Subjective and Objective Assessment of Chewing Performance in Older Adults with Different Dental Occlusion.

OBJECTIVES: Satisfactory masticatory function is a significant indicator of improved oral health-related quality of life in older adults, either with or without artificial teeth. The purpose of this study was to examine masticatory performance of older adults with different prosthodontic reconstructions and occlusion, as well as to compare subjective and objective assessment of chewing performance. MATERIAL AND METHODS: This study included 100 participants aged 65 and more. The chewing function questionnaire (CFQ) with answers on the Likert scale 0-4 (0 = no difficulties; 4 = maximum difficulties) was used as an indicator of subjective masticatory assessment. The two-color chewing gum test was used as objective assessment of masticatory function (mixing ability), based on the Z-score values. Dental occlusion was assessed using functional teeth units (FTU). RESULTS: The results obtained using the CFQ and the clinical mixing ability test are in compliance with each other (r = 0.742). A decrease in the number of natural teeth, especially posterior teeth, progressively reduced chewing ability and increased difficulties in mastication. Participants with less FTUs, or with FTUs that are a part of removable denture, had greater reduction in masticatory function compared to those with FTUs composed of natural teeth or fixed partial dentures. CONCLUSION: This study revealed a strong positive correlation between the subjective masticatory assessment in older adults using the validated questionnaire and the objective clinical test of the mixing ability of two chewing gums. Our data on influence of the number and the type of FTU on masticatory performance will be valuable when planning prosthodontic therapy.

Study on the surface properties of different commercially available CAD/CAM materials for implant-supported restorations.

OBJECTIVE: To determine if there are any differences in surface characteristics (surface roughness and contact angle) among different CAD/CAM materials indicated for fabricating implant-supported restorations, following all the material preparation protocols provided by the manufacturer. MATERIALS AND METHODS: One-hundred forty-four specimens were divided into six groups: RBC (resin-based composite), PMMA (polymethyl methacrylate), PEEK (polyether ether ketone), ZP (zirconia polished), ZG (zirconia glazed) and CoCr4 (CoCr4 alloy). The experimental part included surface roughness (SR) and contact angle of water (WCA) analyses, fulfilled with Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) view of surface topography. The data were analyzed using Kruskal-Wallis test with a Dunn's post hoc analysis, the correlation between measurements was tested using Spearman's rank correlation coefficient and all data were presented as mean ± SD. RESULTS: ZG specimens were significantly rougher compared to other groups (p ≤ 0.05). The WCA measurements revealed significantly lower mean values in ZG group (p ≤ 0.05), contrary to PEEK and CoCr4 , where significantly higher mean values were observed, compared to other groups (p ≤ 0.05). There exist a moderate negative correlation between the SR and WCA (ρ = -0.41). AFM 3D and SEM 2D images presented more or less heterogeneous surface of all materials. CONCLUSIONS: There were statistically significant differences in surface roughness and contact angle among tested material groups. Moderate negative correlation was found between surface roughness and contact angle of tested material groups. CLINICAL SIGNIFICANCE: The study gives us a better understanding of influence of physicochemical characteristics of investigated materials on their surface properties and provides useful knowledge for future researches in a view of material's behavior under in vivo conditions, when it comes to a question of features related to surface quality, such as microbial adhesion, corrosion, wear, biocompatibility and esthetics.

Translation and preliminary validation of the Serbian version of an ageism scale for dental students (ASDS-Serb).

AIMS: The ageist attitudes among dental clinicians may result in inadequate treatment planning and reduce quality of life for older adults. This study aimed at performing a preliminary validation of an ageism scale for dental students (ASDS) in Serbia (ASDS-Serb). METHODS AND RESULTS: The 27-item ASDS was translated from English into Serbian and completed by 129 dental students. Principal component analysis (PCA), Confirmatory factor analysis (CFA), internal consistency reliability and discriminant validity were estimated. PCA produced a 17-item scale distributed into five factors that explain 64.24% of the total variance. All items showed high to moderate reliability (0.50-0.83). CFA indicates an acceptable model fit with significant standardized factor loadings ranging from 0.14-0.99. The first factor dealt with negative views of older adults' life and dental treatment, the second factor related to ethical values about older people, the third factor compared younger and older adults in dental care and the fourth factor related to difficulties in medical history taking. The fifth factor related to perceptions of oral health and treatment of older adults. Discriminant validity revealed significant differences related to the semester of studies, gender and having older people in the family. CONCLUSION: The preliminary validation of the ASDS-Serb resulted in a 17-item scale distributed into the five factors with acceptable validity and reliability.

