Three-dimensional finite element analysis of implant-assisted removable partial dentures

Statement of problem

Whether the implant abutment in implant-assisted removable partial dentures (IARPDs) functions as a natural removable partial denture (RPD) tooth abutment is unknown.

A clinical investigation of the relationship between the quality of conventional complete dentures and the patients’ quality of life

Objective

The purpose of this study was to determine whether there is a correlation between the clinical quality of conventional complete dentures and patient quality of life.

Materials and methods

This study included a random sample of 32 completely edentulous patients (15 males and 17 females) who were treated with conventional complete dentures. Using a validated questionnaire, three investigators evaluated the dentures independently on the basis of seven clinical parameters: esthetics (lip support and lower lip line), retention and stability of the maxillary and the mandibular dentures, and occlusion. Patients completed the validated Oral Health Impact Profile-20 (OHIP-20) questionnaire. Correlations were determined by using the point-biserial correlation coefficient.

Results

Clinicians rated the overall clinical quality of the dentures satisfactory in 80.3% of patients. The mean (±standard deviation) total OHIP-20 score was 56.3 ± 15.9 out of a possible 120 maximum. A statistically significant negative correlation was found between the stability of the maxillary and mandibular dentures and the total OHIP-20 score (p = 0.009 and 0.0023, respectively). A negative correlation between the total OHIP-20 score and the retention of the mandibular denture approached significance (p = 0.092). Esthetics, retention of the maxillary denture, and occlusion were not correlated with patient quality of life (p > 0.169).

Conclusion

Stability of the maxillary and mandibular dentures is the denture quality parameter that can most significantly affect patient quality of life.     

Patient satisfaction with laser-sintered removable partial dentures: A crossover pilot clinical trial

Statement of problem

Clinical data regarding newly introduced laser-sintered removable partial dentures (RPDs) are needed before this technique can be recommended. Currently, only a few clinical reports have been published, with no clinical studies.

Effect of three investing materials on tooth movement during flasking procedure for complete denture construction

Problem statement

Tooth movement has been shown to occur during and after the processing of complete dentures. An understanding of this phenomenon may permit one to construct functional complete dentures that require less occlusal adjustment in the articulator and in the patient’s mouth.

Purpose

The purpose of this study was to examine the effects of three different investing methods on tooth movement occurring during the processing of simulated maxillary complete dentures.

Material and methods

Forty-five similar maxillary dentures were made using heat-polymerized acrylic resin, and assigned randomly to three experimental groups (n = 15 each) according to investing method: plaster–plaster–plaster (P–P–P), plaster–stone–stone (P-S-S), and plaster–mix (P–M). Specimens in all experimental groups were compression molded with denture base resin. Transverse interincisor (I–I) and intermolar (M–M) distances, and anteroposterior incisor–molar (LI–LM and RI–RM) distances, were measured with digital calipers at the wax denture stage (pre-polymerization) and after denture decasting (post-polymerization). Analysis of variance and Tukey’s test were used to compare the results.

Results

M–M, LI–LM, and RI–RM movement was significantly greater in the P–P–P group than in the P–S–S and P–M groups; no significant difference in I–I movement was observed among groups. Transverse movement along M–M and I–I was significantly greater than anteroposterior movement in the P–P–P group; no significant difference among measurements was observed in the other two groups.

Conclusion

The study results indicate that the use of dental stone or a 50:50 mixture of plaster and stone for investing of dentures is an important factor in efforts to control the magnitude of tooth movement.     

The impact of frenulum height on strains in maxillary denture bases

PURPOSE

The midline fracture of maxillary complete dentures is a frequently encountered complication. The purpose of this study was to assess the effect of frenulum height on midline strains of maxillary complete dentures.

MATERIALS AND METHODS

A removable maxillary complete denture was fabricated and duplicated seven times. Four different labial frenulum heights were tested for stresses occurring on the palatal cameo surface. The strains were measured with strain gauges placed on 5 different locations and the stresses were calculated. To mimic occlusal forces bilaterally 100 N of load was applied from the premolar and molar region.

RESULTS

A statistically significant association between the height of the labial frenulum and the calculated stresses and strains was shown (P<.05) predominantly on the midline and especially on the incisive papilla. The results showed that stress on the anterior midline of the maxillary complete denture increases with a higher labial frenulum.

