Finite Element Analysis of Implant-Assisted Removable Partial Denture Attachment with Different Matrix Designs During Bilateral Loading

PURPOSE

The aim of this study was to investigate the effect of different matrix designs on resilient attachment on an implant-assisted removable partial denture (IARPD) using finite element analysis (FEA).

MATERIALS AND METHODS

A laser scanner was used to extract the geometrical data of a human partially edentulous mandible. A 12-mm-long and 4.8-mm-diameter-wide implant was modeled, and two types of intradental attachment of snap fastener principle (elliptical) and resilient attachment (titanium) matrices were modeled along with tooth roots and periodontal ligaments. The modeling was performed with a combination of reverse engineering and solid modeling. The model incorporated a removable partial denture and was loaded with realistic bilateral forces. The FEA was used to analyze the stress and strain distributions in the IARPD and in the metal framework.

RESULTS

Stresses and deformations in the metal framework and resin denture base surfaces were analyzed for the elliptical and titanium matrix designs. The maximum von Mises stresses were 605.85 and 614.96 MPa in the metal framework surface and 10.35 and 10.63 MPa in the resin denture base surface, respectively, for the elliptical and titanium matrix designs. The maximum deformations (displacements) were 418.5 and 428.3 μm in the metal framework surface for the elliptical and titanium matrix designs, respectively. The corresponding values of displacements for the resin denture base surface were 325.52 and 249.22 μm for the elliptical and titanium matrix designs, respectively. The maximum displacements in the matrixes were, however, nearly the same (229.51 and 229.47 μm) for both the elliptical and titanium matrixes.

CONCLUSION

The titanium matrix design was a more favorable design compared with the elliptical design, because it had lower lateral deformation as indicated by the maximum displacement.

Association Between Dentition Status and Malnutrition Risk in Serbian Elders

PURPOSE

The aim of this study was to find the correlation between the number, type, and placement of symmetric functional tooth units and the nutritional status using body mass index (BMI) and Mini Nutritional Assessment (MNA) in patients with both maxillary and mandibular removable partial dentures.

MATERIALS AND METHODS

A randomized study was conducted at the Clinic for Prosthodontics, School of Dentistry, University of Belgrade, Serbia, followed by determination of number of functional tooth units. After insertion of the prostheses, the nutritional status was assessed, using BMI and MNA form. Nutritional status was reviewed 12 months after prosthetic treatment. Number of teeth and age were analyzed using analysis of variance and t test. For other variables such as BMI baseline, BMI follow-up, MNA baseline, MNA follow-up, change in BMI, and change in MNA, Kruskal-Wallis Test or Mann-Whitney Test were used.

RESULTS

The results on the MNA changes showed that patients with symmetric natural functional tooth units had significantly higher values (2.9 ± 0.8) compared with patients without natural functional tooth units (1.9 ± 0.6) or with asymmetric natural functional tooth units (1.6 ± 0.4). Patients with asymmetric artificial functional tooth units had significantly lower change in MNA (1.9 ± 0.4) than those with symmetric artificial functional tooth units (2.6 ± 0.9).

CONCLUSION

The findings of this study suggest that adequate rehabilitation with symmetric positioning of the functional tooth units can improve the nutritional status of partially edentulous patients.

[Impact of the edentulousness on the quality of life related to the oral health of the Congolese]

BACKGROUND

No studies on the perception of tooth loss effects in their daily lives of edentulous were performed in Congolese Bantu.

OBJECTIVES

To assess the severity of the impact of edentulism on the quality of life of partially edentulous Congolese and analyze the influence of age, sex, missing teeth, the location of gaps and pairs of posterior dental occlusion in this impact.

METHOD

This descriptive cross-sectional study was conducted in the University Clinics of Kinshasa (CUK) and the Centre Boyambi Army Hi Kinshasa/Gombe. One hundred and eighty one edentulous adults and non-denture wearers clinically examined were asked to complete the questionnaire OHIP 14.

RESULTS

Average severity was 11.67 ± 8.74 on a scale of 0-56. Statistically missing teeth, location of gaps and pairs of posterior dental occlusion residual alter this severity. The poor quality of life was noted in patients who had lost more than 5 teeth (17.04 ± 7.26), anterior losses (17.32 ± 9.42) and less than 4 pairs of posterior occlusion (17.84 ± 6.13). Difficult chewing and concern were the most reported items.

CONCLUSION

Severity of the influence of tooth loss on the daily life of Congolese people is low. All edentulous does not necessarily cause a very poor quality of life. Increasing the number of lost teeth, presence of anterior gaps and reduction of posterior occlusion pairs below 4 disrupt the quality of life of partially edentulous.

Maxillary implant-retained partial overdenture with Dolder bar attachment: a clinical report

This article describes a technique for maintaining a maxillary Kennedy III partial removable dental prosthesis design in a patient who had non-restorable failing abutments by replacing the abutments with dental implants. Two implants were placed immediately after extraction of the abutment teeth in the anterior maxilla. After the implants were fully integrated, a Dolder bar attachment was fitted onto the implants. A new maxillary partial removable dental prosthesis was fabricated using the implants and the remaining natural teeth as abutments to restore function and esthetics. With the aid of dental implants, this Kennedy III maxillary removable dental prosthesis design could provide additional retention and support by promoting cross-arch stability and tissue, implant and tooth support. The patient's satisfaction was significantly increased.

Theoretical role of adjunctive implant positional support in stress distribution of distal-extension mandibular removable partial dentures

This preliminary study evaluated the adjunctive supporting role of diverse implant positions on stress distribution in a Class I removable partial denture (RPD) design. Nine three-dimensional finite element models were prepared to simulate mandibular RPD designs with three different loading conditions applied. Implant supported designs demonstrated lower stress value concentrations and mucosal displacement.

Minimal intervention dentistry and older patients part 2: minimally invasive operative interventions

As described in the first paper of this two part series, the expansion of our older population and the concomitant reduction in levels of edentulism will result in an increase in the number of patients presenting in general practice with complex restorative challenges. The application of the concepts of minimal intervention dentistry and minimally invasive operative techniques may offer a powerful armamentarium to the general dentist to provide ethical and conservative treatment to older patients.

