Raquel Castillo-Oyagüe

Influence of sandblasting granulometry and resin cement composition on microtensile bond strength to zirconia ceramic for dental prosthetic frameworks.

OBJECTIVES To evaluate the effect of the particle size of sandblasting and the composition of the resin cement on the microtensile bond strength (MTBS) to zirconia. METHODS Forty zirconia blocks (Cercon, Dentsply) were polished and randomly treated as follows: Group 1 (NT): no treatment; Group 2 (APA-I): airborne particle abrasion (Cobra, Renfert) using 25-μm aluminium-oxide (Al(2)O(3))-particles; Group 3 (APA-II): APA with 50-μm Al(2)O(3)-particles; and Group 4 (APA-III): APA using 110-μm Al(2)O(3)-particles. Ceramic blocks were duplicated in composite resin. Samples of each pretreatment group were randomly divided into two subgroups depending on the resin cement used for bonding the composite disks to the treated zirconia surfaces. Subgroup 1 (PAN), which was a 10-MDP-containing luting system, used Clearfil Ceramic Primer plus Panavia F 2.0 (Kuraray) and Subgroup 2 (BIF) used Bifix SE (VOCO) self-adhesive cement. After 24h, bonded specimens were cut into 1±0.1mm(2) sticks. MTBS values were obtained using a universal testing machine (cross-head speed=0.5mm/min). Failure modes were recorded and the interfacial morphology of the debonded microbars was SEM-assessed. Two-way ANOVA, Student-Newman-Keuls tests, and the step-wise linear regression analysis were performed with the MTBS being the dependent variable (p<0.05). RESULTS Despite the sandblasting granulometry, PAN bonded to air-abraded surfaces attained the highest MTBS and frequently showed mixed fractures. BIF recorded no significant differences in MTBS depending on the conditioning method, and registered the highest rates of premature and adhesive failures. CONCLUSIONS The 10-MDP-containing luting system seems to be the most suitable to bond zirconium-oxide ceramic, mainly after sandblasting.

Oral health-related quality of life in complete denture wearers depending on their socio-demographic background, prosthetic-related factors and clinical condition

Objectives: To investigate the differences in impact on oral health-related quality of life (OHRQoL) among complete denture wearers depending on their socio-demographic characteristics, prosthetic-related factors and oral status. Study Design: 51 patients aged 50-90 years treated, from 2005 to 2010, with at least one complete denture at the Department of Buccofacial Prostheses of the Complutense University (Madrid) were enrolled in this cross-sectional study. All of the participants answered the Oral Health Impact Profile (OHIP-14sp) questionnaire. The additive scoring method was used. The prevalence of impacts was calculated by using the occasional threshold (OHIP-14sp score≥2). Socio-demographic and prosthetic-related variables were gathered. Patients underwent clinical examination to assess their oral condition. Descriptive probes and Chi-Square tests were run (p≤0.05). Results: The predominant participants’ profile was that of a man with a mean age of 69 years wearing complete dentures in both the maxilla and the mandible. The prevalence of impact was 23.5%, showing an average score of 19±9.8. The most affected domains were “functional limitation” and “physical pain”, followed by “physical disability”. Minor impacts were recorded for the psychological and social subscales (“psychological discomfort”, “psychological disability”, “social disability” and “handicap”). The prosthesis’ location significantly influenced the overall patient satisfaction, the lower dentures being the less comfortable. Having a complete removable denture as antagonist significantly hampered the patient satisfaction. Patients without prosthetic stomatitis and those who need repairing or changing their prostheses, recorded significantly higher OHIP-14sp total scores. Conclusions: The use of conventional complete dentures brings negative impacts in the OHRQoL of elderly patients, mainly in case of lower prostheses that required reparation or substitution, with a removable total denture as antagonist. The prosthetic stomatitis in this study was always associated to other severe illness, which may have influenced the self-perceived discomfort with the prostheses, as those patients were daily medicated with painkillers. Key words:Oral Health Impact Profile (OHIP), oral health-related quality of life (OHRQoL), patient satisfaction, complete denture, elderly patients.

Misfit and microleakage of implant-supported crown copings obtained by laser sintering and casting techniques, luted with glass-ionomer, resin cements and acrylic/urethane-based agents.

