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.

Evaluation of two interforaminal implants and implant-assisted removable dentures on stress distribution: an in vitro study.

OBJECTIVES: In mandibular edentulism, the treatment option with a two-interforaminal implant-retained bridge and a removable partial denture is rarely evaluated in literature. The aim of this in vitro study was to evaluate the stress distribution of this treatment option by comparing it with traditional treatment options with interforaminal implants in the edentulous mandible. MATERIALS AND METHODS: Two interforaminal implants were placed in a formalin-fixed cadaver mandible, and overdentures with three different types of attachments were fabricated: (1) two ball attachments and an overdenture, (2) a Dolder bar and an overdenture, and (3) screw-retained two-implant inter-canine porcelain fused to a metal bridge and an implant-assisted removable denture (IARD) with precision attachments. Three biting conditions were generated for each denture type, and the strains were documented under vertical loading of 100 N. RESULTS: The calculated strain values from measured strains in all measurement sites and loading conditions for the screw-retained two-implant inter-canine porcelain fused to a metal bridge and a cast framework partial denture with precision attachments situation were lower than in the other scenarios (P<0.05). CONCLUSION: Within the limitations of the present study, it can be concluded that an IARD may be a reasonable and valuable alternative to ball attachments or a bar in two interforaminal implants, especially when the patients prefer to be able to show their teeth even when they take out their removable dentures.

Does Implant-Abutment Interface affect Marginal Bone Levels around Implants?

OBJECTIVE: The use of dental implants with different types of surface roughness and implant-abutment interface has brought about a situation of marginal bone loss. Therefore, the aim of this study was to analyze and compare marginal bone levels of different types of osseointegrated dental implants with platform switch (Group A: Ankylos, Mannheim, Germany) and platform match (Group B: Dentsply Xive, Mannheim, Germany, and Group C: MIS Implant Technologies, Karmiel, Israel). MATERIALS AND METHODS: One hundred and seven patients (52 men and 55 women) with a mean age of 54.79 (standard deviation ± 12.35) years and a total of 321 dental implants (Group A, n = 198; Group B, n = 58; and Group C, n = 65) placed in a private practice between April 2006 and May 2015 were retrospectively analyzed. In addition to demographic information and implant characteristics, marginal bone levels were evaluated by Image J (Wayne Rasband, National Institute of Health, Maryland) program. RESULTS: The mean age of all patients was 54.79 ± 12.35 years, and 51.5% of them were women. Implants supporting fixed bridge were most commonly used in all groups (65%), whereas only 20% were restored with a single crown and 15% with overdentures. In total, 47.5% of all implants showed no marginal bone loss. Mean bone loss in Group A was significantly lower (0.81 ± 1.60 mm) as compared to Group B (1.58 ± 1.59 mm) and Group C (1.18 ± 1.36) (p < 0.005). CONCLUSION: Among different types of dental implants, platform switch seems to preserve marginal bone levels and increase the long-term success of dental implants.

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.

Evaluation of possible prognostic factors for the success, survival, and failure of dental implants.

PURPOSE: To analyze the prognostic factors that are associated with the success, survival, and failure rates of dental implants. MATERIAL AND METHODS: Data including implant sizes, insertion time, implant location, and prosthetic treatment of 1656 implants have been collected, and the association of these factors with success, survival, and failure of implants was analyzed. RESULTS: The success rate was lower for short and maxillary implants. The failure rate of maxillary implants exceeded that of mandibular implants, and the failure rate of implants that were placed in the maxillary anterior region was significantly higher than other regions. The failure rates of implants that were placed 5 years ago or more were higher than those that were placed later. CONCLUSIONS: Anterior maxilla is more critical for implant loss than other sites. Implants in the anterior mandible show better success compared with other locations, and longer implants show better success rates. The learning curve of the clinician influences survival and success rates of dental implants.

In vitro comparison of two different materials for the repair of urethan dimethacrylate denture bases.

PURPOSE: The purpose of this in vitro study was to investigate the flexural properties of a recently introduced urethane dimethacrylate denture base material (Eclipse) after being repaired with two different materials. MATERIALS AND METHODS: Two repair groups and a control group consisting of 10 specimens each were generated. The ES group was repaired with auto-polymerizing polymer. The EE group was repaired with the Eclipse. The E group was left intact as a control group. A 3-point bending test device which was set to travel at a crosshead speed of 5 mm/min was used. Specimens were loaded until fracture occurred and the mean displacement, maximum load, flexural modulus and flexural strength values and standard deviations were calculated for each group and the data were statistically analyzed. The results were assessed at a significance level of P<.05. RESULTS: The mean "displacement", "maximum load before fracture", "flexural strength" and "flexural modulus" rates of Group E were statistically significant higher than those of Groups ES and EE, but no significant difference (P>.05) was found between the mean values of Group ES and EE. There was a statistically significant positive relation (P<.01) between the displacement and maximum load of Group ES (99.5%), Group EE (94.3%) and Group E (84.4%). CONCLUSION: The more economic and commonly used self-curing acrylic resin can be recommended as an alternative repair material for Eclipse denture bases.

The impact of frenulum height on strains in maxillary denture bases.