CLINICAL RELEVANCE

When it is unavoidable, operative intervention should be as minimally invasive as practicable in older patients to preserve the longevity of their natural dentition.

Finite element analysis of an implant-assisted removable partial denture during bilateral loading: occlusal rests position

STATEMENT OF PROBLEM

When implants are incorporated into an existing partial removable dental prosthesis, the acrylic resin base can fracture. It is therefore essential to study the mechanical behavior of partial removable dental prostheses by using stress and deformation analysis.

PURPOSE

The purpose of this study was to analyze the effect of the occlusal rest position on the implant-assisted partial removable dental prosthesis by finite element analysis.

MATERIAL AND METHODS

A Faro Arm scan was used to extract the geometrical data of a human partially edentulous mandible. A standard plus regular neck (4.8×12 mm) implant and titanium matrix, tooth roots, and periodontal ligaments were modeled by using a combination of reverse engineering in Rapidform XOR2 and solid modeling with the Solid Works CAD program. The model incorporated a partial removable dental prosthesis and was loaded with standard bilateral forces. A uniform pressure was applied on the occlusal surface so as to generate an equivalent net force of 120 N for both the left and right prosthesis. The finite element analysis program ANSYS Workbench was used to analyze the stress and strain distributions in the implant-assisted partial removable dental prosthesis.

RESULTS

Maximum stresses were significantly high for the metal framework compared to the acrylic resin surface, and these stresses were different for the mesial and distal arm designs. The maximum stress in the metal framework for the mesial arm design was 614.9 MPa, and it was 796.4 MPa for the distal arm design. The corresponding stresses in the acrylic resin surface were 10.6 and 8.6 MPa.

CONCLUSIONS

Within the limitation of this study, it was found that moving the position of the occlusal rest from the mesial to distal side of the abutment teeth improved the stress distribution in the metal framework and acrylic resin denture base structures.

[Rehabilitation by composite prosthesis combining milling of embedded bilateral edentulous: a clinical report]

The treatments with composite prosthesis require the completion of milling. These precision preparations in the fixed prosthesis promote the integration of removable partial denture with metallic framework in mechanical (prosthetic balance), physiological, aesthetical and psychological point of view. Their conception and realization are always subordinated to the balance principles of the removable partial denture. The precision they require need the use of a dental milling machine working along the predetermined insertion axis of the partial denture casting and require an excellent communication and a close collaboration between dentist and experienced technician of laboratory. In this paper, after a recalling about the milling (definition, description, interests), we will detail the steps to achieve clinical and laboratory needs for a rehabilitation by composite prosthesis combining milling, and it will be illustrated through a clinical case with a bilateral tooth-supported edentulous in the maxilla.

A hinged two-part partial denture used in conjunction with severely tilted teeth: a case report

A two-part sectional denture can be a useful treatment option when the presence of severe hard tissue undercuts compromises the provision of a satisfactory conventional prosthesis. This article presents a case report illustrating the effective use of a hinged two-part denture in restoring a mandibular Kennedy Class IV edentulous area. A sectional denture approach was selected because of severe proximal and lingual undercuts.

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.

Removable partial dentures: clinical concepts

This article provides a review of the traditional clinical concepts for the design and fabrication of removable partial dentures (RPDs). Although classic theories and rules for RPD designs have been presented and should be followed, excellent clinical care for partially edentulous patients may also be achieved with computer-aided design/computer-aided manufacturing technology and unique blended designs. These nontraditional RPD designs and fabrication methods provide for improved fit, function, and esthetics by using computer-aided design software, composite resin for contours and morphology of abutment teeth, metal support structures for long edentulous spans and collapsed occlusal vertical dimensions, and flexible, nylon thermoplastic material for metal-supported clasp assemblies.

Self-perceived changes in oral health-related quality of life after receiving different types of conventional prosthetic treatments: a cohort follow-up study

OBJECTIVES

To evaluate the changes in oral health-related quality of life (OHRQoL) reported by subjects treated with conventional prostheses.

METHODS

A consecutive sample of 153 patients seeking prosthodontic rehabilitation was recruited. Socio-demographic and prosthetic-related factors (Eichner Index; number of occlusal, aesthetic, and lost units) were registered. Baseline impacts on OHRQoL were collected using the OHIP-14 questionnaire. One month after treatment, the participants answered whether the prostheses had generated better, equal, or poorer effects within the 14 items of a retrospective scale (Post-OHIP). The study patients were compared with the reference population (P-population; n=123) in terms of OHRQoL. Such P-population consisted of Spanish adults wearing conventional dental prostheses who were not seeking any dental treatment. The reliability and validity of the tests applied and the factor structure of the Post-OHIP were investigated. A Poisson regression model was calculated to predict what items would change favourably after treatment.

RESULTS

Four prosthetic cohorts were established according to the types of rehabilitations performed: 1-FDPs: metal-ceramic fixed dental prostheses; 2-M-RPDs: metal-based removable partial dentures; 3-ADs: acrylic partial dentures and 4-CDs: complete dentures. Both tests confirmed adequate psychometric properties. Most items of the Post-OHIP consistently loaded on a single factor. Patients requiring ADs or CDs reported significantly lower baseline OHRQoL than those needing M-RPDs or FDPs. Pain/discomfort was the only hampering issue subsequent to removable rehabilitation. M-RPDs are expected to provide the significantly highest therapeutic improvements.

CONCLUSIONS

Patients perceived benefits in chewing ability, aesthetics and satisfaction with their mouth after receiving conventional dental prostheses.

CLINICAL SIGNIFICANCE

Conventional prosthetic therapy enhances patients' overall well-being although it can cause discomfort and chewing dysfunction in more than 20% of subjects. Metal-based removable partial dentures are the most predictable in terms of patient satisfaction. The higher the clinical impairment felt by patients, the higher the increase in OHRQoL after rehabilitation.