CONCLUSION

Within the limitations of this in vitro study, it can be concluded that the stress on the anterior midline of the maxillary complete denture increases with a higher labial frenulum. Surgical or mechanical precautions should be taken to prevent short-term failure of maxillary complete dentures due to stress concentration and low cycle fatigue tendency at the labial frenulum region.     

Elastic modulus and flexural strength comparisons of high-impact and traditional denture base acrylic resins

Background

Fractures of acrylic resin dentures are a common occurrence in clinical dentistry. The denture may be fractured accidentally when dropped or while in service in the mouth due to flexural fatigue.

Objectives

The aim of this study was to compare the elastic modulus and the flexural strength between two heat-cured acrylic resins used in denture bases: a high-impact resin (Lucitone 199) and a traditional resin (Rodex).

Materials and methods

Rectangular strips of Lucitone 199 and Rodex (10 samples each) were fabricated and stored in artificial saliva at 37 °C for 2 weeks. The specimens were subjected to a three-point flexural test. The data were statistically analysed with Student’s t-test (p ⩽ .05).

Results

The high-impact acrylic resin had a lower elastic modulus (p = .000) and higher flexural strength (p = .001) compared to the traditional acrylic resin.

Conclusion

Within the limitations of this study, it can be concluded that the high-impact acrylic resin is a suitable denture base material for patients with clinical fracture of the acrylic denture.     

Impact of removable partial denture prosthesis on chewing efficiency

Removable partial denture prostheses are still being used for anatomic, medical and economic reasons. However, the impact on chewing parameters is poorly described.

Objectives

The objective of this study was to estimate the impact of removable partial denture prosthesis on masticatory parameters.

Material and Methods

Nineteen removable partial denture prosthesis (RPDP) wearers participated in the study. Among them, 10 subjects were Kennedy Class III partially edentulous and 9 with posterior edentulism (Class I). All presented a complete and full dentate opposing arch. The subjects chewed samples of carrots and peanuts with and without their prosthesis. The granulometry of the expectorated boluses from carrot and peanuts was characterized by median particle size (D50), determined at the natural point of swallowing. Number of chewing cycles (CC), chewing time (CT) and chewing frequency (CF=CC/CT) were video recorded.

Results

With RPDP, the mean D50 values for carrot and peanuts were lower [Repeated Model Procedures (RMP), F=15, p<0.001] regardless of the type of Kennedy Class. For each food, mean CC, CT and CF values recorded decreased (RMP, F=18, F=9, and F=20 respectively, p<0.01). With or without RPD, the boluses'' granulometry values were above the masticatory normative index (MNI) determined as 4,000 µm.

Conclusion

RPDP rehabilitation improves the ability to reduce the bolus particle size, but does not reestablish fully the masticatory function.

Clinical relevance

This study encourages the clinical improvement of oral rehabilitation procedure.     

Complication rates and patient satisfaction with removable dentures

PURPOSE

The purpose of this clinical study was to evaluate the frequency and type of prosthetic complications in relation to type and properties of removable dentures and to investigate the influence of these complications and several data about the existing dentures on patient satisfaction.

MATERIALS AND METHODS

Ninety nine patients (44 males and 55 females) wearing removable dentures have been included in the study. The complications of the patients were recorded; patient satisfaction was determined with a Visual Analog Scale (VAS) and the relationship of complications and patient satisfaction with several data about the dentures such as denture age, type of denture, centric relation and vertical dimension was investigated. Kruskal Wallis, Mann Whitney U and Chi square tests were used for statistical analyses. The results were evaluated statistically at a significance level of P<.05.

RESULTS

Need for addition of artificial teeth for dentures with correct centric relations was found to be significantly lower than dentures with wrong centric relations (P<.01). Loss of retention, ulcerations and high vertical dimension affected the VAS chewing ability scores negatively and ulcerations affected the VAS phonation scores negatively (P<.05).

CONCLUSION

Considering the results of this study, it can be concluded that loss of retention, ulcerations and high vertical dimension caused patient dissatisfaction. Additionally, dentures with wrong centric relations caused need for addition of artificial teeth.     