Oral Health Status and Nutritional Habits as Predictors for Developing Alzheimer's Disease.

OBJECTIVE: Poor oral health, mainly tooth loss, has been suggested to pose a risk factor for Alzheimer's disease (AD). The nature of this relationship can be explained by mastication deficit and nutritional status. Also, the influence of nutritional parameters on cognitive impairment has been documented. The aim of this study was to investigate whether poor dental status and nutrition habits can be potential separate or associated risk factors for development of the AD. METHODS: The study sample included 116 patients with AD and 63 controls. Sociodemographic variables were investigated as factors potentially associated with AD. Dental examination included recording the number of natural teeth, presence of fixed or removable dentures, and the number of functional tooth units (FTUs). Nutritional status analysis included qualitative nutrition information, body mass index, serum albumin level, food consistency, and need for assistance in feeding. Regression analysis was used to investigate the predictors for development of AD. RESULTS: Variables with significant differences between groups, which were analyzed by using the binary regression analysis, were marital status, residence, number of total FTUs (no matter whether the contacts were between natural teeth or dentures), eating meat/fish and fruits/vegetables, food consistency, and serum albumin level. Logistic regression analysis showed that being single/widowed/divorced, eating more meat/fish or fruit/vegetable, eating blended/mashed/liquid food, having low levels of serum albumin, and having less FTUs were significant predictors for developing dementia. CONCLUSION: Having fewer occlusal contacts, consumption of soft food, and lower serum albumin levels can be considered as associated risk factors for AD.

Apolipoprotein ɛ4 Allele and Dental Occlusion Deficiency as Risk Factors for Alzheimer's Disease.

Compromised dentition has been suggested to pose a significant risk factor for dementia. It was mainly investigated through insufficient tooth number, disregarding contact between opposing teeth (dental occlusion). The ɛ4 allele of apolipoprotein (APOE4) is the primary genetic marker for the late onset of Alzheimer's disease (AD). However, APOE4 and dental occlusion have not yet been investigated as possible associated risk factors for AD. The study was aimed to examine the impact of dental status and different APOE gene variants on AD occurrence. Secondly, sociodemographic variables were investigated as factors potentially associated with AD. The case-control study included two groups: 116 patients with AD (according to the NINDS-ADRDA criteria) and 63 controls (Mini-Mental State Examination scores ≥24). The analysis of APOE gene polymorphism was conducted through PCR reaction. Dental examination included recording of number of teeth, presence of fixed or removable dentures, and number of functional tooth units (FTU). Regression analysis was used to investigate the joint effect of the clinical and genetic variables on AD. Results showed that patients with AD were more often carriers of ɛ3/ɛ4 genotype and ɛ4 allele, had lower number of teeth and FTU, and were less likely to be married, live in home, and had less chronic diseases, compared to the controls. Regression analysis showed that presence of APOE4 allele and the number of total FTU remained associated with AD, even when adjusted for age, sex, and level of education. In conclusion, deficient dental occlusion and presence of APOE4 may independently increase risk for AD.

Psychometric Characteristics of the Croatian and the Serbian Versions of the Oral Health Impact Profile for Edentulous Subjects, with a Pilot Study on the Dimensionality.

INTRODUCTION: The aim was to adapt the Croatian and the Serbian versions of the Oral Health Impact Profile for the edentulous population (OHIP-EDENT-CRO and OHIP-EDENT-SRB). METHODS: The translation and cross-cultural adaptation were carried out in accordance with accepted international standards. A total of 95 and 177 removable denture wearers were recruited in Croatia and Serbia respectively. The reliability was evaluated by calculating Cronbach's alpha coefficient and by test-retest (30 participants in each country). The concurrent validity was determined by calculating the Spearman's rank coefficient between the OHIP-EDENT summary scores and one question related to removable denture satisfaction. Construct validity was determined by exploratory factor analysis (EFA). Responsiveness was determined by comparison of the OHIP-EDENT summary scores before and after dental implant placement to support mandibular overdentures (23 patients in Croatia, 21 in Serbia). RESULTS: Cronbach's alpha coefficient was 0.92 in Croatia and 0.87 in Serbia. The intraclass correlation coefficient was 0.98 in Croatia and 0.94 in Serbia. In Croatia the Spearman's correlation coefficient was -0.71 (p<0.001) and in Serbia -0.74 (p<0.001). Both confirmed concurrent validity. Construct validity was tested by EFA, which extracted four factors in each country, accounting for 66.59% of the variance in Croatia and 59.33% in Serbia. Responsiveness was confirmed in both countries by a significant OHIP-EDENT summary score reduction and a high standardised effect size (3.9 in Croatia, 1.53 in Serbia). CONCLUSION: The results prove that both instruments, the OHIP-EDENT-CRO and the OHIP-EDENT-SRB, have very good psychometric properties for assessing OHRQoL in the edentulous population.