Long-term follow-up of conical crown-retained dentures fabricated using different technologies

This study presents the results of a long-term clinical evaluation of conical crown-retained dentures fabricated using different technologies. Four different material connections between the outer and inner crowns were used: cast gold/cast gold, cast gold/electroforming, nonprecious alloy/electroforming, and titanium abutment/electroforming. Technical failures and retention values were assessed. The best clinical outcome was found with dentures in which both crowns were cast from gold alloy. The most frequent technical failures were observed in restorations with electroformed outer crowns. Better clinical outcomes were noted when the electroformed outer crowns were used in dentures retained by implants as compared to dentures on natural dentition.

Clinical performance of cast clasp-retained removable partial dentures: a retrospective study

PURPOSE

This retrospective study investigated the survival rate of 174 clasp-retained removable partial dentures (CR-RPDs) made at the Department of Prosthodontics of the Regensburg University Medical Center over a 25-year period (1984 to 2009).

MATERIALS AND METHODS

The study analyzed the frequency of and time to the fracture of clasps, connectors, or denture bases; the occurrence of caries or periodontal lesions; the loss of abutment teeth; and the necessity of maintenance procedures such as relining or treatment of pressure areas.

RESULTS

The median follow-up time of 3 years was calculated using the inverse Kaplan-Meier method. The 5-year survival rate (time to renewal) of all CR-RPDs was 96.4%; the 10-year survival rate was 89.8%. Fractures most frequently occurred in clasps (n = 28, 16.1%) followed by major connectors (n = 9, 5.1%) and minor connectors (n = 6, 3.4%). The 5-year event-free rate for clasp fracture was 80.4%; the 10-year event-free rate was 76.9%. Caries lesions on abutment teeth were seen in 31.6% of patients, and 35.6% showed inflammation of the periodontal tissue surrounding the abutment teeth. The 5-year event-free rate for caries was 58.4%; the 10-year rate was 39.6%. A frequent complication was loss of abutment teeth (n = 15), but this complication was not age-dependent. After insertion of their prostheses, one-third of patients (n = 53, 30.5%) showed pressure areas of the mucosa. Significantly more (P < .001) pressure areas were caused by prostheses of the mandible (39.6%) than by those of the maxilla (12.5%).

CONCLUSIONS

CR-RPDs showed a survival rate of approximately 90% after 10 years of oral service. The predominant complications during oral service were caries lesions, loss of abutment teeth, and fracture of clasps.

Factors associated with self-assessed masticatory ability among community-dwelling elderly Japanese

Self-assessed masticatory ability has been shown to be significantly related to general health among elderly persons.

OBJECTIVE

To identify oral factors associated with the self-assessed masticatory ability.

BASIC RESEARCH DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 736 community-dwelling elderly persons.

MAIN OUTCOME MEASURES

Data on background factors and the self-assessed masticatory ability were collected by questionnaire. An intraoral examination examined the pattern of posterior occluding pairs of natural teeth (POPs), the WHO Community Periodontal Index of Treatment Needs (CPI) and denture-related factors such as use of dentures, pain when using dentures and stability and retention of dentures. Chi-squared tests examined the relationships between the self-assessed masticatory ability and the background factors and oral conditions. Ordinal regression models were constructed with the self-assessed masticatory ability as the dependent variable and oral conditions as the principal independent variables, to adjust for the potential confounding variables.

RESULTS

Self-assessed impairment of masticatory ability was associated with lost POPs (p < 0.001) and CPI (p = 0.012). In the participants with lost POPs, self-assessed impairment of masticatory ability was associated with not using dentures and pain when using dentures (p < 0.001). In the totally edentulous subjects, impairment of masticatory ability was not associated with stability and retention of dentures (p = 0.070).

CONCLUSIONS

Factors affecting self-assessed masticatory ability include the pattern of POPs, periodontal status, denture use and pain when using dentures.

Speech intelligibility enhancement through maxillary dental rehabilitation with telescopic prostheses and complete dentures: a prospective study using automatic, computer-based speech analysis

PURPOSE

A completely edentulous or partially edentulous maxilla involving missing anterior teeth may impact speech production and lead to reduced speech intelligibility. The aim of this study was to prospectively evaluate the effect of a dental prosthetic rehabilitation on speech intelligibility in patients with a toothless or interrupted maxillary arch by means of an automatic, standardized speech recognition system.

MATERIALS AND METHODS

The speech intelligibility of 45 patients with complete tooth loss or a loss including missing anterior teeth in the maxilla was evaluated by means of a polyphone-based automatic speech recognition system that assessed the percentage of correctly recognized words (word accuracy). To replace inadequate maxillary removable dentures, 20 patients from the overall sample had been rehabilitated with complete dentures and 25 patients with telescopic prostheses. Speech recordings were made in four recording sessions (with and without existing prostheses and then at 1 week and 6 months after placement of newly fabricated prostheses).

RESULTS

Significantly higher speech intelligibility was observed in both patient groups compared to the original results without the dentures inserted. After 6 months of adaptation, both groups had reached a level of speech quality that was comparable to the healthy control group. However, patients receiving new telescopic prostheses showed significantly higher levels of speech intelligibility compared to those receiving new complete dentures. Within 6 months, speech intelligibility did not significantly improve from the level found 1 week after insertion of new prostheses for both groups.

CONCLUSION

Patients benefit from the fabrication of new dentures in terms of speech intelligibility, regardless of the type of prosthesis. However, telescopic crown prostheses yield significantly better speech quality compared to complete dentures.