In vivo efficacy of alkaline peroxide tablets and mouthwashes on Candida albicans in patients with denture stomatitis

Objective

Effective cleaning of dentures is important for the maintenance of good oral hygiene for denture stomatitis patients. The in vivo efficacy of three different brands of alkaline peroxide tablets (Polident, Efferdent, and Fittydent) and two mouthwashes (CloSYS II and Corsodyl) to eliminate Candida albicans on dentures was evaluated in this in vivo study.

Material and methods

Ninety denture wearers with clinical evidence of denture stomatitis were randomly divided into 5 test groups and 1 control group. Each group was further divided into three subgroups in which the dentures were subjected to 15-, 30-, and 60-min disinfection procedures. The dentures of each test group were treated with one of the cleaners, while those of the control group were treated with distilled water. Swab samples from the palatal surfaces (2 cm x 2 cm template delimited area) of the upper dentures were obtained before and after 15, 30, and 60 min periods of cleaner use and examined mycologically.

Results

The reduction in the number of colony-forming units (CFU) of C. albicans before, and after 15, 30, and 60 min of use of CloSYS II and Corsodyl was significantly greater than that of the control group (p<0.05). Moreover, there was no statistically significant difference (p>0.05) among Polident, Efferdent and the control group in any of the treatment periods. Dentures treated with Fittydent appeared to have a significantly greater reduction in the number of Candida spp. only after 60 min of treatment.

Conclusions

The results of this study showed that the use of mouthwashes significantly reduced the number of microorganisms on dentures.     

A comparative study of two different clear aligner systems

Background

This study aims to compare the ‘Nuvola®’ system with ‘Fantasmino®’ system, examine their material properties, and define the indications for use of the aligners.

Methods

Two groups of patients were selected and were respectively treated with Nuvola® aligner and Fantasmino® system.

Results

The goal of treatment has been achieved with the two systems.

Conclusions

The two types of aligners have shown differences during the treatment. Fantasmino® system has elastic properties of high performance, but its size does not encourage compliance throughout the day. Nuvola® system determines good tooth movement and its size facilitates the patient’s collaboration. In both aligner systems, difficulties were found in the correction of torque information and rotations.     

A Survey of Removable Partial Denture (RPD) Retentive Elements in Relation to the Type of Edentulism and Abutment Teeth Found in Commercial Laboratories,Athens, Greece

Objective

The aim of this survey was to record removable partial denture (RPD) retentive elements and abutment teeth in partially edentulous patients, identified in commercial laboratories in Athens, Greece.

Material and Methods

628 master casts with the corresponding cast metal frameworks used in the construction of RPDs were evaluated. Casts were photographed to identify the number and position of existing teeth, the partial edentulism class and the retentive elements. Prevalence tables and the x² test were used for the statistical analysis of the collected data (α=.05).

Results

There were 276 maxillary (43.9%) and 352 (56.1%) mandibular casts. Maxillary edentulism entailed almost a total absence of right third molars in 96.7% and left third molars 96.0% of casts, with lower rates for the first and second molars. Edentulism in the posterior mandible presented a similar pattern. The most profound findings concerning retentive elements were: 91.9% of the retainers used were clasps and the remaining 8.1% were attachments. Of the clasps used, 48.9% were of the Roach Τ type, a finding more common in Kennedy Class I as compared to other Kennedy Classes (p<0.01). The circumferential clasps accounted for 19.3% of the total clasps used, and it was less frequently presented (8.8%) in Kennedy I Classes (p<0.01).

Conclusions

Roach clasps were used in the majority of cases whereas RPI clasps and attachments were rarely used.Key words: Kennedy classification, retentive elements, remaining teeth     

Full mouth rehabilitation of destroyed dentition with rotational path removable partial denture: a case report

BACKGROUND

Though implant dentistry is very successful and predictable in treatment of patients with destroyed dentition, there are some cases with limitations to implant therapy. In these cases, alternative treatment modality should be considered.

CASE DESCRIPTION

A patient with destroyed dentition was rehabilitated with a lateral rotational path removable partial denture. According to the diagnosis, we determined to raise vertical dimension for esthetic and functional restoration. The final restoration was performed after four months of provisional period.

CLINICAL IMPLICATION

The edentulous patients with compromised esthetics and functions can be successfully treated with a rotational path removable partial denture through adequate treatment planning and precise laboratory procedure.     

