Comparison of denture base adaptation between additive and conventional fabrication techniques.

PURPOSE: This in vitro study compared the adaptation of denture bases fabricated by injection molding (IM), compression molding (CM), liquid crystal display (LCD), and digital light processing (DLP) techniques. MATERIAL AND METHODS: A definitive maxillary cast was duplicated using a silicone mold to create 40 gypsum casts that were laser scanned before any fabrication procedures were initiated. For the DLP and LCD groups, 20 denture bases (10 in each group) were virtually designed and manufactured referring to the digitalized data. For the CM and IM groups, 20 denture bases (10 in each group) were molded using gypsum models. A total of 40 gypsum models and their corresponding denture bases were scanned. The scanned intaglio surface of each denture base was superimposed on the scanned reference cast to compare the degree of tissue surface adaptation. The three-dimensional surface deviations of the total intaglio surface, denture border apex, palatal vault, and crest of the ridge were evaluated on the basis of the best fit algorithm technique using inspection software. The data were statistically analyzed using one-way ANOVA and Tukey's multiple comparison test (α = 0.05). RESULTS: According to the superimposing results, for the total intaglio surface, the lowest deviation was present on the injection-molded group and the highest deviation occurred on the LCD group. For the palatal vault, the lowest deviation was present on the DLP group and the highest deviation occurred in the compression molded group. For the crest of the ridge, the lowest deviation was present in the injection-molded group and the highest deviation occurred in the LCD group. For the denture border apex, the lowest deviation was present in the DLP group and the highest deviation occurred in the LCD group. CONCLUSIONS: Maxillary denture bases fabricated using DLP and IM techniques showed higher surface adaptation than the bases fabricated using LCD and CM techniques. Among the conventional techniques, higher compatible dentures can be produced with IM; among the additive techniques, higher compatible dentures can be produced with DLP.

Is Resonance Frequency Analysis a Reliable Evaluation for Primary Stability of Implants Without Apical Contact?

PURPOSE: The primary stability of dental implants is one of the most crucial factors for providing long-term success of osseointegration. Vertical deficiencies, such as those due to maxillary sinus pneumatization, may cause a severe vertical limitation to residual bone height. This study aimed to examine the primary stabilization of implants without apical contacts. MATERIALS AND METHODS: Eighty bone-level implants (4.1-mm diameter/10-mm length) were placed into polyurethane test blocks without apical contacts. According to coronal bone-to-implant contact, groups were set as 4, 6, 8, and 10 mm, respectively. Resonance frequency analysis (RFA) using a SmartPeg was performed separately toward the transversal and horizontal axes by two independent researchers. Data were statistically compared for interobserver and among groups. RESULTS: Interobserver reliability varied from moderate to excellent (intraclass correlation coefficient [ICC]: 0.629 to 0.985). There were no significant differences among the 6 mm, 8 mm, and 10 mm groups, although the 4 mm group showed the significantly lowest stability (P < .001). Transversal and longitudinal measurements of the same groups did not show a parallel correlation statistically. CONCLUSION: RFA values may be affected by the finger torque in tightening of the SmartPeg among different researchers. Fully placed implants did not significantly show the highest stability among various apically contactless groups. Consequently, RFA should not be used alone to evaluate primary stability for implants without an apical contact.

Accuracy of 14 intraoral scanners for the All-on-4 treatment concept: a comparative in vitro study.

PURPOSE: This in vitro study aimed to evaluate the accuracy of 14 different intraoral scanners for the All-on-4 treatment concept. MATERIALS AND METHODS: Four implants were placed in regions 13, 16, 23, and 26 of an edentulous maxillary model that was poured with scannable Type 4 gypsum to imitate the All-on-4 concept. The cast was scanned 10 times for each of 14 intraoral scanners (Primescan, iTero 2, iTero 5D, Virtuo Vivo, Trios 3, Trios 4, CS3600, CS3700, Emerald, Emerald S, Medit i500, BenQ BIS-I, Heron IOS, and Aadva IOS 100P) after the polyether ether ketone scanbody was placed. For the control group, the gypsum model was scanned 10 times with an industrial scanner. The first of the 10 virtual models obtained from the industrial model was chosen as the reference model. For trueness, the data of the 14 dental scanners were superimposed with the reference model; for precision, the data of all 14 scanners were superimposed within the groups. Statistical analyses were performed using the Kolmogorov-Smirnov, Shapiro-Wilks, and Dunn's tests. RESULTS: Primescan showed the highest trueness and precision values (P < .005), followed by the iTero 5D scanner (P < .005). CONCLUSION: Some of these digital scanners can be used to make impressions within the All-on-4 concept. However, the possibility of data loss due to artifacts, reflections, and the inability to combine the data should be considered.

