The Influence of Contemporary Denture Base Fabrication Methods on Residual Monomer Content, Flexural Strength and Microhardness.

(1) Background: Digital technologies are available for denture base fabrication, but there is a lack of scientific data on the mechanical and chemical properties of the materials produced in this way. Therefore, the aim of this study was to investigate the residual monomer content, flexural strength and microhardness of denture base materials as well as correlations between investigated parameters. (2) Methods: Seven denture base materials were used: one conventional heat cured polymethyl methacrylate, one polyamide, three subtractive manufactured materials and two additive manufactured materials. High-performance liquid chromatography was used to determine residual monomer content and the test was carried out in accordance with the specification ISO No. 20795-1:2013. Flexural strength was also determined according to the specification ISO No. 20795-1:2013. The Vickers method was used to investigate microhardness. A one-way ANOVA with a Bonferroni post-hoc test was used for the statistical analysis. The Pearson correlation test was used for the correlation analysis. (3) Results: There was a statistically significant difference between the values of residual monomer content of the different denture base materials (p < 0.05). Anaxdent pink blank showed the highest value of 3.2% mass fraction, while Polident pink CAD-CAM showed the lowest value of 0.05% mass fraction. The difference between the flexural strength values of the different denture base materials was statistically significant (p < 0.05), with values ranging from 62.57 megapascals (MPa) to 103.33 MPa. The difference between the microhardness values for the different denture base materials was statistically significant (p < 0.05), and the values obtained ranged from 10.61 to 22.86 Vickers hardness number (VHN). A correlation was found between some results for the material properties investigated (p < 0.05). (4) Conclusions: The selection of contemporary digital denture base manufacturing techniques may affect residual monomer content, flexural strength and microhardness but is not the only criterion for achieving favourable properties.

Tensile Bond Strength between Different Denture Base Materials and Soft Denture Liners.

(1) Background: Various materials are available for CAD-CAM denture base fabrication, for both additive and subtractive manufacturing. However, little has been reported on bond strength to soft denture liners. Therefore, the aim of this study was to investigate tensile bond strength, comparing between different denture base materials and soft denture liners. (2) Methods: Seven different materials were used for denture base fabrication: one heat-polymerized polymethyl methacrylate, three materials for subtractive manufacturing, two materials for additive manufacturing and one polyamide. Two materials were used for soft denture lining: one silicone-based and one acrylate-based. The study was conducted according to the specification ISO No. 10139-2:2016, and the type of failure was determined. The Kruskal-Wallis test with Dunn's post hoc test was used to analyse the values of tensile bond strength, and Fisher's exact test was used to analyse the type of failure. p Values < 0.05 were considered statistically significant. (3) Results: The tensile bond strength values were not statistically significantly different combining all the materials used for denture base fabrication with the acrylate-based soft denture liner (p > 0.05), and the average values ranged between 0.19 and 0.25 Mpa. The tensile bond strength values of the different denture base materials and silicone-based denture liner were statistically significantly different (p < 0.05), and the average values ranged between 1.49 and 3.07 Mpa. The type of failure was predominantly adhesive between polyamide and both additive-manufactured denture base materials in combination with the acrylate-based soft liner (p < 0.05). (4) Conclusions: The use of digital technologies in denture base fabrication can have an influence on different tensile bond strength values for soft denture liners, with different types of failure when compared with heat-cured PMMA. Similar tensile bond strength values were found between the acrylate-based soft denture liner and denture base materials. Significant differences in tensile bond strength values were found between the silicone-based soft denture liner and denture base materials, where the additive-manufactured and polyamide denture base materials showed lower values than heat-cured PMMA and subtractive-manufactured denture base materials.

Influence of Different Surface Pretreatments of Zirconium Dioxide Reinforced Lithium Disilicate Ceramics on the Shear Bond Strength of Self-Adhesive Resin Cement.