Self-perception and satisfaction with dental appearance and aesthetics with respect to patients' age, gender, and level of education.

Introduction: Patient's subjective evaluation of dental appearance and aesthetics is becoming an increasingly important factor in aesthetic treatments and prosthetic therapy. Objective: The aim of this study was to investigate the influence of age, education level, gender, and different dental status and the appearance of the upper anterior teeth (color, size, shape, position and alignment of the anterior teeth) on the satisfaction of the respondents with dental appearance and aesthetics of their upper anterior teeth and their desire for improvement. Methods: The study encompassed 480 people aged 20 to 50 years with an average age of 30.84 years. There were 236 male and 244 female subjects. The respondents were interviewed using a questionnaire specially designed for the purpose of this research. For the study, the subjects were divided into the following three age groups: the younger age group (20­30 years of age), the middle age group (31­40 years of age), and the older age group (41­50 years of age). Results: The conducted study did not reveal statistical significance with respect to gender in any of the examined parameters (p > 0.05). A little more than one half of the respondents in each age group were satisfied with their dental appearance and aesthetics (60.3% of the respondents in the age group of 20­30 years, 55.7% in the age group of 31­40, and 53.7% in the age group of 41­50 years of age). Satisfaction with dental appearance and aesthetics increases linearly with the increase in the level of education and was the highest among the respondents with university degree (33.3%). Conclusion: Female respondents were more dissatisfied with their dental appearance and aesthetics as compared with male respondents, but the difference was found to be non-significant. Patients with higher education level were more satisfied with their dental appearance and aesthetics than those with lower education.

Caregivers' attitudes, knowledge and practices of oral care at nursing homes in Serbia.

Background/Aim: Within the elderly population, residents in nursing homes, there is a greather risk of caries, periodontal disease and teeth loss. Assistance of caregivers in maintaininig good oral hygiene besides improving oral health can improve of residents general health and the qulity of their lives. The aim of this study was to examine the attitudes of caregivers and knowledge about oral health, as well as the practice regarding oral care they apply at nursing homes in Serbia. Methods: The survey was conducted at the Gerontology Center Belgrade, consisting of four nursing homes located in the urban area. The study included 58 caregivers. They were contacted on working days, in all work shifts, during January, February and March of 2013. They were asked to fill in a self-administered questionnaire consisting of 26 closed-type questions. Results: The caregivers mostly considered that it was very important to take care of oral health of the residents, but 69% responded that the level of their oral health was low or very low. As the main barriers to oral hygiene maintenance, the caregivers indicated lack of time. The caregivers had more knowledge about periodontal disease than about the main cause of caries and its prevention. Formal medical education had the influence on the knowledge about oral diseases. Oral hygiene procedures carried out by the mayority of caregivers were denture cleaning and tooth brushing. Conclusion: The caregivers were aware of the limitations in everyday oral care of nursing homes residents in Serbia, although solving these problems requires the involvement of the entire public health service.

Analysis of abutment teeth in partially edentulous patients.