Primary Stability in Various Levels of Impacted Implants: An Ex Vivo Study.

The aim of this study was to examine the primary stabilization of different vertically impacted bone implants. Implant stability was measured by resonance frequency analysis. Forty-five dental implants were used and divided into 3 groups. Group 1 was placed 4 mm (1/3 impacted), group 2 was placed 8 mm (2/3 impacted), and group 3 was placed 12 mm (fully impacted). Implant stability quotient values were measured on the longitudinal and transversal axis by 2 independent researchers. The fully impacted group showed the significantly highest value among the groups (P < .05). There were statistically varying implant-stability quotient values between researchers. None of the 1/3-impacted implants' value reached a 70 implant-stability quotient value.

In vitro comparison of trueness of 10 intraoral scanners for implant-supported complete-arch fixed dental prostheses.

STATEMENT OF PROBLEM: Digital scanning systems have become popular, but whether these systems are adequate for complete-arch implant-supported fixed dental prostheses is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the trueness of 10 different dental intraoral scanners. MATERIAL AND METHODS: Six implant analogs were installed, and an edentulous mandibular model composed of scannable Type 4 gypsum was scanned with 10 different intraoral scanners (3D Progress, Omnicam, Bluecam, Apollo DI, Planscan, E4D Tech, TRIOS MonoColor Cart, TRIOS Color Cart, TRIOS Color Pod, Lythos), 10 times each after the scan body was placed on the implant abutments. The data obtained were then converted into standard tessellation language format. For the control group, the gypsum model was scanned with an industrial scanner (ATOS Core 80). For trueness, the dental and industrial scanning data packs were analyzed with 3D comparison software. Statistical analyses were performed by using the Kruskal-Wallis and Mann-Whitney U tests. RESULTS: When ranked according to their surface superimposition values, the Color POD, Omnicam, Apollo DI, Color Cart, MonoColor Cart, and Bluecam scanners were found within the range of 31 to 45 µm. This group was followed by E4D, 3D Progress, Lythos, and Planscan, which were found within the range of 82 to 344 µm according to the same criteria. CONCLUSIONS: Some of the digital scanners had the necessary performance for the fabrication of complete-arch implant-supported fixed dental prostheses. However, the possibility of data loss producing artifacts should be considered.

Effect of different polishing techniques for composite resin materials on surface properties and bacterial biofilm formation.

OBJECTIVES: Both direct and indirect techniques are used for composite resin material (CRM) restorations. Polishing processes are needed in both techniques after intraoral adjustment. However, it is unclear as to which polishing technique should be preferred with respect to decreasing biofilm. The purpose of thisin vitro study was to evaluate the surface properties and Streptococcus mutans biofilm formation on direct and indirect CRMs after using different polishing techniques. METHODS: Two CRMs (direct and indirect) and four polishing techniques (aluminium oxide discs, diamond polishing paste, aluminium oxide polishing paste, and silicon carbide brush) were evaluated. The specimens were prepared for taking scanning electron microscopy images (n = 2) and determining surface roughness, surface free energy, and bacterial biofilm formation (BBF) with colony-forming unit counting and confocal laser scanning microscopy assays (n = 7). The data were analysed using two-way analysis of variance with Bonferroni as a post hoc test and Pearson's correlation (p < .05). RESULTS: The surface roughness values in the control group were higher than those in the diamond polishing paste group (p = 0.025), but the values in the aluminium oxide polishing paste and silicon carbide brush groups were comparable with those in the control group (p =  0.156 and p =  1.000, respectively). The highest surface free energy values were recorded in the silicon carbide brush group (p < 0.001), whereas there were no differences found among the other groups (p > 0.05). The highest BBF was seen in the silicon carbide brush (p <  0.001) and direct CRM (p < 0.001) groups. CONCLUSION: BBF on the surface of direct CRMs differed from that on indirect CRMs after polishing the surface. The tested polishing techniques significantly influenced surface properties and BBF. CLINICAL SIGNIFICANCE: In situations that require the intraoral adjustment of CRMs, polishing with a diamond polishing paste seems to be a good option to polish the surface of both direct and indirect CRMs because the diamond polishing paste results better in terms of decreasing biofilm formation and improving surface properties.

