulfilling services confront the principles of the common morality if the autonomy of a patient is compromised, beneficence is unclear, harm is foreseeable, or distributive justice is compromised. Wish-fulfilling dental treatment can be restricted by legislation if it conflicts with safe, effective and efficient care, or if it interferes with patient's real needs or undermines established professional standards. CONCLUSIONS: The general understanding of wish-fulfilling medicine including its ethical and legal themes is relevant to dentistry. CLINICAL RELEVANCE: Ethical considerations and legislation can guide a dentist to reflect critically on clinical decisions regarding wish-fulfilling dentistry.

Food avoidance is associated with reduced dentitions and edentulousness.

OBJECTIVES: To investigate associations between food avoidance and dental status, age, gender, and socio-economic status (SES). MATERIALS AND METHODS: The Chinese sample comprised 1463 dentulous (≥ 1 tooth in each jaw) and 124 edentulous (in one or both jaws) participants aged ≥ 40 yrs. The Vietnamese sample comprised 2820 dentulous and 253 edentulous participants aged ≥ 20 yrs. Food avoidance due to chewing difficulties was scored for regionally common 4 soft and 4 hard foods. Dental status was classified according to the multi-level hierarchical dental functional classification system (HDFC) based on the number and location of teeth and posterior occlusal pairs. Associations were analyzed using multivariate logistic regression analyses. RESULTS: For dentulous participants, the chance of avoiding foods was significantly larger with < 10 teeth in each jaw (OR = 2.26 (Chinese sample), respectively 1.74 (Vietnamese sample)), incomplete anterior region (OR = 1.78, respectively 1.84), "impaired" premolar region (OR = 2.22, respectively 1.71), or "impaired" molar region (OR = 2.46, respectively 1.84). Edentulous participants had twice the chance of avoiding foods (OR = 2.01 respectively 2.20). Avoiding foods was significantly associated with higher age. Participants of low SES (Chinese sample, OR = 1.93) and females (Vietnamese sample, OR = 1.27) had a larger chance of avoiding foods. CONCLUSIONS: Avoiding foods was significantly associated with reduced dentitions, edentulousness, and higher age; low SES only in the Chinese and being female only in the Vietnamese sample. CLINICAL RELEVANCE: Incomplete anterior regions, "impaired" premolar or molar regions, and especially edentulousness can be considered significant risk indicators for food avoidance.

The relationship between masticatory ability, age, and dental and prosthodontic status in an institutionalized elderly dentate population in Qingdao, China.

OBJECTIVES: To identify relationships between masticatory ability and age, and dental and prosthodontic status amongst an institutionalized elderly dentate population in China. MATERIALS AND METHODS: A sample of 512 elders living in eight nursing homes in Qingdao was categorized based on a hierarchical dental functional classification system with and without tooth replacements. Masticatory disability scores (MDSs) were analyzed using multiple regression models with only age, and age and dentition variables for participants having ≥ 10 natural and those having < 10 natural teeth in each jaw. RESULTS: Overall, associations between MDS and age, number of teeth, and number of teeth replaced by dental prostheses were identified. For participants having ≥ 10 natural teeth in each jaw, no significant associations between MDS and age and dental and prosthodontic status were found. Participants having < 10 natural teeth in each jaw had higher MDS (increasing chewing difficulties) at higher ages. However, when "premolar region sufficient" and "molar region sufficient" were included, MDS was not associated with age, but with these dentition variables. For participants having ≥ 10 teeth including prosthodontically replaced teeth in each jaw, age was the only variable associated with MDS. For participants having < 10 teeth including teeth replaced in each jaw, the significant factor was "premolar region sufficient." Overall, lower MDS was associated with increasing number of teeth, as well as with increasing number of teeth replaced by dental prostheses. CONCLUSIONS: In this population of institutionalized dentate elderly, masticatory ability was significantly associated with dental and prosthodontic status. CLINICAL RELEVANCE: For institutionalized elderly, having less than ten natural teeth in each jaw is associated with chewing problems. Most important dentition factor is the presence of three to four premolar pairs. Teeth added by partial removable dental prostheses compensate impaired masticatory ability due to tooth loss for 50% compared to natural teeth.