The aim of the study was to examine changes in the position of the abutment teeth (AT), size of undercuts for a denture clasp, as well as an existence of an adequate preparation of abutment teeth. A total of 156 casts of partially edentulous jaws, with 460 AT, were analyzed. The size of undercuts, a degree of abutment rotation, inclination and migration were measured using a dental parallelometer. The abutment teeth position was related to the level of occlusal plane in a dental articulator. Furthermore, the existence of an adequate preparation of abutment teeth, as well as a type of a denture and a type of a denture retention element were also considered. Analysis were carried out twice on casts made from a hard stone, the first time before the denture treatment had begun and the second time on the new casts obtained after new dentures had been delivered. The first analysis (prior dental treatment) revealed that a total of 33.9% of the analyzed AT were rotated, 31.3% were inclined, 12.1% had migrated, and 57.3% were elongated above the occlusal plane. On the casts obtained after the new dentures had been made, it was observed that none of the AT had an adequate preparation. Only 37.6% of all retention elements were located in adequate undercut positions on the AT. Upon the results of the present study a conclusion can be established that many abutment teeth are rotated, elongated, inclined, and migrated, which point to a requirement for AT preparation prior the manufacture of new denture; however none of the AT was adequately prepared considering insertion plane and many denture elements were located in an inadequate undercut size.

Impact of genes and proportional contribution of parental genotypes to inheritance of root yield and sugar content in diploid hybrids of sugar beet.

This paper analyzes the impact of genes and proportional contribution of parental genotypes on the inheritance of root yield and sugar content in diploid hybrids of sugar beet. The survey included two diploid male-sterile monogerm lines and three single (SC) male-sterile hybrids as maternal components, while three multigerm diploids were used as pollinators. The partitioning of genotypic variance into additive and dominant components was performed by half sibling (HS) and full sibling (FS) covariance. The proportional contribution of individual components of crossbreeding (lines, testers, and interactions) was exhibited in the expression of certain characteristics of F1 generation. Genotypic variance components showed a significant effect of nonadditive gene action (dominance) in the inheritance of root yield and sugar content, while the additive effect of genes was less significant. Maternal components had a greater proportional contribution to root yield, while lines, pollinators, and their interactions had an equal contribution to sugar content.

Prevalence, severity, and clinical determinants of oral impacts in older people in Bosnia and Herzegovina.

This study aimed to assess the prevalence and the severity of oral impacts and the relationships between oral health-related quality of life (OHRQoL) and clinical measures of oral function in a sample of older adults in Bosnia. The sample comprised 261 community-dwelling adults of ≥65 yr of age. Participants were randomly drawn from three senior day-centres for elderly people. Data were collected using clinical examination and a questionnaire. The OHRQoL was assessed through the Oral Impacts on Daily Performances (OIDP) measure, in terms of the prevalence, intensity, and extent of oral impacts. Overall, 55.2% reported at least one oral impact in the last 6 months. Difficulty eating (43.3%) and difficulty speaking (34.1%) were the most common impacts. These were also the most severely affected performances, while 'going out' and 'enjoying the contact of other people' were the least severe. A higher number of natural teeth, natural occluding pairs, and anterior and posterior occluding pairs were all significantly associated with a lower prevalence of oral impacts and correlated with the OIDP score, even after adjusting for sociodemographic factors. The prevalence of oral impacts was high and there was a strong and consistent association between OHRQoL and clinical dental indicators of function.

[Applicability of a Serbian version of the "Oral Impacts on Daily Performance (OIDP)" index--assessment of oral health-related quality of life].

BACKGROUND/AIM: The Oral Impacts on Daily Performance (OIDP) is a well-known psychometric test used internationally to assess the oral health-related quality of life. The interview and self-administrated questionnaire both assess the degree to which oral health problems have affected the life of the participants over the previous 6 months. The aim of this study was to translate the OIDP index into Serbian and to assess its reliability in practice as its initial verification in the Serbian speaking area. METHODS: Following an internationally established methods, the OIDP scale was translated using standardized methodology that consisted of forward translation, pilot study and backward translation. RESULTS: A pilot study was carried out with 44 respondents (24 males i 20 females) using a preliminar Serbian version of the OIDP index. All patients were aged over 65 years. A total of 68.2% of the participants replied that they had at least one OIDP impact on daily life in the past 6 months. These troubles were most prominent during eating (47.7%) and speaking (36.4%), but there is a little impact of troubles in the domain of psychosocial sphere. The corrected item-total correlation coefficients for all items were above the minimum recommended level of 0.20 for including an item in a scale. The standardized Cronbach's alpha coefficient was 0.75. CONCLUSION: Based on these results, we can conclude that this index is suitable for use in everyday practice in Serbian speaking area providing useful information required to assess oral health-related quality of life.

Analysis of the compressive strain below the removable and fixed prosthesis in the posterior mandible using a digital image correlation method.