A follow-up study on removable partial dentures in undergraduate program: part I. participants and denture use by telephone survey

The aim of this study was to investigate the clinical outcome of removable partial dentures (RPDs) designed to minimize denture mobility during function. Using archived files of the undergraduate program between 2003 and 2005 at Tokyo Medical and Dental University, a list of 169 patients treated with 184 RPDs was created. The RPDs had either an acrylic resin-base or a cobalt-chrome framework-base. Two examiners telephoned all the listed patients and interviewed 118 patients (70%) regarding the use of their RPDs. Of 118 patients, 42 (36%) had stopped using, mainly due to problems with abutment teeth in resin-based dentures, and replacement in cobalt-chrome-based dentures. There was no significant difference in mean age, gender distribution, mean number of remaining/abutment teeth, distribution of denture arch, and Kennedy classification between denture use and nonuse groups (p>0.05). The nonuse group showed a significantly higher percentage of resin-base compared to the use group (p = 0.006). Logistic regression analysis indicated that resin-base was a significant risk factor for nonuse (p = 0.008). The present findings suggest that abutment teeth should be selected carefully, especially in this type of resin-based RPDs, and that the denture base material may be a critical factor which determines denture use.

Periapical and endodontic status of type 2 diabetic patients in Catalonia, Spain: a cross-sectional study

INTRODUCTION

The aim of this study was to investigate radiographically the prevalence of apical periodontitis (AP) and endodontic treatment in a sample of adult type II diabetic patients and control subjects.

METHODS

In a cross-sectional study, the radiographic records of 50 adult patients reporting a history of well-controlled type 2 diabetes mellitus (DM) (study group) and 50 age- and sex-matched subjects who reported no history of DM (control group) were examined. Periapical status of all teeth was assessed using the periapical index score.

RESULTS

The average number of teeth per patient in the diabetic and control groups was 21.9 and 24.6 teeth, respectively (P = .012). AP in one or more teeth was found in 37 diabetic patients (74%) and in 21 control subjects (42%) (odds ratio = 3.9, P = .002). One or more root-filled teeth were found in 35 (70%) and 25 (50%) of diabetic and control subjects, respectively (odds ratio = 2.3, P = .043). Among diabetic patients with root-filled teeth, 16 (46%) had AP affecting at least one treated tooth. Among controls with root-filled teeth, 6 (24%) had AP affecting at least one treated tooth (P > .05). Adjusting for teeth number, multivariate logistic regression analysis showed that periapical status (odds ratio = 3.3, P = .0071) and the number of root-filled teeth (odds ratio = 1.7; P = .0035) were significantly associated with diabetic status.

CONCLUSIONS

The results showed that in adult patients, type 2 DM is significantly associated with an increased prevalence of AP and endodontic treatment.

Postmenopausal osteoporosis and tooth loss

OBJECTIVE

The aim of this study was to determine relation between tooth loss and general body bone mineral density in postmenopausal female who were seeking for prosthetic treatment.

MATERIAL AND METHODS

There were included 79 women in this study (age from 49-81 years, mean age 62.9 years) with partial tooth loss. For all patients bone mineral density measurements for lumbar spine and both femoral necks by dual energy X-ray absorptiometry (Lunar DEXA DPX-NT, GE Medical Systems) were performed. Based on DEXA results patients were divided into 3 groups: normal bone density (T-score ≥-1.0), osteopenia (T-score from -1.0 till -2.5) and osteoporosis (T-score ≤-2.5). Dental investigation was performed to detect existing teeth. ANOVA analysis of variance was used to determine relationship between different variables by group. To test correlation between different values Pearson correlation was used.

RESULTS

The number of teeth in different bone mineral density groups is almost similar. There are no statistically significant differences between groups according the number of the all teeth present and according the number of teeth in maxilla and mandible. There is no significant correlation between the number of the teeth and DEXA readings, except there is weak correlation between the number of maxillary posterior teeth and bone mineral density in femoral neck.

CONCLUSION

There is no correlation between number of the teeth and general bone mineral density.

Dental functional status in a southern vietnamese adult population-a combined quantitative and qualitative classification system analysis

PURPOSE

The aim of this study was to explore the dental functional status of a Southern Vietnamese adult population using a new quantitative- and qualitative-based classification system.

MATERIALS AND METHODS

The sample consisted of 2,809 dentate subjects aged ⋝ 20 years from urban and rural areas of Southern Vietnam. Dentitions were classified by a dichotomized five-level step-by-step branching hierarchy reflecting functionality. Cut-offs were as follows: level I (dentition level) = 1 tooth present in each arch, level II (arch level) = 10 teeth in each arch, level III (anterior region) = all 12 anterior teeth present, level IV (premolar region) = ⋝ 3 premolar posterior opposing pairs (POPs) present, and level V (molar region) = 1 molar POP bilaterally.

RESULTS

Of the 2,809 subjects, 44% met all criteria for a functional dentition and 16% met none. Of subjects meeting level II, 81% had a complete anterior region, 74% had a sufficient premolar region, and 66% had a sufficient molar region. For subjects not meeting level II, these figures were 9%, 15%, and 8%, respectively. For patients meeting level II who were between 20 and 35 years of age, a mean 29.2 ± 2.4 teeth and 7.9 ± 2.1 POPs were present; subjects 65 years of age and older had a mean 25.6 ± 3.2 teeth and 5.9 ± 2.1 POPs. For patients not meeting level II, these numbers were 18.6 ± 2.9 teeth and 3.1 ± 1.8 POPs and 12.8 ± 5.4 teeth and 0.9 ± 1.4 POPs for 20- to 35-year-olds and those 65 years of age and older, respectively. Intraclass correlation coefficients for number of teeth and POPs showed fair to good group homogeneities.

CONCLUSIONS

The World Health Organization goal of retaining at least 20 teeth throughout life is not achieved in Southern Vietnam; above the age of 44, less than 75% of subjects presented with 20 or more teeth. The presented classification system is a useful framework for mapping the functionality of dentitions by applying additional criteria for dental regions.

Evaluation of senior Brazilian dental students about mouth preparation and removable partial denture design

This study aimed to evaluate the knowledge of senior dental students about mouth preparation and removable partial denture (RPD) design. Two hundred sixty-six senior students from eleven dental schools in the State of São Paulo, Brazil, comprised the sample. The subjects examined two partially edentulous casts mounted on a semiadjustable articulator, answered a questionnaire regarding the treatment plan, and drew the RPD design. The casts consisted of Kennedy Class III, modification 1 maxillary arch and Class II mandibular arch. Ninety percent of the students believed that mouth preparation should be performed although no one was able to name all necessary procedures. For the maxillary arch, 12 percent of the denture designs were completely appropriate, 51 percent were partially appropriate, and 37 percent were inappropriate. For the mandibular arch, the results were 3 percent, 40 percent, and 57 percent, respectively.