OBJECTIVES This study evaluated the marginal misfit and microleakage of cement-retained implant-supported crown copings. METHODS Single crown structures were constructed with: (1) laser-sintered Co-Cr (LS); (2) vacuum-cast Co-Cr (CC) and (3) vacuum-cast Ni-Cr-Ti (CN). Samples of each alloy group were randomly luted in standard fashion onto machined titanium abutments using: (1) GC Fuji PLUS (FP); (2) Clearfil Esthetic Cement (CEC); (3) RelyX Unicem 2 Automix (RXU) and (4) DentoTemp (DT) (n=15 each). After 60 days of water ageing, vertical discrepancy was SEM-measured and cement microleakage was scored using a digital microscope. Misfit data were subjected to two-way ANOVA and Student-Newman-Keuls multiple comparisons tests. Kruskal-Wallis and Dunns tests were run for microleakage analysis (α=0.05). RESULTS Regardless of the cement type, LS samples exhibited the best fit, whilst CC and CN performed equally well. Despite the framework alloy and manufacturing technique, FP and DT provide comparably better fit and greater microleakage scores than did CEC and RXU, which showed no differences. CONCLUSIONS DMLS of Co-Cr may be a reliable alternative to the casting of base metal alloys to obtain well-fitted implant-supported crowns, although all the groups tested were within the clinically acceptable range of vertical discrepancy. No strong correlations were found between misfit and microleakage. Notwithstanding the framework alloy, definitive resin-modified glass-ionomer (FP) and temporary acrylic/urethane-based (DT) cements demonstrated comparably better marginal fit and greater microleakage scores than did 10-methacryloxydecyl-dihydrogen phosphate-based (CEC) and self-adhesive (RXU) dual-cure resin agents.

Outcome of single immediate implants placed in post-extraction infected and non-infected sites, restored with cemented crowns: a 3-year prospective study.

OBJECTIVES To compare the survival of immediate implants placed in postextraction infected and non-infected sites, restored with cemented crowns. METHODS Thirty-six implants were immediately placed in non-infected sockets (control group (CG), n=18), and in infected alveoli (test group (TG), n=18) that had been debrided, curetted, cleaned with 90% hydrogen peroxide, irradiated with yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser, and irrigated with a sterile solution. Guided bone regeneration was performed under antibiotic coverture. All study patients had both a CG and a TG site. The implant osteotomy sites were extended 3-4 mm beyond the apical extent of the sockets to achieve primary stability for the implants. The prosthetic phase occurred 4.5 months after surgery. Success criteria were accepted as the presence of implant stability, absence of a radiolucent zone around the implants, absence of mucosal suppuration, and lack of pain. Clinical evaluations were performed at baseline, and at 12, 24, and 36 months of follow-up. RESULTS All of the implants were osseointegrated 3 months after surgery. The 3-year survival rate was 94.44% for TG, and 100% for CG. The clinical and radiographic variables tested yielded no significant differences among groups at 36 months. CONCLUSIONS Under the tested conditions, immediate implant placement can be considered a predictable treatment option for the restoration of fresh postextraction infected sockets. CLINICAL SIGNIFICANCE Immediate implants may be indicated for replacing teeth lost due to chronic periapical lesions with endodontic failure history when appropriate preoperative procedures are taken to clean and decontaminate the surgical sites.

Impact of various screwed implant prostheses on oral health-related quality of life as measured with the QoLIP–10 and OHIP–14 scales: A cross-sectional study

OBJECTIVES This study aimed to validate the Quality of Life with Implant-Prostheses (QoLIP-10) questionnaire for assessing the impact of screwed implant-supported rehabilitations on oral health-related quality of life (OHRQoL). METHODS 131 patients wearing screw-retained implant restorations were assigned to the following groups: Group 1 (HP; n=50): fixed-detachable hybrid prostheses (control), Group 2 (S-PD; n=43): metal-ceramic screwed partial dentures, and Group 3 (S-CD; n=38): metal-ceramic screwed complete dentures. Impacts on OHRQoL were evaluated using the QoLIP-10 and Oral Health Impact Profile (OHIP-14sp) scales. Data on global oral satisfaction, socio-demographics, health-behaviours, and prosthetics were gathered. Reliability and validity of the QoLIP-10 were investigated for screwed prosthesis wearers. The Spearmans rank test was applied to determine the correlation between both indices. Descriptive and non-parametric probes were run to evaluate the influence of the study variables on OHRQoL. RESULTS The QoLIP-10 confirmed its psychometric capacity for screwed prosthesis wearers. Both tests were inversely correlated. HP wearers reported the worst dental-facial aesthetics, performance, and functional limitation outcomes. Gender, education level, complaints about the mouth, perception of treatment needs, and prosthetic status modulated the OHRQoL. CONCLUSIONS Screwed implants restorations provide better OHRQoL than do fixed-detachable hybrid prostheses.