AIM: To analyze the influence of different surface pretreatments of zirconium dioxide reinforced lithium disilicate ceramics on the shear bond strength of self-adhesive resin cement. MATERIALS AND METHODS: Eighty-four zirconium reinforced lithium disilicate disc Vita suprinity (Vita Zahnfabrick, Bad Säckingen, Germany) 14x12x2 mm specimens were fabricated according to the manufacturer's recommendations. The specimens were embedded in acrylic resin blocks and randomly divided in seven groups (n=12/each) accorrding to the treatment: Group 1- 10% hydrofluoric acid; Group 2- silane; Group 3- hydrofluoric and silane; Group 4- sandblasting with silane; Group 5- Er: YAG laser+ silane; Group 6- Nd: YAG laser + silane; and the control group, in which the specimens were not treated. Round shape composite discs (Filtek Bulk fill, 3M ESPE, St.Paul, Minnesota, USA) with 3.5 mm diameter, were made for shear bond strength testing, and then cemented to the ceramic sample surface using composite cement (RelyX U200 Automix, 3M ESPE, Neuss, Germany). After cementing the composite disc on the sample, the samples were subjected to shear bond strength test of 10 N with a "stress rate" of 1 MPa / s. To determine the nature of the fracture (adhesive, cohesive or adhesive-cohesive), the broken samples were examined under a stereomicroscope. The ANOVA test and the Tukey test were used to compare the values ​​of the bond strength characteristics between different types of materials. All tests were performed with a significance level of α = 0.05. RESULTS: There was a significant difference in the shear bond strength of self-adhesive cement to dental lithium-disilicate ceramics reinforced with zirconium dioxide after different preparation protocols (p<0, 05). The treatment of lithium disilicate ceramics reinforced with zirconium dioxide by silanization, sandblasting + silanization, Nd: YAG + silanization resulted in significantly higher bond strength compared to the control group. There was statistically higher bond strength of self-adhesive cement after pretreatment of lithium disilicate ceramics Nd: YAG + silanization compared to Er: YAG + silanization (p <0.05). Adhesive fracture dominated in the control group, sandblasting + silanization group, and in the laser groups, while mixed fracture dominated in other groups. CONCLUSION: Under the limitations of this study, the Nd:YAG irradiation with silanization could be used as pretreatment for providing greater shear bond strength of self-adhesive resin cement to zirconium reinforced lithium disilicate.

Articular Eminence Morphology of American Historic and Contemporary Populations.

OBJECTIVES: This study was performed to determine the values of the articular eminence inclination (AEI), the articular eminence height (AEH), and the length of the articular eminence curved line (AEL) among American prehistoric and contemporary populations. MATERIALS AND METHODS: The study was carried out on 120 human dry skulls divided into 4 groups: Illinois group (IP), Kentucky group (KP), African Americans group (AAP) and American Caucasians group (ACP). Each group comprised 30 human dry skulls. Measurements of AEI (by two methods), AEH and AEL were performed using computer software on 5 sagittal sections through silicone molds of the articular eminence. The obtained results were statistically analyzed at significance level of p < 0.05. RESULTS: No statistically significant differences of AEI, AEH and AEL values were obtained among American populations (IP, KP, AAP, ACP) neither by body side, sex and age (p > 0.05). The mean AEI M1 values ranged from 31.56° to 38.72°, the mean AEI M2 values ranged from 44.14° to 58.37°, the mean AEH ranged from 5.82 to 6.86 mm, and the mean AEL values ranged from 11.57 to 12.73 mm. CONCLUSIONS: AEI, AEH, AEL values are variables, but they did not differ significantly among American populations. Left-right differences as the result of natural body asymmetry were not statistically significant. Sex and age did not significantly affect the articular eminence morphology.

A cohort study on short mini-implants for mandibular overdentures compared to those of standard length.