Assessment of swallowing and masticatory performance in obturator wearers: a clinical study

PURPOSE

To assess function by identifying changes in swallowing and masticatory performance in maxillary obturator prosthesis wearers.

MATERIALS AND METHODS

Sixty subjects were recruited for the study, of which 20 were obturator wearers, 20 were completely dentulous and 20 had removable partial/complete dentures with similar Eichner''s Index. Swallowing ability was evaluated with and without obturator using the "Water Drinking Test"; Masticatory performance was evaluated with the Sieve test; and maximum occlusal force was recorded with the help of a digital bite sensor. The data was analyzed using the Statistical Package for Social Science version 15.0 with a confidence level at 95%.

RESULTS

Profile, behavior of drinking and time taken to drink were significantly improved (P<.001) in subjects after wearing obturator. Masticatory performance was not significantly different (P=.252) in obturator wearer when compared with dentulous or removable partial/complete denture wearer, but significantly (P<.001) high inter group difference in maximum occlusal force existed. Correlation between masticatory performance and maximum occlusal force was not significant (P=.124).

CONCLUSION

Swallowing ability was significantly improved after wearing obturator but masticatory performance was not significantly different from those having similar occlusal support zone in their dentition.     

EFFECT OF THERMOCYCLING ON THE TENSILE AND SHEAR BOND STRENGTHS OF THREE SOFT LINERS TO A DENTURE BASE RESIN

Statement of problem

In clinical practice, loss of adhesion between the silicone-based denture liner and the denture base resin is always an undesirable event that might cause loss of material softness, water sorption, bacterial colonization and functional failure of the prosthesis.

Purpose

This study evaluated the effect of thermocycling on tensile and shear bond strengths of three soft liner materials to a denture base acrylic resin.

Material and methods

Three resilient liners (Mucopren-Soft, Mollosil-Plus and Dentusil) and a heat-polymerized acrylic resin (QC-20) were processed according to manufacturers’ directions. Sixty specimens (14 x 14 mm cross-sectional area) per bond strength test (20 for each liner) were fabricated and either stored in water at 37°C for 24 hours (control groups; n=10) or thermocycled 3,000 times in water between 5°C and 55°C (test groups; n=10). The specimens were tested in tensile and shear strength in a universal testing machine until fracture. Bond strength means were compared between water-stored and thermocycled groups for each material, as well as among materials for each treatment (water storage or thermocycling). Failure mode (adhesive, cohesive and mixed) after debonding was assessed. Data were analyzed statistically by paired Student’s t-test and ANOVA at 5% significance level.

Results

The water-stored groups had statistically significant higher bond strengths than the thermocycled groups (p<0.05). Without thermocycling, Mucopren-Soft (2.83 ± 0.48 MPa) had higher bond strength than Mollosil-Plus (1.04 ± 0.26 MPa) and Dentusil (1.14 ± 0.51 MPa). After thermocycling, Mucopren-Soft (1.63 ± 0.48 MPa) had the highest bond strength (p<0.05).

Conclusion

The bond strength of the three soft denture liners tested in this study changed with their chemical composition and all of them exhibited higher bond strengths than those usually reported as clinically acceptable.

Clinical Implications

All soft lining materials tested in this study showed a significant decrease in the bond strength to an acrylic denture base resin after thermocycling. In spite of thermocycling, though, the silicone-based liners had satisfactory bond strengths for clinical application.     

An investigation into the effect of denture adhesives on incisal bite force of complete denture wearers using pressure transducers - a clinical study

PURPOSE

Study was conducted to determine and assess the effect of different type of denture adhesives on the incisal bite force of complete denture wearers until the dislodgement of upper denture, using pressure transducer.

MATERIALS AND METHODS

30 patients out of 100 were included in the study. Based on the Kapur''s method of scoring denture retention and stability, these patients were divided into 3 groups- Group A - Clinically good dentures; Group B - Clinically fair dentures; and Group C - Clinically poor dentures. A custom made occlusal force meter was constructed based on the load cell type of pressure transducers. Different adhesives (powder, paste and adhesive strips) were used in the study. Complete denture wearers were asked to bite on the load cell and the readings of incisal bite force were recorded. The readings of incisal bite force were subjected to statistical analysis using Repeated measures ANOVA followed by post-hoc bonferroni test.