Long-term follow-up indicates unimpaired oral health-related quality of life for people having shortened dental arches.

OBJECTIVES: To assess and analyse OHRQoL of people with shortened dental arches (SDA) in a long-term cohort study. METHODS: All participants of a long-term cohort study on SDA who were still attending the university dental clinic and still had an SDA (SDA group) with 3-5 posterior occluding pairs and intact anterior areas, an SDA plus removable dental prosthesis (SDA plus PRDP group) or complete dental arch (CDA group) completed the Dutch version of the Oral Health Impact Profile (OHIP-49NL) and additional questions on satisfaction with their dental status (yes/no). Mann-Whitney tests were performed for OHIP total scores and OHIP domain scores. The chance that the difference in median OHIP scores between the groups was larger than 6 OHIP units, was calculated by a bootstrapping procedure. RESULTS: 10 participants were eligible for SDA group and 11 for CDA group. The SDA plus PRDP group (n=1) was excluded from analyses. Mean follow-up period was 29.3±5.5 for SDA group and 36.7±5.5years for CDA group. Mean OHIP-49NL score was 13.9±10.9 for SDA group and 11.3±8.6 for CDA group. Differences in mean total scores and mean scores per domain were not statistically different. The probability that a difference in median OHIP total scores between groups was larger than 6 OHIP units was 0.25. Both groups showed high percentages of satisfaction with dental condition, except for dental appearance. CONCLUSION: OHRQoL of people with a long-term SDA condition was similar to that of people with CDA. CLINICAL SIGNIFICANCE: People having SDA for long periods are expected to report similar OHRQoL and satisfaction levels/oral comfort as people with CDA.

Oral health care behavior and frailty-related factors in a care-dependent older population.

OBJECTIVES: To assess, in older people with different levels of care-dependency 1) which frailty- and non-frailty related predisposing, enabling and need factors are associated with a) dental service use (DSU) frequency, b) changed DSU after the onset of care-dependency, c) brushing frequency, and d) changed brushing frequency since the onset of care-dependency; and 2) if unfavorable oral health care behavior is related to unfavorable oral health outcomes. METHODS: Bivariate analyses and multivariable logistic regression analyses were performed to evaluate data from 126 Dutch care-dependent people aged≥65 on oral and general health, psychological and social issues. RESULTS: Lower DSU frequency was mainly related to non-frailty-related predisposing factors, especially being edentate (OR=3.75; CI: 1.20-11.71; p=0.023) and lower socioeconomic status (OR=1.74; CI: 0.97-3.14; p=0.065); lower DSU frequency since the onset of care-dependency to frailty-related enabling and need factors, especially 'difficulty going to the dentist' (OR=4.98; CI:1.85-13.36; p=0.001) and clinically assessed treatment need (OR=3.23; CI:1.24-8.42; p=0.016); lower brushing and changed (reduced) brushing frequency to frailty-related enabling factors, and, in case of reduced frequency, significantly to 'not being capable of summoning the effort to brush' (OR=8.28; CI: 1.44-47.56; p=0.018) and high care-dependency level (OR=4.14; CI: 1.05-16.36; p=0.043). Elders with lower and especially those with reduced DSU and brushing frequencies since the onset of care-dependency, had generally worse oral health outcomes and related quality of life. CONCLUSIONS: Oral health care behavior, especially lower brushing and DSU frequency since the onset of care-dependency, is related to specific frailty-related factors in a care-dependent older population. CLINICAL SIGNIFICANCE: Oral care-providers should be alert to the role of specific frailty-related factors, which are likely to reduce DSU and brushing frequency in the course of increasing frailty.