Validation of the Eichner index in relation to occlusal force and masticatory performance

PURPOSE

Eichner Indices (A, B, and C), especially the Eichner subgroups (A1-A3, B1-B4, C1-C3), have not been validated in relation to oral functions. The purpose of this study was to investigate the association of posterior occlusal contact loss with occlusal force and masticatory performance in subjects who had a normal dentition or partially edentulous arches restored with removable prostheses.

MATERIALS AND METHODS

The study sample consisted of 1,288 independently living patients over the age of 60 years. Subjects were grouped into 10 subgroups by posterior occlusal contacts according to the Eichner Index. Bilateral maximum occlusal force in the intercuspal position was measured using pressure-sensitive sheets. Masticatory performance was determined by the concentration of dissolved glucose obtained from comminuted gummy jellies.

RESULTS

Occlusal force and masticatory performance were significantly associated with posterior occlusal contacts. Occlusal force measured in subgroups A2 to B2 and B3 to C3 did not differ statistically, although overall occlusal force decreased significantly as the loss of occlusal contacts increased. Similarly, masticatory performance was reduced with decreasing occlusal contact, although the decline was more gradual. Masticatory performance among subgroups A1 to B1, A3 to B2, B2 to B3, B4 to C2, and C1 to C3 did not differ significantly.

CONCLUSIONS

The Eichner Index subgroups were significantly associated with reduced oral functions, even if the teeth were restored with removable prostheses. Preservation of occlusal contacts of the bilateral (B2) and unilateral (B3) premolars was critical for occlusal force and masticatory performance, respectively.

Longevity of frictional telescopic crowns in the severely reduced dentition: 3-year results of a longitudinal prospective clinical study

OBJECTIVES

The longevity of frictional telescopic crowns (FTC) in severely reduced dentitions with 1 to 3 remaining teeth per jaw has not yet been studied prospectively and exclusively. Aims of this study were to estimate risks of telescope loss and abutment tooth loss and to determine abutment tooth mobility over time.

METHOD AND MATERIALS

A total of 74 patients with severely reduced dentitions received 82 telescopic removable partial dentures (TRPDs) retained with 173 FTCs. Dentures were reexamined after 1 week and 3, 6, 12, 18, 24, 30, and 36 months. Tooth mobility was monitored with Periotest values. Adjuvant therapies were carried out if necessary. Survival probabilities of telescopes and abutment teeth as well as the influence of clinical factors (age, sex, jaw, vitality, opposing dentition, axis inclination, end Periotest value, crown length, crown margin quality, wearing mode, tooth types, abutment distribution, number of telescopes) were calculated with Kaplan-Meier estimators. The relative risks for telescope loss were calculated with Cox regression.

RESULTS

The survival rate was 93.9% for abutment teeth and 87.5% for telescopes. Number of telescopes, abutment distribution, vitality, and gender as factors influenced the survival rates (Kaplan-Meier). In combination with the jaw as a factor, these affected the risk for telescope loss (Cox regression). Periotest values (mean of abutment teeth per examination) decreased significantly (P < .0001). Altogether, 11% of teeth fractured and 4.6% of teeth were extracted. Patients were mostly very satisfied.

CONCLUSION

TRPDs proved to be a favorable treatment concept for severely reduced dentitions. FTCs can be considered as elements with a good benefit-maintenance relation. A general increase of abutment tooth mobility could not be verified.

Degenerative changes in human temporomandibular joints in relation to occlusal support

OBJECTIVE

Controversy exists concerning the etiological factors behind degenerative changes in the temporomandibular joints (TMJs). Tooth attrition, occlusal support, food consistency, ageing, gender and genetics are some possible causative factors that have been discussed in the literature. The aim of this study was to examine contemporary human skull material for possible relations between degenerative form and surface changes in the TMJs in relation to occlusal support.

MATERIAL AND METHODS

The material consisted of 259 human skulls from 170 males and 89 females, with an age range of 18-100 years.

RESULTS

Dental status was in general poor, and 22% of skulls were edentulous. Form and surface changes of both the condyles and the temporal components were more common in the present material compared to that in most previous studies. In males, irrespective of age, only weak and clinically insignificant correlations could be found between degenerative TMJ changes and occlusal support. In women, however, the correlations between these variables were in general much stronger, especially at higher ages.

CONCLUSIONS

The present findings do not lend support to the hypothesis that loss of occlusal support is a causative factor for degenerative changes in the TMJs in male subjects. In women, such a correlation was obvious in the present sample, at least at higher ages. It can be speculated that hormonal factors play a role in the sex difference found.

Comprehensive implant restoration and the shortened dental arch

The restoration of edentulous space or hopeless teeth with implant-supported restorations can involve extensive time, effort, and financial commitment. This article presents a case of a debilitated dentition that was restored by using the shortened dental arch (SDA) concept in a comprehensive implant restoration. An SDA design was used to replace removable partial dentures with multiple nonsplinted implant-supported crowns extending to the premolars. The results showed an immediate and dramatic improvement in comfort, function, and esthetics while allowing the patient to practice normal oral hygiene.

Morphologic classification and stress analysis of the mandibular bone in the premolar region for implant placement

PURPOSE

The objective of this study was to assess the influence of mandibular morphology on the stress and strain distributions in the bone supporting an implant.

MATERIALS AND METHODS

Subjects were selected from patients with missing mandibular premolar teeth. Computed tomographic scans of the premolar region were classified into nine groups based on the overall bone morphology and the relative position of the alveolar crest. Finite element models of the bone on the basis of this classification, with inserted implants and superstructures, were constructed. A load of 200 N applied 30 degrees buccal from the vertical axis was directed toward the occlusal surface.