It was the purpose of this study to determine and analyse strains in the bone of posterior mandible below the removable and fixed partial dentures using Digital Image Correlation Method. Dried mandible with shortened dental arch (Kennedy Class 1) was used in the experiment. The mandible model was prepared for accepting two types of restorations for bilaterally missing molars conventional therapy, and removable and fixed partial dentures were manufactured following standard prosthetic protocol. The models with prosthetic restorations placed in situ were subjected to loading of 50-300 N, and photographed using two digital cameras as part of the digital image correlation method equipment. Afterwards, the obtained data for strains within restored mandible during loading ciclus were analysed in the software Aramis and graphically presented. Percentage size of the mandible strains within the line section are from 0.14 to 0.19% for the removable partial denture experimental model and 0-0.14% for the fixed partial denture experimental model. The study has demonstrated that Digital Image Correlation method can be used to measure strain on the mandible surface and replacements during loading and that from biomechanical perspective both therapeutic modalities can be equally useful for the restoration of the mandible with bilaterally distal edentulous spaces.

Validity and reliability of the Oral Impacts on Daily Performance (OIDP) scale in the elderly population of Bosnia and Herzegovina.

OBJECTIVES: To adapt the Oral Impacts on Daily Performance (OIDP) index for elderly people in Bosnia and Herzegovina and test its validity, reliability and responsiveness to change. BACKGROUND: Clinical measures alone may not be adequate for assessing the oral health of individuals. Subjective oral health indicators tested within a particular cultural context may not be relevant across cultures. MATERIALS AND METHODS: The study population comprised 231 free-living adults aged 65 years or older. The OIDP was cross-culturally adapted from English into the Serbian language and its psychometric properties were tested. Data were collected using a clinical examination and a questionnaire containing the OIDP. RESULTS: In terms of reliability, Cronbach's alpha coefficient was 0.82 and the intraclass correlation coefficient 0.88. The very high correlation of OIDP with self-rated oral health (r = 0.78) verified criterion validity, while construct validity was demonstrated through its significant and graded associations with other subjective health measures. OIDP change scores on a treated subsample showed moderate effect size (0.59) and were associated with perceptions of oral health change, providing evidence for its responsiveness to change. CONCLUSION: The Bosnian version of the OIDP showed satisfactory validity, reliability and responsiveness to change confirming its appropriateness for use among older populations in Bosnia and Herzegovina.

[Comparative analysis of unilateral removable partial denture and classical removable partial denture by using finite element method].

INTRODUCTION: Various mobile devices are used in the therapy of unilateral free-end saddle. Unilateral dentures with precise connectivity elements are not used frequently. In this paper the problem of applying and functionality of unilateral free- end saddle denture without major connector was taken into consideration. OBJECTIVE: The aim was to analyze and compare a unilateral RPD (removable partial denture) and a classical RPD by calculating and analyzing stresses under different loads. METHODS: 3D models of unilateral removable partial denture and classical removable partial denture with casted clasps were made by using computer program CATIA V5 (abutment teeth, canine and first premolar, with crowns and abutment tissues were also made). The models were built in full-scale. Stress analyses for both models were performed by applying a force of 300 N on the second premolar, a force of 500 N on the first molar and a force of 700 N on the second molar. RESULTS: The Fault Model Extractor (FME) analysis and calculation showed the complete behaviour of unilateral removable partial denture and abutments (canine and first premolar), as well as the behaviour of RPD under identical loading conditions. Applied forces with extreme values caused high stress levels on both models and their abutments within physiological limits. CONCLUSION: Having analyzed stresses under same conditions, we concluded that the unilateral RPD and classical RPD have similar physiological values

[Adaptation of Oral Health Impact Profile (OHIP-14) index for measuring impact of oral health on quality of life in elderly to Serbian language].