Invited Commentary: Shortened Dental Arch Research Conclusions for Edentulous Patient Management.

No abstract available.

Clinical Fit of Partial Removable Dental Prostheses Based on Alginate or Polyvinyl Siloxane Impressions.

PURPOSE: The aim of this study was to analyze the clinical fit of metal-frame partial removable dental prostheses (PRDPs) based on custom trays used with alginate or polyvinyl siloxane impression material. MATERIALS AND METHODS: Fifth-year students of the Nijmegen Dental School made 25 correct impressions for 23 PRDPs for 21 patients using alginate, and 31 correct impressions for 30 PRDPs for 28 patients using polyvinyl siloxane. Clinical fit of the framework as a whole and of each retainer separately were evaluated by calibrated supervisors during framework try-in before (first evaluation) and after (second evaluation) possible adjustments (score 0 = poor fit, up to score 3 = good fit). Framework fit and fit of the denture base were evaluated at delivery (third evaluation). Finally, postinsertion sessions were evaluated and total number of sessions needed, sore spots, adjustments to the denture base, and reported food-impaction were recorded. RESULTS: No significant differences in clinical fit (of the framework as a whole, for the retainers, or for the denture base) were found between the groups in the three evaluation sessions. Differences were not found for postinsertion sessions with one exception: in the alginate group, four subjects reported food impaction, versus none in the polyvinyl siloxane group. CONCLUSION: Clinical fit of metal-frame PRDPs based on impressions with custom trays combined with alginate or polyvinyl siloxane was similar.

Missing Teeth and Prosthodontic Replacement in an Institutionalized Dentate Population of 60 Years and Older in Qingdao, China.

PURPOSE: The aim of this study was to investigate missing teeth and prosthodontic replacements in an institutionalized elderly population in China, and to assess dental functionality before and after the prosthodontic replacements based on a hierarchical dental functional classification (HDFC) system. MATERIALS AND METHODS: A sample of 512 participants (9% aged 60-69 years; 29% aged 70-79 years; 62% aged ≥ 80 years) living in eight nursing homes in Qingdao were categorized by the HDFC with and without tooth replacements. A functional dentition in the HDFC meets all the following criteria: ≥ 10 natural teeth in each jaw; a complete anterior region; 3 or 4 posterior occluding pairs (POPs) in the premolar regions; and ≥ 1 POP bilaterally in the molar region. Participants with tooth replacements were reclassified. The score for effectiveness of replacements were as follows: 4 for ≥ 10 teeth in each jaw; 3 for a complete anterior region; 2 for 3 or 4 POPs in premolar regions; and 1 for ≥ 1 molar POP bilaterally. RESULTS: Twenty percent of the participants had functional dentitions, but 42% met none of the functional criteria. In the branch '≥ 10 teeth in each jaw' the mean number of teeth present was 26.3 ± 2.9, and the mean number of POPs was 6.2 ± 2.0. In the branch '< 10 teeth in each jaw,' there were 13.4 ± 5.5 teeth and 1.1 ± 1.5 POPs. Of the 384 participants with natural teeth in each jaw, 44% had no replacements and 56% had fixed dental prostheses (FDPs), partial removable dental prostheses (PRDPs), or both. FDPs usually replaced 1 or 2 teeth, and PRDPs 3 or more teeth. On the basis of natural teeth plus artificial teeth (214 participants with replacements), 46% had functional dentitions while 18% met none of the functional criteria. In the promoted participants, the mean number of teeth added by FDPs was 3.6 ± 2.5, and for PRDPs it was 11.9 ± 6.5. FDPs had a significantly higher mean promotion value per tooth added than PRDPs. CONCLUSION: Approximately half the tooth replacements effectively met all criteria for a functional dentition.

Impression Procedures for Metal Frame Removable Partial Dentures as Applied by General Dental Practitioners.