RESULTS

One hundred two partially (n = 98) and completely (n = 4) edentulous subjects were recruited. Their ages ranged from 40 to 79 years (mean age, 60.5 years; 41 men and 61 women). Approximately 56% of the patients showed bone widening in the caudal direction. The maximum compressive stresses were shown in the lingual cervical regions. An influence of overall bone morphology on stress distribution was not observed; however, the alveolar crest contour clearly affected the maximum stress and strain values. Compressive microstrain above 4,000 was observed only when the alveolar crest was lingually located relative to the body of the mandible. These high strain levels were concentrated at the lingual cervical margin, with volumes ranging from 0.04 to 0.07 mm3.

CONCLUSION

The contour of the alveolar crest potentially plays a critical role in maintaining the bone levels surrounding implants.

Oral health and its influence on cognitive behavioral therapy in patients fulfilling the Diagnostic and Statistical Manual of Mental Disorders-IV criteria for intra-oral injection phobia

OBJECTIVE

To describe self-perceived and clinically assessed oral health and oral treatment needs among intra-oral injection-phobic patients (Diagnostic and Statistical Manual of Mental Disorders-IV) and to explore whether these factors have an impact on the outcome of cognitive behavioral therapy (CBT).

MATERIAL AND METHODS

Fifty-five patients (43 women, mean age 32.5 years, range 18-62 years) were treated with short-duration CBT. Dental anxiety (Dental Anxiety Scale and Dental Fear Survey) and self-perceived oral health were assessed by means of questionnaires. Three dentists assessed oral health by means of clinical examination and radiographs. Treatment outcome was measured by ability to receive an intra-oral injection by a general dentist within a 1-year follow-up (FU) period or ability to complete a behavioral avoidance test (BAT) at FU, and changes in dental anxiety and positive and negative thoughts from pretreatment to FU.

RESULTS

Forty percent of patients ranged their oral health as "good" or "very good". Mean decayed teeth (DT) was 2.2 (range 0-15). The total number of teeth in need of treatment, periodontal treatment, endodontic treatment and extractions ranged from 0 to 15, 0 to 19, 0 to 4 and 0 to 5, respectively. Self-rated oral health correlated significantly with clinical oral health. The outcome of CBT in terms of being able to receive a dental injection during FU was not influenced by oral health status. However, correlation analyses indicated that patients with the poorest oral health had the greatest increase in positive thoughts and the greatest decrease in negative thoughts from pretreatment to FU.

CONCLUSIONS

The oral health of intra-oral injection-phobic patients varies substantially, but is comparable to that of the normal population. Coping with a dental injection after CBT is not influenced by oral health and treatment needs.

Decision making among Swedish general dental practitioners concerning prosthodontic treatment planning in a shortened dental arch

The purposes of this study were to describe how dentists evaluated the importance of various patient-related items when planning for a treatment in a shortened dental arch, to analyse common dimensions of the decision-making in comparison to other decision situations, and to identify explanatory factors behind these dimensions. A questionnaire containing different statements regarding the shortened dental arch concept was sent to a random sample of Swedish general dentists (n=189), with a response rate of 54%. The dentists were asked to evaluate items to be considered when planning for a prosthetic treatment in a shortened dental arch. Differences between individuals were great as well as between groups of dentists. Especially delivery system but also place of dental education and attitudinal factors were related to the shortened dental arch decision making process.

Removable partial dentures

On one side, prosthodontic reconstructions compensate for the sequelae of negative changes in the oral cavity; on the other side, they often enhance or accelerate them. As a consequence of negative changes in the oral cavity over time, treatment planning for RPDs becomes highly complex. A set of reliable criteria is necessary for decision-making and problem management It appears that the majority of published data on RPDs does not depict high effectiveness of this treatment modality. From a strict point of view of evidence-based dentistry, the level of evidence is low if not missing for RPDs. Randomized controlled trials on RPDs are difficult to design, they are not feasible for some questions due to the complexity of the material, or may remain without clinical relevance. The literature rarely gives information on the denture design, tooth selection, and management of the compromised structural integrity of teeth. So far treatment outcomes with RPDs must be considered under the aspect of bias due to the bias in indication and patient selection for RPDs. Better clinical models should be elaborated with more stringent concepts for providing RPDs. This encompasses: risk analysis and patient assessment, proper indications for maintenance or extraction of teeth, strategic placement of implants, biomechanical aspects, materials, and technology. Although there is a tendency to offer fixed prostheses to our patients, this might change again with demographic changes and with an increase in the ageing population, an increase in their reduced dentition, and low socioeconomic wealth in large parts of the world.

Osseointegrated implants as orthodontic anchorage and restorative abutments in the treatment of partially edentulous adult patients

One of the main limitations of orthodontic treatment in partially edentulous patients is the lack of anchorage to obtain desirable tooth movement. Coordination between the orthodontist, periodontist, and restorative practitioner is essential when planning treatment for these patients. Implants can be used not only in the definitive prosthetic solution but can also be of great benefit as stable abutments during orthodontic therapy. For ideal results, it is essential to establish an orthodontically favorable position for an implant and, more importantly, the best position for an adequate restoration following orthodontic treatment. The aim of this article is to demonstrate the use of implants in orthodontic movement to provide easier and more predictable restorative treatment.

Impacts of toothbrushing frequency on periodontal findings in a group of elderly Lithuanians

PURPOSE

The aim of this study was to evaluate the severity of the findings of dental plaque, calculus and deepened periodontal pockets in relation to self-reported toothbrushing frequency in a group of elderly Lithuanians. The authors hypothesised that those reporting twice daily toothbrushing exhibit less severe periodontal findings.

MATERIALS AND METHODS

A cross-sectional study of 94 dentate patients aged 60 or older was conducted at two public dental offices in Lithuania. Half-mouth recordings of dental plaque, calculus and deepened periodontal pockets were expressed as mean values per subject. These indicators described the severity of periodontal findings. A self-administered questionnaire provided information on toothbrushing frequency, age, gender and education. Statistical evaluation included chi-square test, analysis of variance and logistic regression.