Comparison of the Primary Stability of Two Implant Designs in Two Different Bone Types: An In Vitro Study.

PURPOSE: Achievement of primary stability upon surgical placement of dental implants is a key factor for successful osseointegration and depends mainly on implant-related factors. The aim of this study was to compare and assess the primary stability of implants with active and regular threads in type 2 as well as type 4 bone. MATERIALS AND METHODS: Fresh cow vertebrae and a pelvis were used as models of type 4 bone and type 2 bone, respectively. Implants with two different designs-regular-threaded and active-threaded-both 4.3 mm wide and 13 mm long, were placed in both types of bone (n = 80). Stability measurements were completed by four prosthodontists using two different Periotest devices and resonance frequency analysis. Statistical analyses were performed with the Mann-Whitney U test. RESULTS: No statistically significant differences were found between the implant types in either type of bone in the stability measured with different methods. For both implant types, the mean resonance frequency values in type 2 bone were statistically significantly higher than in type 4 bone, whereas the mean Periotest values in type 2 bone were statistically significantly lower than in type 4 bone. CONCLUSION: Within the limitations of this in vitro study in bone types 2 and 4, the active-threaded implant, which was invented to increase primary stability, did not show higher primary stability compared to a regular-threaded implant.

Determination of the Optimum Torque to Tighten the Smartpegs of Magnetic Resonance Frequency Analyses Devices: An Ex Vivo Study.

The aim of this study was to find an optimal value for tightening the Smartpegs for magnetic radiofrequency analysis devices (RFAs) devices. Thirty implants were placed in 3 cow ribs. The RFA value of each implant was measured in buccal and mesial directions after tightening the Smartpegs with 1, 3, 4, 8, 9, 10, and 11 Ncm. Additionally, 4 different examiners measured the RFA after hand tightening the Smartpegs, and the results were compared. The buccal implant stability quotient (ISQ) values when the Smartpegs were tightened to 1Ncm were significantly lower than the ISQ values when the Smartpegs were tightened to 3, 4, 8, 9, 10, and 11 Ncm (P < .05). The mesial ISQ values when the Smartpegs were tightened to 1, 3, and 4 Ncm were significantly lower than the ISQ values when the Smartpegs were tightened with higher torque values (P < .05). The buccal measurements made by 1 examiner was significantly lower than 3 Ncm (P < .05), and the buccal measurements made by 1 examiner was significantly lower than 4 Ncm (P < .05). The mesial ISQ values measured by 2 examiners were significantly lower than 3 Ncm (P < .05), and the mesial ISQ values measured by the other 2 examiners were significantly lower than 8 Ncm (P < .05). The tightening of the Smartpegs should be standardized by the manufacturer to a range of 5-8 Ncm in order to gain reliable objective RFA values, instead of leaving it to subjective finger pressure.

The influence of interimplant distance in mandibular overdentures supported by two implants on patient satisfaction and quality of life.

This study evaluates the influence of interimplant distance (ID) on patient satisfaction and quality of life (QOL) of 55 patients who received mandibular overdentures supported by two implants. IDs were measured over the residual ridge crest and linearly on all of the patients' mandibular casts. The crestal detours of all patients were determined by subtracting these two values from each other. Higher IDs were associated with better QOL scores (P < .05), whereas higher crestal detour values were associated with better general comfort, chewing, ease of hygiene maintenance, esthetics, pain, and QOL scores (P < .05).

The influence of momentary retention forces on patient satisfaction and quality of life of two-implant-retained mandibular overdenture wearers.