This pilot study analyzed impression procedures for conventional metal frame removable partial dentures (RPDs). Heads of RPD departments of three dental laboratories were asked to record features of all incoming impressions for RPDs during a 2-month period. Records included: (1) impression procedure, tray type (stock/custom), impression material (elastomer/alginate), use of border-molding material (yes/no); and (2) RPD type requested (distal-extension/tooth-bounded/combination). Of the 132 total RPD impressions, 111 (84%) involved custom trays, of which 73 (55%) were combined with an elastomer. Impression border-molding material was used in 4% of the cases. Associations between impression procedure and RPD type or dentists' year/university of graduation were not found.

Dental status of an institutionalized elderly population of 60 years and over in Qingdao, China.

OBJECTIVES: The aim of this study was to investigate dental status of institutionalized elders and to relate outcomes with background variables and oral functionality. MATERIALS AND METHODS: Dental status of 512 elders (≥60 years) from eight nursing homes in Qingdao were analyzed in terms of prevalence of decayed (D), missing (M), filled (F), and replaced teeth (R). Multivariate logistic regression was applied to determine relationships with the background variables age, gender, and SES. Prevalence of D, M, and F was analyzed also for separate dental regions. For determining oral functionality, prevalence of dentitions with ≥20 teeth without and with tooth replacements was plotted against age. RESULTS: Mean number of D varied from 3.8 at 60 years to 4.6 at 90 years, M from 3.6 at 60 years to 6.7 at 90 years for the lower jaw, and from 3.0 at 60 years to 8.0 at 90 years for the upper. Mean number of F in each jaw was low: 0.2 at 60 years to 0.4 at 90 years. Gender and SES effects were limited. Molars had significantly higher prevalence of D and M than premolar and anterior teeth. Seventy percent of participants of 60 years had ≥20 natural teeth and 12 % at 90 years. Including tooth replacements, 96 % at 60 years, and 84 % at 90 years had ≥20 teeth. CONCLUSIONS: In this sample of institutionalized elders, dental status of the majority of participants did not represent a functional dentition without tooth replacements. CLINICAL RELEVANCE: Institutionalized Chinese elders showed relatively low numbers of decayed teeth but high numbers of missing teeth.

Effects of removable dental prostheses on masticatory performance of subjects with shortened dental arches: A systematic review.

OBJECTIVE: To synthesise data on the effects of distal-extension removable dental prostheses (RDPs) on masticatory performance of subjects with (extreme) shortened dental arches ((E)SDAs). DATA: Search terms were: 'masticatory' respectively 'chewing' combined with 'performance', 'efficiency', or 'ability'. SOURCES: An electronic search restricted to the years 2003-2014 in PubMed, Medline, Cochrane Library, Embase, and Science Direct databases. STUDY SELECTION: Studies exposing data on subjects with SDA (3-5 posterior occluding pairs) or ESDA (0-2 posterior occluding pairs) and on masticatory performance with RDP were included. RESULTS: Four studies provided data on comminution, three on mixing ability, and one on both tests. Comminution or mixing ability in subjects with (E)SDA was 28-39% lower compared to that of subjects with complete dentitions. In two studies, comminution outcomes when chewing with an RDP ranged from 2% to 32% reduction, indicating better chewing function (smaller X50) compared to comminution without the RDP. One study reported 28-83% lower mixing ability when chewing at the RDP side than chewing at the dentulous side. Generally, more artificial teeth (or longer occlusal platform) in experimental RDPs resulted in better comminution and better mixing ability (significant in four out of five studies), indicating a 'dose-effect' relationship. CONCLUSIONS: (1) Subjects with (E)SDA had a 30-40% reduced masticatory performance; (2) distal-extension RDPs could compensate this reduction partially (some 50%); and (3) more artificial teeth in RDPs resulted in better performance. CLINICAL SIGNIFICANCE: Distal-extension RDPs in subjects with SDA partially compensate reduced masticatory performance.