RESULTS

None of the subjects were plaque-, calculus- or pocket-free. Of all, 26% reported that they brushed their teeth at least twice daily, 36% once daily and 38% less frequently. Women (P = 0.004), younger (P = 0.002) and higher educated respondents (P < 0.001) reported twice daily toothbrushing more frequently than did their counterparts. Twice daily toothbrushing was clearly associated with the least severe conditions regarding dental plaque (P = 0.03) and deepened pockets (P < 0.001), but not calculus (P = 0.39). Logistic regression models revealed higher level of education as the strongest factor odds ratio (OR = 2.7; P = 0.04) explaining the lowest scores of dental plaque. Higher frequency of toothbrushing was the strongest factor (OR = 2.1; P = 0.03) to explain the lowest scores of deepened periodontal pockets.

CONCLUSION

Twice daily toothbrushing contributes to better periodontal health in the elderly subjects and should be encouraged at every dental appointment.

Effect of implant support on distal-extension removable partial dentures: in vivo assessment

PURPOSE

The use of a limited number of implants for support of a removable partial denture (RPD) changes a Kennedy Class I or II situation to that of a Class III. This in vivo pilot study evaluated implant-supported distal-extension removable partial dentures (RPD) in 5 partially edentulous patients.

MATERIALS AND METHODS

Two implants (Brånemark TU MK III, Nobel Biocare) were placed in a mandibular Kennedy Class I arch. To fabricate an implant-supported RPD (ISRPD), a conventional RPD base was fitted to the healing abutment with autopolymerizing acrylic resin (Uni-fast II, GC) to support the posterior aspect of the RPD. By changing the healing abutment to a healing cap, there was no connection between the denture base and implant, and the ISRPD became a conventional RPD (CRPD). Using a crossover study design, the masticatory movements (mandibular movements during mastication) of both dentures were measured using a commercially available tracking device (BioPACK, Bioresearch, Japan). The occlusal force and contact area were also measured using pressure-sensitive sheets and an image scanner (T-scan system). Using a visual analog scale (VAS), the 4 criteria of comfort, chewing, retention, and stability were evaluated. All the data obtained were analyzed using Wilcoxen signed rank tests (alpha = .05).

RESULTS

There were no significant differences (P > .05) in masticatory movements between the ISRPD and the CRPD (5 patients: 4 women, 1 man). However, the ISRPD had significantly greater force and greater area than the CRPD (P = .043). The center of occlusal force of the ISRPD tended to move more distally compared to the CRPD. All the patients preferred the ISRPD for comfort, chewing, retention, and stability.

CONCLUSIONS

One implant per edentulous area and a simple attachment technique yielded a stable distal extension RPD.

The single-tooth dental implant: practical guidelines for hard tissue augmentation

With the increased popularity of implants and focus on .. esthetics, there is great emphasis on idealized bone foundation and soft tissue contours. The goal of reconstructive procedures is to provide peri-implant bone that support and maintain gingival contours. This article reviews ridge deficiency diagnosis and predicts the need for bone augmentation before tooth extraction. It also presents early intervention to minimize bone loss, various bone reconstruction techniques, and suggests predictable methods for different clinical scenarios.

An audit of letters of referral to a prosthodontic department in a dental teaching hospital

The purpose of this study was to investigate the quality and number of letters of referral for new patients received in the Prosthodontics Department of a Dental Teaching Hospital. Letters received during the month of May 2006 were included. Each letter of referral was tested against five criteria which might be expected in an appropriate letter of referral. These were information on the following: relevant dental history, relevant medical history, teeth present, diagnosis, and treatment plan. The results showed that only 8% of letters met all five criteria and 11% met none of them. Letters requesting better information were sent to referring practitioner as a result of this audit. However a re-audit in May 2007 showed that 9% of letters met all five criteria and 15% met none of them. A need has been identifiedfor better referral letters and ways of achieving this were discussed.

The relationship between missing occlusal units and oral health-related quality of life in patients with shortened dental arches

This study aimed to investigate the relationship between missing occlusal units and oral health-related quality of life (OHRQoL) in subjects with shortened dental arches (SDAs). Subjects with SDAs (N = 115) were recruited consecutively from 6 university-based prosthodontic clinics. OHRQoL was measured using the Japanese version of the Oral Health Impact Profile (OHIP-J). An increase of 1 missing occlusal unit was associated with an increase of 2.1 OHIP-J units (95% CI: 0.6-3.5, P = .02) in a linear regression analysis. Missing occlusal units are related to OHRQoL impairment in subjects with SDAs.

Factors related to patients' general satisfaction with removable partial dentures: a stepwise multiple regression analysis

This study aimed to analyze factors related to patients' general satisfaction with removable partial dentures (RPDs), such as esthetics, retention, speech, chewing, and comfort. A total of 103 patients with Kennedy Class I RPDs (34 to 82 years old; mean age: 63; 35 men, 68 women) assessed their satisfaction with dentures. Stepwise multiple regression analysis was used to evaluate the relationship among the factors. Significant correlations were found between general satisfaction and each of the individual components (P < .05). The patients' assessment of esthetics explained almost 50% of general satisfaction in both arches (P < .05). Esthetics, chewing, and speech had significant effects on the patients' general satisfaction with dentures.

Combination syndrome: classification and case report

Combination syndrome (CS) is a dental condition that is commonly seen in patients with a completely edentulous maxilla and partially edentulous mandible with preserved anterior teeth. This syndrome consists of severe anterior maxillary resorption combined with hypertrophic and atrophic changes in different quadrants of maxilla and mandible. This makes it a challenging condition in dentistry that requires significant experience along with advanced restorative and surgical skills. The causes of maxillary bone resorption and ways to correct it are discussed in this article. Conventional treatment with full upper and partial lower dentures for the CS patients is not always adequate or satisfying for patients and it often requires multiple remakes due to continuing bone resorption. Dental implant rehabilitation challenges conventional treatment with bone-anchoring techniques to provide improved retention and stability for implant-retained and supported prostheses. This article presents a successful implant treatment of the partially edentulous maxilla in CS patient. The author proposes a new classification of the combination syndrome that includes a multitude of CS cases with partial and complete maxillary and mandibular edentulism. The necessity of a multi-disciplinary approach for early prevention and treatment of this complex condition is emphasized.