OBJECTIVES: To assess peri-implant bone level, survival and success rates of short (6 or 8 mm long) one-piece mini-implants (MDIs) in edentulous patients with extremely resorbed alveolar ridge (interforaminal height <10 mm) rehabilitated with mandibular implant overdentures and to compare them with patients having standard length MDIs in 1-year prospective clinical study. MATERIAL AND METHODS: The Short MDI group consisted of 28 participants with interforaminal height ≤10 mm. Implants being, both, short and slim (short MDIs: 6 or 8 mm long, 2 or 2.5 mm wide) were inserted. The Standard-MDI group included 35 participants (interforaminal height >13 mm) who received standard length MDIs (10-14 mm long, 2 or 2.5 mm wide). Primary outcomes were assessments of MDI peri-implant bone level, survival and success rates; secondary outcomes were assessments of peri-implant tissue, oral hygiene, and prosthodontic maintenance. RESULTS: The Short MDI group had mean marginal bone loss (MBL) of 0.26 ± 0.35 mm, 6.4% of failure, and 92.6% of, both, success and survival rates. The Standard-MDI group had mean MBL of 0.34 ± 0.40 mm, 5% of failure, 95% of survival, and 94.3% success. There were no significant differences in MBL (p = .420), survival (p = .414), and success (p = .571) between the groups. The Short MDI group had significantly less plaque (p = .001) and bleeding on probing (p < .001). CONCLUSION: Within the limitations of this study, short MDIs (6 or 8 mm long) in extremely atrophied mandibles (interforaminal height <10 mm) showed good clinical results in the first year of function.

Short-term Postoperative Pain and Swelling Associated with Mini and Standard-Size Implants in the Same Patients.

PURPOSE: To assess short-term postoperative pain and swelling after insertion of mini dental implants (MDI) and standard-size implants (SSI) in the same patients at different times. MATERIALS AND METHODS: A convenience sample of 42 patients (22 females, 20 males; 58 to 73 years old) participated. Half of the participants received MDIs first, and the other half received SSIs first. Self-perceived pain and swelling at 1, 3, 5, 7, and 10 days postoperative were assessed using a 0-10 visual analog scale. RESULTS AND CONCLUSION: Flapless MDI insertion led to significantly less intense postoperative pain, less intake of analgesics, and almost no swelling compared to SSI insertion.

Attitudes of the Students from the School of Dental Medicine in Zagreb towards CAD/CAM.

AIM: Due to fast and continuing advances in digital dental technology it is important to provide appropriate CAD/CAM education of preclinical (PS) and clinical (CS) dental students. Therefore, the aim of this study was to determine the knowledge and attitudes on CAD/CAM technology of PS and CS at the School of Dental Medicine, University of Zagreb since the obtained results can show the level of students' knowledge and possibly a need for additional education. MATERIALS AND METHODS: This study included 216 undergraduate dental students from the School of Dental Medicine in Zagreb: 77 (35.6%) of preclinical students (PS) and 139 (64.4%) of clinical students (CS). All participants filled out the questionnaire specially designed for this study. The obtained data were statistically analyzed with a significance level of p<0.05. RESULTS: Most of the students (182, 84.23%) heard about CAD/CAM technology at regular lectures held at the School (p<0.05). Regardless of their level of education, most of the students (204, 94.4%) did not attend any CAD/CAM course which were not held within regular lectures at the School (p<0.05). Most of PS (72, 33.3%) and most of CS (133, 61.6%) participants believe that they are not sufficiently informed about CAD/CAM technology (p<0.05). CONCLUSION: Although most of the students (PS and CS) heard about CAD/CAM technology, it could be concluded that they are not sufficiently informed and that additional education on CAD/CAM technology is required. Also, CS students do not posses greater knowledge about CAD/CAM technology than PS students.

Rehabilitation of an Extremely Resorbed Edentulous Mandible by Short and Narrow Dental Implants.

Serious consequences of long-term complete denture wearing may be extreme residual ridge atrophy and a reduced area of keratinized oral mucosa of a denture-bearing area. This paper presents five clinical cases of extreme mandibular ridge atrophy, rehabilitated by means of mandibular overdentures retained by short mini dental implants. The patients had a reduced mandibular bone volume in the interforaminal region, bone height less than 10 mm, and buccolingual bone width less than 4 mm. In order to avoid bone augmentation, patients received four short mini dental implants (MDIs) (6 or 8 mm long; 2.0 or 2.5 mm wide) for the support of mandibular overdentures, which is a new rehabilitation option. After insertion, the MDIs were early loaded with new mandibular overdentures reinforced with the CoCr framework. The patients have been wearing their overdentures for 2 years. One MDI broke during insertion and a new one was added. One patient lost one MDI but successfully continued to wear the overdenture retained by the remaining three MDIs. Mean marginal bone loss (MBL) was 0.20 ± 0.19 mm. Patients significantly improved their OHRQoL and chewing function by reducing the summary scores of the OHIP-14 and the chewing function questionnaires. The improvements remained unchanged throughout the observation period.