Clinical evaluation of the incidence of prosthetic complications in implant crowns constructed with UCLA castable abutments. A cohort follow-up study

OBJECTIVES To evaluate the incidence of prosthetic complications in implant-retained crowns made with UCLA castable abutments and to identify possible risk factors with a view to establishing recommendations to help predict the success of such restorations. METHODS A cohort follow-up study was carried out in 71 partially dentate patients rehabilitated with 93 implant-retained single crowns. Data regarding socio-demographic background, anatomical features, implant-, and prosthesis-related variables were recorded. The incidence rate (%), relative risk (RR) and odds ratio (OR) were applied for predictive risk factors. ANOVA and Student t-tests were used to compare quantitative variables, the chi-square test was used to compare proportions and also a logistic regression analysis was performed. The statistical significance was set at α = 0.05. RESULTS Two implants (2.2%) were lost during the first year of function. The incidence of prosthetic complications in the observed mean period (26.2 ± 15.4 months) was 11.9%, consisting of screw loosening (10.8%) and ceramic fracture (1.1%). A higher tendency for prosthetic complications was noticed in posterior mandibular crowns restoring saddles longer than 10 mm with mesiodistal cantilevers longer than 6mm, having natural antagonists, after long-term use (>20 months), with initial torque values superior than 30 Ncm. CONCLUSIONS Screw loosening is the most frequent complication in implant-retained crowns fabricated with UCLA abutments cast in cobalt-chromium. Nevertheless, the connection usually remains stable after retightening the screws. A high survival rate was recorded, and these prostheses may be a suitable treatment option. CLINICAL SIGNIFICANCE Based on the study findings, the risk of prosthetic complications is expected to increase when long-span posterior edentulous areas are rehabilitated with single implant-supported crowns. The antagonist occlusal plane should be restored to prevent torsional forces and overloading. Implant systems with initial torque values less than 30 Ncm should be selected.

Effect of electric arc, gas oxygen torch and induction melting techniques on the marginal accuracy of cast base-metal and noble metal-ceramic crowns

OBJECTIVES The aim of this study was to identify the most appropriate alloy composition and melting technique by evaluating the marginal accuracy of cast metal-ceramic crowns. METHODS Seventy standardised stainless-steel abutments were prepared to receive metal-ceramic crowns and were randomly divided into four alloy groups: Group 1: palladium-gold (Pd-Au), Group 2: nickel-chromium-titanium (Ni-Cr-Ti), Group 3: nickel-chromium (Ni-Cr) and Group 4: titanium (Ti). Groups 1, 2 and 3 were in turn subdivided to be melted and cast using: (a) gas oxygen torch and centrifugal casting machine (TC) or (b) induction and centrifugal casting machine (IC). Group 4 was melted and cast using electric arc and vacuum/pressure machine (EV). All of the metal-ceramic crowns were luted with glass-ionomer cement. The marginal fit was measured under an optical microscope before and after cementation using image analysis software. All data was subjected to two-way analysis of variance (ANOVA). Duncans multiple range test was run for post-hoc comparisons. The Students t-test was used to investigate the influence of cementation (α=0.05). RESULTS Uncemented Pd-Au/TC samples achieved the best marginal adaptation, while the worst fit corresponded to the luted Ti/EV crowns. Pd-Au/TC, Ni-Cr and Ti restorations demonstrated significantly increased misfit after cementation. CONCLUSIONS The Ni-Cr-Ti alloy was the most predictable in terms of differences in misfit when either torch or induction was applied before or after cementation. Cemented titanium crowns exceeded the clinically acceptable limit of 120μm. CLINICAL SIGNIFICANCE The combination of alloy composition, melting technique, casting method and luting process influences the vertical seal of cast metal-ceramic crowns. An accurate use of the gas oxygen torch may overcome the results attained with the induction system concerning the marginal adaptation of fixed dental prostheses.

Fracture Load Before and After Veneering Zirconia Posterior Fixed Dental Prostheses.