RESULTS

The result suggests that denture adhesives improved the incisal bite force of complete denture wearers significantly The incisal bite force (in kg) in Group A without using adhesives, with powder adhesive, with paste adhesive and with adhesive strips was found to be 2.48 (± 0.16), 3.43 (± 0.11), 6.01 (± 0.11), 3.22 (± 0.09) respectively. The incisal bite force (in kg) in Group B without using adhesives, with powder adhesive, with paste adhesive and with adhesive strips was found to be 1.87 (± 0.18), 3.35 (± 0.14), 5.34 (± 0.18), 3.21 (± 0.12) respectively. The incisal bite force (in kg) in Group C without using adhesives, with powder adhesive, with paste adhesive and with adhesive strips was found to be 1.00 (± 0.17), 3.07 (± 0.14), 4.37 (± 0.26), 2.99 (± 0.14) respectively.

CONCLUSION

Within the limitations of the study, it was concluded that the use of denture adhesive was found to be significantly effective in improving the incisal bite force of complete dentures until the dislodgement of upper denture. Fittydent paste adhesive was found to be more effective than the powder and strips adhesives. The improvement in incisal bite force was found to be higher in Group C in comparison to that of Group A and Group B.     

Effect of two heat treatments on mechanical properties of selective-laser-melted Co-Cr metal-ceramic alloys for application in thin removable partial dentures

Statement of problem

Heat treatment has been used to reduce the residual stress of alloys fabricated by selective laser melting (SLM) to avoid deformation. Co-Cr metal-ceramic alloys are used to fabricate metal-ceramic restorations and removable partial dentures (RPDs) on the same substrate by SLM. A heat treatment that enables the fabrication of metal-ceramic restorations and RPDs with excellent mechanical properties should be evaluated.

Accuracy of CAD-CAM-fabricated removable partial dentures

Statement of problem

The conventional fabrication of removable partial dentures (RPDs) is a complex, error-prone, time-consuming, and expensive process. The use of computer-aided design and computer-aided manufacturing (CAD-CAM) techniques, especially rapid prototyping, promises a more effective method for fabricating RPD frameworks.

ENTEROBACTERIACEAE AND PSEUDOMONADACEAE ON THE DORSUM OF THE HUMAN TONGUE

Objective:

The aim of this study was to correlate the presence of Enterobacteriaceae, Pseudomonadaceae, Moraxellaceae and Xanthomonadaceae on the posterior dorsum of the human tongue with the presence of tongue coating, gender, age, smoking habit and denture use.

Material and Methods:

Bacteria were isolated from the posterior tongue dorsum of 100 individuals in MacConkey agar medium and were identified by the API 20E system (Biolab-Mérieux).

Results:

43% of the individuals, presented the target microorganisms on the tongue dorsum, with greater prevalence among individuals between 40 and 50 years of age (p = 0.001) and non-smokers (p=0.0485).

Conclusions:

A higher prevalence of Enterobacteriaceae and Pseudomonadaceae was observed on the tongue dorsum of the individuals evaluated. There was no correlation between these species and the presence and thickness of tongue coating, gender and presence of dentures.     

Nebulisation Versus Spray-as-You-Go Airway Topical Anaesthesia in Patients with Temporomandibular Joint Ankylosis using 2?% Lignocaine

Study Design

This randomized, comparative clinical study was designed to compare 2 % lignocaine nebulization and 2 % lignocaine via spray-as-you-go technique for topical airway anaesthesia during or awake flexible fiberoptic intubation (AFOI) in temporomandibular joint (TMJ) ankylosis patients.

Methods

Sixty adult patients with TMJ ankylosis were randomly assigned to the following study groups using a computer generated random number table 2 % lignocaine nebulised (group A) and 2 % lignocaine via spray-as-you-go technique (group B). After airway anaesthesia, awake flexible fiberoptic nasotracheal intubation was performed. An independent investigator who did not participate in the study scored patients’ comfort during airway topical anaesthesia and patients’ reaction during awake FOI. Changes in haemodynamics during the airway manipulation were also observed.

Results

There were no statistically significant differences in the observed variables between the two groups.

Conclusions

Both 2 % lignocaine nebulization and 2 % lignocaine spray-as-you-go technique provided acceptable conditions for AFOI in TMJ patients.