Treatment Outcomes Based on Patients' Self-Reported Measures after Receiving New Clasp or Precision Attachment-Retained Removable Partial Dentures.

PURPOSE: To evaluate effects of a treatment taking into consideration esthetics, chewing, and oral health-related quality of life (OHRQoL) of two tooth replacement strategies for maxillary partially edentulous patients with clasp (C-RPD) and precision attachment (PA-RPD) retained removable partial dentures (RPD). MATERIALS AND METHODS: The study included 150 patients (72 men, 78 women) who received maxillary RPDs; 88 patients received clasp and 62 patients received precision attachment retained RPDs. Patients completed three questionnaires before treatment and again 3 months after treatment: the Orofacial Esthetic Scale (OES), the Oral Health Impact Profile (OHIP-14), and the Chewing Function Questionnaire (CFQ). Statistical analysis comprised descriptive statistics, paired t-test, and two-factor ANOVA. RESULTS: Both RPD treatments yielded better after-treatment summary scores when compared with the baseline scores (p < 0.01); however, better results were obtained in the PA-RPD group. Gender, as a single factor, did not yield significant effects; mutual interaction of retention type and gender yielded significant effects. The PA-RPD female group assessed esthetics, chewing function, and OHRQoL significantly better than males, and significantly worse than males in the C-RPD group. The covariate baseline scores yielded statistically significant effects; patients with worse pretreatment condition benefited more from both therapies. CONCLUSIONS: Treatment outcomes were better in the PA-RPD group than the C-RPDs. Women showed greater concern for the treatment outcomes; their rates were significantly better than in male patients in the PA-RPD group; however, when their satisfaction was lower, their rates were significantly worse than in male patients (in the C-RPD group).

Simplified Prosthetic Rehabilitation of a Patient after Oral Cancer Removal.

The treatment of patients with oral cancer is complex: a multidisciplinary approach needs to be taken and maxillofacial and oral surgeons, an oncologist, a prosthodontist should be included, and a psychologist is often needed. This case report describes the prosthetic rehabilitation of a patient after surgical removal of oral cancer with obturator prosthesis. Resection cavity was located in central part of the hard palate and the condition belonged to Aramany class 3 maxillary defects. The two-step impression technique of denture bearing area was used and the resection of cavity was performed. A primary impression-the impression of denture bearing area was made using irreversible hydrocolloid material, while the second impression - the impression of resection cavity was made using condensation silicone material and obturator prosthesis framework. The obturator prosthesis replaced lost teeth, improved oral function and esthetics at minimal costs.

Oral Health-Related Quality of Life in Different Types of Mandibular Implant Overdentures in Function Longer Than 3 Years.

PURPOSE: The aim of this study was to evaluate the oral health-related quality of life (OHRQoL) of patients treated with three different types of mandibular implant overdentures (IOD) after at least 3 years in function. MATERIALS AND METHODS: A total of 122 patients treated with mini implant (50), locator (56), or bar (16) mandibular IODs participated. Modified plaque (PI) and gingival (GI) indices were also assessed. RESULTS: Older patients and patients with mini mandibular IODs were the most satisfied with their OHRQoL. The bar overdenture presented the worst PI and GI results. CONCLUSION: The mini mandibular overdenture patients were assessed with a better OHRQoL than those with bar and locator IODs.

Differences in skeletal components of temporomandibular joint of an early medieval and contemporary Croatian population obtained by different methods.