Occlusal tooth wear in patients of a dental school's prosthodontic department in Xi'an, China.

PURPOSE: To assess the relationships between occlusal tooth wear and occlusal conditions, chewing side preference, and occlusal guidance scheme. MATERIALS AND METHODS: A total of 257 Chinese adult dental school patients were categorized according to a hierarchical functional classification system. Occlusal tooth wear was assessed using a modified Smith and Knight index. Occlusal tooth wear index (OTWI) scores were analyzed using multivariate regression models, including four specific occlusal conditions (≥10 teeth in each arch, complete anterior regions, sufficient premolar regions, and sufficient molar regions) adjusted for age and sex. RESULTS: Occlusal tooth wear was observed in all participants; older participants and men had significantly higher mean OTWI scores. The occlusal condition of having fewer than 10 teeth in each arch was significantly associated with occlusal tooth wear; participants with fewer than 10 teeth in each arch had higher mean OTWI scores in anterior and premolar teeth. OTWI scores for the different tooth types were highly correlated with chewing side preference. OTWI scores for the molar region (including third molars) were significantly higher at the preferred chewing side. The same effect was seen for OTWI scores of all teeth combined. OTWI scores were not associated with occlusal guidance scheme. CONCLUSIONS: The occlusal condition of having fewer than 10 teeth in each arch appears to be a risk factor for increased occlusal tooth wear. Occlusal wear was more severe at the chewing side. Occlusal tooth wear was significantly associated with the nondental factors of age and sex.

Increased risk for premolar tooth loss in shortened dental arches.

OBJECTIVES: To assess sustainability of shortened dental arches (SDA) by determining time to 'first restorative intervention' of teeth and time to 'tooth loss' and comparing these outcomes with complete dental arches (CDA) and SDA plus removable dental prostheses (RDP). METHODS: Data (follow-up time ranged from 27.4 (SD 7.1) to 35.0 (SD 5.6) years; max. follow up: 45.8 years) from patient records of 59 subjects (23 SDA, 23 CDA, and 13 SDA plus RDP) participating in a prospective cohort study on shortened dental arches (SDA) were analysed. Group effects on survival were analysed using Cox regression models; where appropriate Kaplan-Meier analyses were done. RESULTS: Compared to SDA subjects, CDA subjects had a lower risk to receive a first restorative intervention in anterior teeth (HR=0.377; 95% CI [0.205-0.695]) and premolars (HR=0.470; 95% CI [0.226-0.977]). CDA subjects had a lower risk to lose premolars compared to SDA subjects (HR=0.130; 95% CI [0.053-0.319]). Risk for 'first restorative intervention' and for 'tooth loss' did not significantly differ between SDA with and without RDP. CONCLUSIONS: SDA subjects had an increased risk to lose premolars and to receive a first time restoration in anterior teeth and premolars compared to CDA subjects. SDA subjects with RDP had no increased risk to receive a first restorative intervention or for tooth loss compared to SDA without RDP. CLINICAL RELEVANCE: Subjects with shortened dental arches can be discerned as enduring at-risk patients. It is therefore recommended that shortened dental arch subjects receive intensive and continuous care to prevent further tooth loss.

Satisfaction with the dentition related to dental functional status and tooth replacement in an adult Bulgarian population: a cross-sectional study.