PURPOSE: The purpose of this study was to assess the influence of momentary retention forces on patient satisfaction and quality of life of two-implant-retained mandibular overdenture wearers. MATERIALS AND METHODS: Edentulous patients who had been rehabilitated with two-implant-supported mandibular overdentures with single attachments and maxillary complete dentures at a university clinic were included in this study. The overdenture attachments were either ball or locator attachments. All the patients completed the Turkish version of the Oral Health Impact Profile-14 (OHIP-14) and the visual analog scale (VAS) satisfaction questionnaires. Momentary retention forces of the overdentures were measured using a custom-made dynamic testing machine. RESULTS: Fifty-five patients were included in this study. No statistically significant association was detected between momentary retention forces and VAS scores (P > .05), but higher retention forces presented significantly better quality of life scores in the social disability and handicap domains of OHIP-14 (P < .05). CONCLUSION: Within the limitations of this clinical study, it may be presumed that although higher instant retention force of an implant-retained overdenture provides better quality of life, it does not affect patient satisfaction.

The Evaluation of the Reliability of Periotest for Implant Stability Measurements: An In Vitro Study.

Periotest (Medizintechnik Gulden, Modautal, Germany) is a widely accepted implant stability measurement method, although the reliability is not well known. The aim of this in vitro study was to investigate the reliability of the Periotest in implant stability measurements. Thirty implants were placed in 3 cow ribs. The stability of each implant was measured by insertion torque, resonance frequency analyses, and Periotest and then compared. The Periotest values (PTVs) were measured by 4 different examiners. The measurements were repeated twice in both the buccal and mesial directions, for each implant at 2-hour intervals and the intra- and interobserver reliability of Periotest was measured. Results showed that the intraobserver reliability of the Periotest was excellent for the buccal PTVs but fair to poor for the mesial PTVs. The interobserver reliability of the Periotest was excellent for the buccal PTVs but poor for the mesial PTVs. No significance was found between the PTVs and IT values (P = .803) and PTVs and ISQ values, whereas a 47.1% significant correlation was detected between the IT values and ISQ values (P = .009). The present study indicates that only Periotest measurements from buccal result in excellent intra- and interobserver reliability for the quantification of the implant stability.

Comparative ex vivo evaluation of two electronic percussive testing devices measuring the stability of dental implants.

BACKGROUND: A comparative ex vivo study was performed to determine electronic percussive test values (PTVs) measured by cabled and wireless electronic percussive testing (EPT) devices and to evaluate the intra- and interobserver reliability of the wireless EPT device. METHODS: Forty implants were inserted into the vertebrae and forty into the pelvis of a steer, a safe distance apart. The implants were all 4.3 mm wide and 13 mm long, from the same manufacturer. PTV of each implant was measured by four different examiners, using both EPT devices, and compared. Additionally, the intra- and interobserver reliability of the wireless EPT device was evaluated. RESULTS: Statistically significant differences (P <0.05) were observed between PTVs made by the two EPT devices. PTVs measured by the wireless EPT device were significantly higher than the cabled EPT device (P <0.05), indicating lower implant stability. The intraobserver reliability of the wireless EPT device was evaluated as excellent for the measurements in type II bone and good-to-excellent in type IV bone; interobserver reliability was evaluated as fair-to-good in both bone types. CONCLUSION: The wireless EPT device gives PTVs higher than the cabled EPT device, indicating lower implant stability, and its inter- and intraobserver reliability is good and acceptable.

Maintenance requirements associated with mandibular implant overdentures: clinical results after first year of service.

The aim of this clinical study was to evaluate the prosthodontic maintenance requirements during the first year of service of mandibular overdentures supported by interforaminal implants and to assess the influence of attachment type, implant number, and bite force on these requirements. Fifty-nine patients treated with mandibular implant overdentures between the years 2004 and 2009 and appearing in the 12th-month recall were included in this study. The overdentures constituted 4 groups: 2 single interforaminal implants (1 group with locator and 1 group with ball attachments), 3 single interforaminal implants, 3 splinted interforaminal implants (bar), and 4 splinted interforaminal implants (bar). During the examination, prosthetic parameters such as occlusion, tissue adaptation, condition of the retentive mechanism (matrice and patrice), and the condition of the denture-bearing tissues were evaluated and recorded. No statistically significant relation was found between attachment type, bite force values, implant number, and the occurring complications except the need for relining, which was found significantly more in the ball attachments than in other attachment groups (P  =  .03). After 12 months following the overdenture insertion, there seems to be no relation between occurring complications and patient-related factors, such as maximum bite force, age, and gender, as well as factors related to the overdentures such as number and type of attachments.