The temporomandibular joint (TMJ) is one of the most complex joints in the human body. The anatomical configuration of the TMJ allows for a large range of mandibular movements as well as transmission of masticatory forces and loads to the skull base. The measurements of the TMJ's anatomical structures and their interpretations contribute to the understanding of how pathological changes, tooth loss, and the type of diet (changing throughout human history) can affect biomechanical conditions of the masticatory system and the TMJ. The human TMJ and its constituent parts are still the subject of extensive investigation and comparisons of measurement methods are being made in order to determine the most precise and suitable measurement methods. The aim of this study has been to examine the morphology of skeletal components of TMJ of an early medieval population (EMP) in Croatia and to compare measured values with TMJ values of the contemporary Croatian population (CP) using various methods of measurement. The study was performed on 30 EMP specimens - human dry skulls, aged from 18 to 55 years, and 30 CP human dry skulls, aged from 18 to 65 years. Only fully preserved specimens (in measured areas) were included. The articular eminence (AE) inclination was measured in relation to the Frankfurt horizontal using two methods. Also, the AE height (glenoid fossa depth) and the length of the curved line - highest to the lowest point of the AE were measured. Measurements were performed on lateral skull photographs, panoramic radiographs and lateral cephalograms using VistaMetrix software on skull images. The results were statistically analyzed using SPSS statistical software. No statistically significant differences were obtained for AE parameters between the EMP and CP populations independent of age and gender. However, statistically significant (p<0.05) differences were revealed when comparing results of three different measuring methods. It could not be determined which of the used measurement methods is the most accurate due to the different results obtained as well as the presence of possible shortcomings and limitations of the various methods (measuring points are difficult to determine and/or they are not clearly observed in the investigated images to be precisely marked and measured; distortion and magnification of structures on radiographic images are present). Therefore, due to the limitations of this study, the obtained results could serve only as orienting information.

Articular Eminence Inclination in Medieval and Contemporary Croatian Population

Articular eminence inclination (AEI) of the temporomandibular joint leads the mandible in its movements. Therefore, the aim of the present study was to determine AEI values in medieval (MP) and recent (RP) Croatian population. The study was carried out on two groups of specimens: first group with 30 MP human dry skulls, while the other, serving as control group consisted of 137 dry skulls. The AEI was measured on lateral digital skull images as the angle between the best fi t line drawn along the posterior wall of the articular eminence and the Frankfurt horizontal plane. No statistically significant (p>0.05) differences between the left and right side AEI were found between MP skulls and RP skulls. The mean value of MP AEI was 45.5˚, with a range of 20.9˚-64˚. The mean RP AEI value was steeper (61.99˚), with a range of 30˚-94˚. Difference between the mean MP and RP AEI values was statistically significant (p<0.05). Values of AEI vary a lot. Nonsignificant differences between the left and right side AEI confirmed the natural left-right side asymmetry. The values of AEI differ between the RP and MP groups, most probably due to different type of food consumption in medieval time, and consequently different masticatory loads and forces.

Flexible Removable Partial Denture Prosthesis: A Survey of Dentists' Attitudes and Knowledge in Greece and Croatia.

PURPOSE: The aim of this study was to investigate through a questionnaire the knowledge, attitudes and possible differences in the use of flexible RPDPs among dentists in Greece and Croatia. MATERIAL AND METHODS: A questionnaire of 16 questions was originally created in English, translated into Greek and Croatian language following a two way translation and tested for apprehension, precision, clarity and homogeneity by a number of native English speaking Greek and Croatian dentists. Following the necessary corrections, the questionnaires replicated in two online surveys and their addresses with an informed consent were sent by emails to nearly 4000 dentists in each country to participate. Collected data were analyzed by chi-square tests at a= .05 level of significance. RESULTS: 378 dentists from Greece and 304 from Croatia participated in the study. 137(36.2%) dentists from Greece and 56(18.4%) from Croatia provided flexible RPDPs to their patients. Statistical analysis for all providers indicated no significant difference between genders (P>.05), significant differences between age groups (P<.01), years of practice (P<.05), specialization (P <.001), and instruction on flexible prostheses (P <.001). The analysis between the two countries showed differences for gender and age groups (P<.01) but no differences between experienced, specialized or instructed groups (P >.05). CONCLUSION: The survey indicated differences between the two countries in the percentages of dentists using, selecting and providing RPDPs for their patients. Practitioners' age, years in practice and instruction were associated with the provision of the prostheses, while comfort, esthetics and cost were the reasons for deciding to use the flexible RPDPs. CONCLUSION: Although dentists are not educated in their schools about flexible RPDPs, almost a third of them offer this treatment to their patients. Long term success of these devices depends on clinical education, more experience and definitely more research.