OBJECTIVES: The purpose of this study is to assess satisfaction with the dentition in general, dental esthetics, and chewing function related to dental functional status and tooth replacement in subjects, dentate in both jaws. MATERIALS AND METHODS: Dentitions of subjects (n = 2,437) aged ≥20 years were categorized in a hierarchical functional classification system, with and without tooth replacements, according to four dental conditions: '≥10 teeth in each jaw', 'complete anterior regions', 'sufficient premolar regions' (≥3 occluding pairs), and 'sufficient molar regions' (bilaterally ≥1 occluding pair). Likelihood ratios (LR) were used to express the ability of these conditions to discriminate between satisfied and not satisfied subjects. Odds ratios (OR) were calculated to evaluate associations between satisfaction, the four dental conditions separately, and tooth replacement. RESULTS: In the hierarchical system, subjects having '<10 teeth' were more likely of being not satisfied with their dentitions (LR 4.09), esthetics (LR 3.51), and chewing (LR 5.49). As a separate condition, '≥10 teeth' was significantly associated only with satisfaction with chewing. The conditions 'complete anterior regions' and 'sufficient' premolar and molar regions' were associated with all satisfaction variables (ORs 1.47-2.96, p values ≤0.012). When dental conditions were determined on the basis of natural teeth only, having teeth replaced was positively correlated with satisfaction; when determined on the basis of natural plus replaced teeth, subjects having teeth replaced tended to be less satisfied than their counterparts with natural teeth only. CONCLUSIONS: Satisfaction was strongly associated with dental functional status. CLINICAL RELEVANCE: Dental configurations comprising both natural and artificial teeth were less likely to provide the same level of satisfaction as equivalent dental configurations comprising natural teeth only.

Clinical interpretation of a masticatory normative indicator analysis of masticatory function in subjects with different occlusal and prosthodontic status.

OBJECTIVES: To analyse the masticatory function of subjects characterised by different occlusal and prosthodontic status. Using Optosil(®) as a test food, the masticatory normative indicator (MNIOPT) was used to differentiate between sufficient ('normal') and impaired masticatory function. METHODS: Outcomes of occlusal force and masticatory tests were aggregated from three earlier studies dealing with four denture groups and three natural dentition groups. The four denture groups had a complete removable dental prosthesis in the upper jaw, and displayed one of the four following lower jaw prosthodontic rehabilitations: (i) complete removable dental prosthesis on a low mandible; (ii) complete removable dental prosthesis on a higher mandible; (iii) overdenture on natural roots; and (iv) overdenture on dental implants. The three natural dentition groups were: (i) shortened dental arch; (ii) complete dentition in older participants, and (iii) complete dentition in younger participants. All participants were women. They performed the same tests twice, and outcomes were averaged. RESULTS: A MNIOPT value of 3.68 mm was determined from the participants with complete natural dentitions. Applying the MNIOPT to the participants in the denture groups pointed at a considerable chance for impaired masticatory function, except for participants in the overdenture -implants group. The four denture groups compensated for reduced masticatory efficiency by increased number of masticatory cycles and prolonged mastication time until 'swallowing'. Nevertheless, they also 'swallowed' larger particles compared to the complete dentition group. CLINICAL SIGNIFICANCE: For a given patient or for a group of subjects with specific dental conditions, MNI enables to discriminate between a sufficient ('normal') and an impaired masticatory function.

Tooth replacement related to number of natural teeth in a dentate adult population in Bulgaria: a cross-sectional study.

PURPOSE: This study aimed to explore the relationships among tooth replacement, number of present natural teeth, and sociodemographic and behavioral factors in an adult population in Bulgaria. MATERIALS AND METHODS: Quota sampling was used to recruit 2,531 dentate subjects aged 20 years and over from the capital city and four main urban centers, four towns, and seven small towns and villages of Bulgaria. Potential candidates for tooth replacement were classified as having functional dentitions (26 to 27 or 20 to 25 natural teeth present) or subfunctional dentitions (16 to 19 or 2 to 15 natural teeth present), not including third molars. Multiple logistic regression analyses were performed to determine the associations between tooth replacement and the factors of interest. RESULTS: Of the included subjects, 37% presented with tooth replacement, while 19% presented with fewer than 20 natural teeth. Molars were replaced significantly less often (P ≤ .017) than premolars and anterior teeth. The presence of tooth replacement was more likely in subjects with 2 to 15 teeth (odds ratio: 1.62) and less likely in subjects with 26 to 27 teeth (odds ratio: 0.29), but no significant difference was detected between subjects with 16 to 19 and 20 to 25 teeth. Tooth replacement was associated with age, occupational status, frequency of dental visits, and toothbrushing habits. CONCLUSIONS: In this Bulgarian population, the variables number of present teeth, age, dental visits, and toothbrushing were relevant factors with respect to tooth replacement. The cutoff value of 20 teeth did not discriminate high-risk from low-risk subjects.