PURPOSE To evaluate the fracture load of 3-unit zirconia-based posterior fixed dental prostheses (FDPs) before and after veneering the frameworks. MATERIALS AND METHODS Forty standardized stainless-steel master dies were fabricated (height: 5 mm, convergence: 6º, chamfer: 1 mm) and randomly screwed in pairs onto metal bases. The bases were randomly divided into two groups (n = 20 each) according to the zirconia CAD/CAM system used for constructing 3-unit structures for FDPs: group 1 (L): Lava All-ceramic, group 2 (Z): IPS e.max ZirCAD. Half of the zirconia structures per group were randomly selected and veneered, while the remaining half was left unveneered. The specimens were luted in standard fashion onto the stainless steel master dies using conventional glass ionomer cement. All specimens were tested for fracture load (FL). Specimens were subjected to a three-point bending test until fracture by applying an axial compressive load at the central fossa of the pontics with a universal testing machine at a 0.5 mm/min crosshead speed. Wilcoxons rank-sum test and Weibull statistics were used for statistical analysis (α = 0.05). RESULTS L structures recorded significantly higher values of load to fracture than the Z group both before and after veneering. Within each ceramic group, no differences were found between unveneered and veneered frameworks. CONCLUSIONS Although further studies are necessary to corroborate these findings, both zirconia systems could be recommended for restoring posterior teeth on the basis of the fracture load values recorded in this experiment (>1000 N). The veneering procedure did not affect the overall load to fracture in any group.

'Pre-prosthetic use of poly(lactic-co-glycolic acid) membranes treated with oxygen plasma and TiO2 nanocomposite particles for guided bone regeneration processes'.

OBJECTIVES Guided bone regeneration (GBR) processes are frequently necessary to achieve appropriate substrates before the restoration of edentulous areas. This study aimed to evaluate the bone regeneration reliability of a new poly-lactic-co-glycolic acid (PLGA) membrane after treatment with oxygen plasma (PO2) and titanium dioxide (TiO2) composite nanoparticles. METHODS Circumferential bone defects (diameter: 10mm; depth: 3mm) were created on the parietal bones of eight experimentation rabbits and were randomly covered with control membranes (Group 1: PLGA) or experimental membranes (Group 2: PLGA/PO2/TiO2). The animals were euthanized two months afterwards, and a morphologic study was then performed under microscope using ROI (region of interest) colour analysis. Percentage of new bone formation, length of mineralised bone formed in the grown defects, concentration of osteoclasts, and intensity of osteosynthetic activity were assessed. Comparisons among the groups and with the original bone tissue were made using the Kruskal-Wallis test. The level of significance was set in advance at a=0.05. RESULTS The experimental group recorded higher values for new bone formation, mineralised bone length, and osteoclast concentration; this group also registered the highest osteosynthetic activity. Bone layers in advanced formation stages and low proportions of immature tissue were observed in the study group. CONCLUSIONS The functionalised membranes showed the best efficacy for bone regeneration. CLINICAL SIGNIFICANCE The addition of TiO2 nanoparticles onto PLGA/PO2 membranes for GBR processes may be a promising technique to restore bone dimensions and anatomic contours as a prerequisite to well-supported and natural-appearing prosthetic rehabilitations.

Effect of the Nd:YAG laser on sealer penetration into root canal surfaces: a confocal microscope analysis

OBJECTIVES The objective of this in vitro study was to evaluate the use of the Neodymium:Yttrium-Aluminium-Garnet (Nd:YAG) laser as part of the root canal treatment on the penetration of sealer into dentinal tubules. METHODS Eighty extracted lower premolars were randomly assigned to two groups (n=40 each): Control group (CG), subjected to a conventional protocol of endodontic instrumentation and obturation; and Laser group (LG), in which Nd:YAG laser irradiations were combined with conventional preparation and obturation. Endodonted samples were sectioned at 3 and 5 mm from the apex and observed under a confocal scanning microscope (CLSM). The penetration depth into the dentinal tubules and the extension of the intracanal perimeter infiltrated by sealer were measured. The Student-Newman-Keuls test was run for between-group comparisons (α=.05). RESULTS The depth of sealer penetration into dentinal tubules did not differ among groups. LG samples showed the significantly highest percentage of penetrated perimeter at 3 mm from the root apex. Within each group, the greatest depth of penetration (P=.0001), and the major percentage of penetrated perimeter (P<.001), were recorded at 5 mm. CONCLUSIONS The application of the Nd:YAG laser after instrumentation did not improve the depth of sealer penetration into the dentinal tubules. The laser enlarged the total penetrable perimeter near the apex. CLINICAL SIGNIFICANCE The Nd:YAG laser may be an appropriate complement in root canal treatment, as it enhances the sealer adaptation to the dentinal walls in the proximity of the apex.