BACKGROUND/AIM: There is an evidence of increasing necessity to use indices for measuring impact of oral health on the elderly life quality for the purposes of the state-of-the art clinical dental practice. It is at least because data obtained in that way suggest whether a treatment is required, help in deciding upon a kind of dental treatment, as well as in evaluating the extent of success of the applied therapeutical procedures. The aim of the study was to translate into Serbian the Oral Health Impact Profile-14 (OHIP-14) index and to assess its validity in practice as its initial verification in the Serbian speaking areas. METHODS: The OHIP-14 index was translated into Serbian and check-up of its easy-to-understand done in a group of 30 common elderly (above 65 years of age) with a total or partial prosthetic restoration. The study individuals did not fill in a questionnaire by themselves, instead the questiones were put orally. If needed, additional explanations were given with no any suggesting a possible answer. RESULTS: Considering the given answers and the shown need for additional explanations to some questions indicated that the question number 5 in the OHIP-14, namely "Have you been selfconscious because of your mouth or dentures?" (Serbian, "Da li ste bili samosvesni usled problema sa Vasim ustima i protezama?") cannot be adequately translated into Serbian because even 28 (93.3%) of the tested individuals were not able to understand it inspite the given explanations. Other questions were well understood, thus allowing to use the answers to them as score for a certain discomfort. Of all the tested, 13 (43%) denied any psychosocial disorders or experienced them only rarely, while 60% of the tested answered affirmately to the question "Do you consider your life generally less satisfactory due to the problems induced by teeth and dentures?" pointing out a significant impact of oral health condition on the quality of life. CONCLUSION: The OHIP-14 index renders valuable and dependable data on the quality of life of elderly with dentures, thus it is favorable to use it in practice. Due to difficulties in understanding the question number 5, however, it was ommited off the final Serbian language version. Anyhow, its validity in a more numerous test group should be evaluated, as well as other indices introduced into Serbian speaking area to let a comparison made and the most suitable questionnaire used.

Retention of telescopic denture in elderly patients with maximum partially edentulous arch.

UNLABELLED: The telescopic denture is one possible solution for prosthetic rehabilitation for a partially dentate arch with few remaining teeth, which is the reason why it is usually considered in elderly patients. The system of double crowns consists of the male component of attachment or patrix, which is cemented to the abutment tooth, and the female component of attachment or matrix, which is the removable part of the restoration. Retention force represents resistance to those forces which tend to separate the partial denture and supporting tissue in the occlusal direction. Its optimal value is 5-9 N per each patrix and it should strictly be between these limits as a stronger or weaker force will endanger the functionality of the denture or damage the supporting tissue of the abutment teeth. OBJECTIVE: The goal of this study was to establish the exact value of the individual and total retention force of the completed telescopic system. METHOD: The Bredent dynamometer was used for measuring these values. The study involved measuring the individual force of separation of 50 patrix-matrix components, and total force of 20 partial dentures of various designs retained by double crowns made in the Dental Laboratory of the Clinic for Prosthetic Dentistry, Faculty of Stomatology, Belgrade University. The research was carried out in the period from January 2006 to October 2006. RESULTS AND CONCLUSION: The results showed different values of separation force - from very low values to those exceeding optimal limits. A reduction in the force of separation is necessary in the case of excessive tightness. If there was looseness between patrix and matrix, the cylindrical components of double crowns need to be lined by a suitable composite material.

[Convenience of vestibular surfaces of lower canines for accepting retention elements of removable partial denture]. / Pogodnost vestibularnih povrsina donjih ocnjaka za prihvatanje retencionih elemenata parcijalne skeletirane proteze.

Lower canines often appear as abutment teeth of partially edentulous dental arch. Crown contours of these teeth are mostly inconvenient for placing clasps. The convex vestibular surfaces with sufficient undercuts for placing retention elements are obligatory on lower canines but it is not common case. Aim of this paper was to confirm a high frequency of unexistence of buccomesial and buccodistal undercuts of the lower canines. Measuring of buccomesial and buccodistal undercuts on abutment lower canines was preformed on 50 diagnostic casts of lower jaw, belonging to Kennedy class I, where the canine was a border of shortened dental arch. For this procedure paralelometar Unit "Degussa" with a special measuring device was used. The undercut depth could be read directly within a range of 0-1.0 mm. Results show that unprepared lower canines have poor possibilities for retention removable partial denture with clasps. Our positive clinical experiences in recontouring vestibular surfaces of the abutment teeth point to two methods of making an artificial undercut: non-invasive (making an artificial undercut using composite materials) and invasive (using modified fixed restorations). Considering fact that vestibular surfaces of lower canines as abutment teeth are in most cases without undercuts, recontouring of this surface in almost all occasions is necessary. If vestibular undercuts don't exist, non-invasive techniques should always have advantages to invasive techniques. The vestibular surfaces of abutment teeth might be recontoured by using non-invasive techniques with minimal destruction of integrity of teeth. Lately, the composite materials are used for forming artificial undercut.