Chewing ability in an urban and rural population over 40 years in Shandong Province, China.

OBJECTIVES: This study aimed to assess chewing ability related to dental status. MATERIAL AND METHODS: One thousand four hundred sixty-two Chinese subjects over 40 years, dentate in both jaws, were categorized in a hierarchical functional classification system with and without tooth replacements. Chewing ability was analyzed using multivariable logistic regression including five dental conditions ( "≥10 teeth in each jaw"; "complete anterior regions"; "sufficient premolar regions" (≥3 posterior occluding pairs (POPs)); "sufficient molar regions" (bilaterally ≥1 POP); and tooth replacement), adjusted for six background variables. Likelihood ratios for chewing problems were assessed at each level of the hierarchical classification system based on these dental conditions. RESULTS: Seventy-eight to 91 % of subjects reported no or minor chewing problems. The conditions "≥10 teeth in each jaw", and "complete anterior regions" were not associated, whereas "sufficient premolar regions" and "sufficient molar regions" were associated with chewing problems (Ors, 0.33­0.58). If classified hierarchically, the condition "≥10 teeth in each jaw" was relevant for chewing problems (likelihood ratios 3.3­3.7). "Sufficient premolar region" and "sufficient molar region" were relevant to reduce the likelihood ratios for having chewing problems (both approximately with a factor 2), both for soft and for hard foods. Subjects with artificial teeth added had similar chance for chewing problems compared to counterparts with natural teeth only. However, if comparing replaced teeth with natural teeth, subjects with tooth replacement showed higher chance for chewing problems. CONCLUSIONS: Chewing ability was strongly associated with dental conditions. CLINICAL RELEVANCE: The presence of at least 10 teeth in each jaw had highest impact on chewing ability.

An observational cohort study on shortened dental arches--clinical course during a period of 27-35 years.

OBJECTIVES: The objective of this study was to investigate the clinical course of shortened dental arches ('SDA group') compared to SDAs plus removable denture prosthesis ('SDA plus RDP group') and complete dental arches ('CDA group', controls). MATERIALS AND METHODS: Data (numbers of direct and indirect restorations, endodontic treatments, tooth loss and tooth replacements) were extracted from patient records of subjects attending the Nijmegen Dental School who previously participated in a cohort study on shortened dental arches with three to four posterior occluding pairs (POPs). RESULTS: Records of 35 % of the original cohort were retrievable. At the end of the follow-up (27.4 ± 7.1 years), 20 out of 23 SDA subjects still had SDA with 3-4 POPs compared to 6 out of 13 for SDA plus RDP subjects (follow-up 32.6 ± 7.3 years). Sixteen out of 23 CDA subjects still had CDA; none of them lost more than one POP (follow-up 35.0 ± 5.6 years). SDA group lost 67 teeth: 16 were not replaced, 16 were replaced by FDP and 35 teeth (lost in three subjects) replaced by RDP. Mean number of treatments per year in SDA subjects differed not significantly compared to CDA subjects except for indirect restorations in the upper jaw. CONCLUSION: Shortened dental arches can last for 27 years and over. Clinical course in SDA plus RDP is unfavourable, especially when RDP-related interventions are taken into account. CLINICAL RELEVANCE: The shortened dental arch concept seems to be a relevant approach from a cost-effective point of view. Replacement of absent posterior teeth by free-end RDP cannot be recommended.