Implants in conjunction with removable partial dentures: a literature review

Although the benefits of implant-borne removable prostheses are readily apparent for the fully edentulous patient and have been well documented, there is a paucity of studies concerning the combination of implants with removable partial dentures in partially edentulous patients. The aim of this article is to review the literature regarding implants with removable partial dentures and evaluate the evidence for this clinical approach. A MEDLINE/PubMed search from 1990 to 2006, focusing on the use of implants with removable partial dentures and related features, was supplemented with a hand search to identify relevant peer-reviewed English articles published in dental journals and textbooks on removable partial dentures.

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.

Impact of local and systemic factors on the incidence of oral implant failures, up to abutment connection

AIM

The aim of this retrospective study was to assess the influence of systemic and local bone and intra-oral factors on the occurrence of early implant failures, i.e. up to the abutment connection.

MATERIAL AND METHODS

The surgical records of 2004 consecutive patients from the total patient population who had been treated in the period 1982-2003 (with a total of 6946 Brånemark system implants) at the Department of Periodontology of the Catholic University Leuven were evaluated. For each patient the medical history was carefully checked. Data collection and analysis mainly focused on endogenous factors such as hypertension, coagulation problems, osteoporosis, hypo-hyperthyroidy, chemotherapy, diabetes type I or II, Crohn's disease, some local factors [e.g. bone quality and quantity, implant (length, diameter, location), type of edentulism, Periotest value at implant insertion, radiotherapy], smoking habits and breach of sterility during surgery.

RESULTS

A global failure rate of 3.6% was recorded. Osteoporosis, Crohn's disease, smoking habits, implant (length, diameter and location) and vicinity with the natural dentition were all significantly associated with early implant failures (p<0.05).

CONCLUSION

The indication for the use of oral implants should sometimes be reconsidered when alternative prosthetic treatments are available in the presence of possibly interfering systemic or local factors.

Masticatory performance in postmaxillectomy patients with edentulous maxillae fitted with obturator prostheses

PURPOSE

Oral cancer develops frequently in older populations. In Japan, the incidence of oral and pharyngeal cancer is 9,201 per year, with such tumors accounting for 1.74% of all cancers. Although obturator prostheses play an important role in the rehabilitation of postmaxillectomy patients, clinicians sometimes experience difficulty in placing obturator prostheses in edentulous maxillae, and criteria for the objective evaluation of treatment outcome have yet to be established. The present study aimed to investigate postsurgical factors influencing the masticatory performance of postmaxillectomy patients with edentulous maxillae fitted with obturator prostheses.

MATERIALS AND METHODS

The extent of the hard palate defect, status of the mandibular dentition, mouth-opening distance, and maximum occlusal force were investigated, and masticatory performance was measured using a testing gummy jelly in 27 postmaxillectomy patients with edentulous maxillae fitted with obturator prostheses. The influence of these items was evaluated quantitatively, and theoretical masticatory performance for each subject was calculated using multiple-regression analysis (quantification method type 1).

RESULTS

Although average masticatory performance was almost equivalent to that of healthy, independent older patients with occlusal support classified as Eichner C, considerable individual variation was noted among subjects. The order of strength of influence on masticatory performance was identified by category weight: extent of hard palate defect > status of posterior mandibular teeth > maximum occlusal force > mouth-opening distance. A relatively high correlation (R2 = 0.78, P < .01, Pearson correlation coefficient) was evident between theoretical and actual values.

CONCLUSION

Masticatory performance could be predicted by evaluating postsurgical factors in patients with edentulous maxillae fitted with obturator prostheses.

Linguistic adaptation and validation of the General Oral Health Assessment Index (GOHAI) in an elderly Japanese population

OBJECTIVES

This study sought to develop a Japanese version of the General Oral Health Assessment Index (GOHAI) and validate its use in an elderly Japanese population.

METHODS

The GOHAI scale was translated in a standardized way consisting of forward translation, pilot study, and backward translation. Psychometric properties of the final version were assessed on 175 participants (mean age: 70.0 years, SD 6.4).

RESULTS

The response rate was more than 98% for each item. The reliability in terms of a Cronbach's alpha value was 0.89. The mean GOHAI scores were significantly lower for participants with poor perceived oral health (P<0. 001) or poor perceived general health (P<0.01). Significant correlations were observed between the GOHAI scores and the general health or physical functioning scores of the Medical Outcome Study Short Form 36 (P<0.01).

CONCLUSIONS

The present study showed that the Japanese version of the GOHAI was psychometrically valid in an elderly sample population.

Partial edentulism and removable denture construction: a frequency study in Jordanians

This study aimed to investigate the frequency of different classes of patterns of partial edentulism and the most frequently used design components of conventional cobalt-chromium RPD constructed for patients attending a dental teaching hospital in Jordan. Two- hundred laboratory authorization forms were reviewed. Of the total 200 patients (150 male, 48 females, mean age 44.5 years), 150 patients had both maxillary and mandibular Co-Cr RPDs constructed with a total number of frameworks sums to 350. Kennedy classification was followed to identify the class of partial edentulism. Of the total 350 patterns, Kennedy class III was the most common classification encountered in maxilla (47%) and in the mandible (45%). Among combinations, maxillary Kennedy class III classification opposing mandibular class III was the most common combination (30%). The lingual bar was the most frequently designed major connector (77%), while palatal strap was the most common connector in the maxilla (38%). Significantly (p<0.05), patterns with Kennedy class II and III were more frequent among males than females. The most common type of direct retainer used was the circumferential clasp in both maxillary and mandibular RPD's. On the other hand, ring clasps were used three times more frequently in mandibular RPD frameworks compared to maxillary RPD's. The RPI clasp assembly was used in class I and class II situations in 75% of cases more common in the mandible. It is concluded that the variations in construction of RPD design concepts with international studies reflects the influence of teaching philosophy and diversity of faculty members' backgrounds.