Knowledge and awareness of dental implants among elderly people in Croatia.

PURPOSE: The use of inserted dental implants is growing every day in order to improve retention and stability of complete removable dental prostheses (RDPs), especially in the mandible. Therefore, the aim of this study was to examine the knowledge and awareness of dental implants among elderly people wearing complete RDPs. MATERIALS AND METHODS: This study, based on answers from a questionnaire designed for the purpose of this study, included 301 participants wearing complete RDPs from elderly care homes with average age of 74 years. RESULTS: The awareness of dental implants was statistically significantly (p < 0.05) affected by the participants' age, residence size, and their level of education. Younger participants (x¯ = 70 years) had heard about dental implants (56.5%; p < 0.05) and believed in the possibility of retaining complete RPDs using dental implants (56.1%; p < 0.05). Among participants living in places with populations of 10,000 or fewer residents, more had not heard about dental implants (59.4%; p < 0.05). Among participants who had completed college/university or high school, there were a higher number of participants who had heard about dental implants (82.4%; p < 0.05). CONCLUSION: Although more than half of the participants had heard of dental implants, this did not mean they were well informed about the implant insertion procedure and the costs for such a treatment. In conclusion, awareness of dental implants in studied participants was insufficient. The results reinforce the need for better education and the provision of proper information to elderly people about dental implants and implant treatment options.

Factors Affecting Oral Health-Related Quality of Life Among Elderly Croatian Patients.

OBJECTIVE OF WORK: Oral health-related quality of life (OHRQoL) as a multidimensional concept is affected by many factors. Therefore, the aim of this study was to determine which demographic and subjective factors are significantly affecting the OHRQoL among the elderly people wearing complete removable dental prostheses (CRDP). MATERIALS AND METHODS: This questionnaire-based study included 301 participants, residents of elderly care homes (in Zagreb and Slavonski Brod, Croatia) wearing maxillary and/or mandibular CRDP. The questionnaire used in this study consisted of two sections; the first section included questions giving general information and in the second section the Croatian version of Oral Health Impact Profile (OHIP)-49 questionnaire with 49 items representing seven OHIP domains was used. RESULTS: Participants were aged between 60-99 years, with average age of 74 ± 12.1 years. OHIP summary score was 26.5. The highest average OHIP mean values in the domain of functional limitation amounted to 6.7, physical pain 5.1, and physical disability 5.9. The participants' age, education, profession, residence place size, type of CRDP, and the time of denture wearing period all statistically significantly affected OHRQoL (p < 0.05). CONCLUSIONS: General and sociodemographic factors had a significant influence on the participant's subjective perception of oral health and OHRQoL. Younger participants, participants from rural places, those with lower levels of education, and shorter period of denture wearing demonstrated a higher impact on OHRQoL.

A two-step (altered cast) impression technique in the prosthetic rehabilitation of a patient after a maxillectomy: a clinical report.

This clinical report describes the prosthetic rehabilitation complicated by trismus (as a consequence of surgery and radiation therapy) of a patient with an acquired maxillary defect, after surgical removal of the right maxillary sinus tumor. The patient was restored with a partial removable dental prosthesis with a hollow bulb obturator to obtain orofacial rehabilitation and defect obturation. Precise obturation requires an accurate impression of the resection defect. A 2-step impression was performed because of trismus. A primary maxillary impression was made with an irreversible hydrocolloid, while a secondary (altered cast) impression was made with a silicone material by using the obturator cast framework as a tray. In that way an altered cast was produced. Subsequently, an obturator prosthesis was processed with a conventional technique.

Prosthetic modalities used to treat cleft palate patients in a university clinic: a 10-year review.

Cleft palate patients are not usually seen in general dental clinics, but this congenital anomaly is one of the most frequent of cases. General dental practitioners are usually unwilling or/and not sufficiently trained to treat such patients for whom rehabilitation and interdisciplinary cooperation is often needed. The aim of this study was to determine the incidence of prosthetic modalities most frequently used by licensed prosthodontists for prosthetic rehabilitation of cleft palate patients. Participants in this study were 56 cleft palate patients (aged 23-66 years) who received prosthetic treatment between 2000 and 2010. Patients' dental status and prosthetic modalities used were noted from patient records archived at Department of Prosthodontics, School of Dental Medicine, University of Zagreb. Data analyses revealed that combined prosthetic constructions (fixed + removable, p < 0.05) were the most frequently used. In a group of molar teeth, the most frequent fixed prosthetic modalities were crowns with rests; in a group of premolar teeth, telescopic crowns; on canines, metal ceramic crowns and telescopic crowns; and in a group of incisors, metal ceramic pontics (p < 0.05). Understanding the distribution of prosthetic modalities for cleft palate patients could serve to guide dental practitioners towards planning adequate prosthetic treatment for their patients since only a well-planned prosthetic therapy will result in satisfactory function and alleviation of the deformities.

Human papillomavirus in the lesions of the oral mucosa according to topography.

BACKGROUND: The association between human papillomavirus (HPV) types and oral lesions has been shown in many studies. Considering the significance that HPV has in the development of malignant and potentially malignant disorders of the oral mucosa, the purpose of this study was to investigate the prevalence of HPV DNA in different oral lesions. In addition, we wanted to elucidate whether the HPV infection is associated predominantly with either the lesion or a particular anatomic site of the oral cavity. METHODOLOGY/PRINCIPAL FINDINGS: The study included 246 subjects with different oral lesions, and 73 subjects with apparently healthy oral mucosa (controls). The oral lesions were classified according to their surface morphology and clinical diagnosis. The epithelial cells were collected with a cytobrush from different topographic sites in the oral cavity of the oral lesions and controls. The presence of HPV DNA was evaluated by consensus and type-specific primer-directed polymerase chain reaction. The HPV positivity was detected in 17.7% of oral lesions, significantly more than in apparently healthy mucosa (6.8%), with a higher presence in benign proliferative mucosal lesions (18.6%). High-risk HPV types were predominantly found in potentially malignant oral disorders (HPV16 in 4.3% and HPV31 in 3.4%), while benign proliferative lesions as well as healthy oral mucosa contained mainly undetermined HPV type (13.6 and 6.8%, respectively). CONCLUSIONS/SIGNIFICANCE: The distribution of positive HPV findings on the oral mucosa seems to be more associated with a particular anatomical site than the diagnosis itself. Samples taken from the vermilion border, labial commissures, and hard palate were most often HPV positive. Thus, topography plays a role in HPV prevalence findings in oral lesions. Because of the higher prevalence of the high-risk HPV types in potentially malignant oral disorders, these lesions need to be continuously controlled and treated.

Denture relining as an indicator of residual ridge resorption.

AIM: Residual ridges change in shape and reduce in size due to alveolar bone resorption. Therefore, the purpose was to investigate changes in denture base thickness (DBT) and interocclusal rest space (IRS) with regard to the denture relining procedure. METHODS: The IRS and DBT were measured (before and after denture relining) in the case of 74 patients and their removable dental prostheses by using a precise sliding gauge. The DBT measuring was performed in 6 points for maxillary and in 3 points for mandibular removable dental prosthesis. The IRS values were measured as the distance (in mm) between the incisal edges of the maxillary and mandibular central incisors with patient's mandible in a physiological "rest position" with head and neck in the upright posture. RESULTS: In a group of patients wearing maxillary and mandibular removable dental prosthesis mean values of DBT after denture relining were statistically significantly higher (p <0.05) in almost all measuring points. The IRS mean values after relining were statistically significantly lower (p <0.05). Statistically significant differences (p <0.05) of DBT were also observed in groups of "day-night time" and "day time" denture wearers, and in a group of patients for whom a period shorter than one year had passed since the last tooth extraction and the time when a functional impression for removable dental prostheses was taken. CONCLUSION: The DBT and IRS values change after the denture relining procedure due to the alveolar bone resorption. Therefore, these measures could be used as resorption indicators in dental practice.