PURPOSE: The midline fracture of maxillary complete dentures is a frequently encountered complication. The purpose of this study was to assess the effect of frenulum height on midline strains of maxillary complete dentures. MATERIALS AND METHODS: A removable maxillary complete denture was fabricated and duplicated seven times. Four different labial frenulum heights were tested for stresses occurring on the palatal cameo surface. The strains were measured with strain gauges placed on 5 different locations and the stresses were calculated. To mimic occlusal forces bilaterally 100 N of load was applied from the premolar and molar region. RESULTS: A statistically significant association between the height of the labial frenulum and the calculated stresses and strains was shown (P<.05) predominantly on the midline and especially on the incisive papilla. The results showed that stress on the anterior midline of the maxillary complete denture increases with a higher labial frenulum. CONCLUSION: Within the limitations of this in vitro study, it can be concluded that the stress on the anterior midline of the maxillary complete denture increases with a higher labial frenulum. Surgical or mechanical precautions should be taken to prevent short-term failure of maxillary complete dentures due to stress concentration and low cycle fatigue tendency at the labial frenulum region.

Assessment of demographic and clinical data related to dental implants in a group of Turkish patients treated at a university clinic.

PURPOSE: This retrospective study analyzed the distribution of the dental implants with regards to age and gender of the patients and type of indication for the implant therapy, as well as the location, dimension and type of the implants. MATERIALS AND METHODS: The data of demographics (age and gender), type of indication for implant therapy, anatomical location, dimensions (length and diameter) and type (bone and tissue level) of 1616 implants were recorded from patient charts between January 2000 and January 2010. Descriptive statistics were analyzed using a chi-squared test for demographic parameters, type of indication, tooth position, anatomical location, implant dimensions and type (α=.05). RESULTS: The patient pool comprised of 350 women and 266 men, with a mean age of 52.12 ± 13.79 years. The difference in n% of the implants of the age groups was statistically significant between the types of indications. The difference in the position of the implants was statistically significant between the n% of the implants of all age groups. Gender did not significantly vary, except that the diameter of the implants was significantly higher for the standard diameter implants in males. The difference between the implant positions was statistically significant when considered according to indication. The relationship between implant length and anatomical location was statistically significant. CONCLUSION: The indication for dental implant use is age dependent and the type and size of the implant seems to be strongly related to the location of the implant.

The influence of steam cleaning procedures on the surface roughness of commonly used type III dental stone for the fabrication of removable dentures.

OBJECTIVE: This study investigated the possible detrimental effects of steam treatment on the surface of type III dental stone, which is a common laboratory material used for the construction of removable dentures. MATERIAL AND METHODS: Forty dental stone specimens were prepared and divided into four groups (A, B, C and D), and group A was used as the control group. The other groups were treated with steam from a standard distance for varying durations (30, 60 and 120 s). RESULTS: The duration of steam cleaning significantly increased Ra values (F = 63.150, p = 0.000). Similarly, the duration of steam application was directly correlated with the weight changes (F = 17.721, p = 0.000). A significant amount of dental stone can be removed from the surface while treating with steam. CONCLUSION: These studies demonstrated that expanded periods of steam cleaning cause weight loss and abrade the surface of type III dental stones; therefore, these devices should be used with caution during denture fabrication procedures.

Edentulous maxillary arch fixed implant rehabilitation using a hybrid prosthesis made of micro-ceramic-composite: case report.

The prosthetic treatment of patients with an edentulous maxilla opposing mandibular natural teeth is one of the most challenging endeavors that face clinicians. Occlusal forces from the opposing natural teeth may cause fractures in the maxillary prosthesis and also result in advanced bone loss of the edentulous maxilla. With the presence of extreme gagging reflex, the treatment may become more complicated. This article describes and illustrates the 2-stage surgical and prosthetic treatment of a patient with an edentulous maxilla opposing natural teeth. In the beginning, the patient was treated with 4 implants and a maxillary implant-supported overdenture. The extreme gagging reflex and the occlusal forces from the mandibular natural teeth obligated the team a second stage surgical and prosthetic treatment, which included increasing the number of implants after bilateral sinus lifting in the posterior maxilla and fabricating a maxillary fixed hybrid prosthesis made of micro-ceramic composite that yielded a satisfactory result.

The influence of implant number and attachment type on maximum bite force of mandibular overdentures: a retrospective study.

AIM: Assessment of the influence of such factors as attachment type, number of implants, gender and age of patients on maximum bite force (MBF). MATERIAL AND METHODS: Sixty-two edentulous patients (32 females, 30 males; aged 64.03 ± 10.07 years, range 42-90 years) with mandibular implant overdentures with various attachment types were included in the study and their MBFs were recorded. The results were evaluated statistically at a significance level of p < 0.05. RESULTS: The MBF in male patients was found to be statistically significantly (p < 0.05) higher than in female patients. No statistically significant differences (p > 0.05) were found with respect to age groups, attachment types and number of implants supporting the mandibular overdentures. CONCLUSION: Within the limitations of this study, it is concluded that independent of the number applied, dental implants increase MBF in edentulous patients. While males show higher bite force, patient age and attachment type seem not to play an important role.

Flexural properties of a light-cure and a self-cure denture base materials compared to conventional alternatives.

PURPOSE: A new light curing urethane dimethacrylate and a cold curing resin with simpler and faster laboratory procedures may have even improved flexural properties. This study investigated the 3-point flexural strengths and flexural moduli of two alternate base materials. MATERIALS AND METHODS: A cold curing resin (Weropress) and a light curing urethane dimethacrylate base material (Eclipse). Along with Eclipse and Weropress, a high impact resin (Lucitone199) and three conventional base materials (QC 20, Meliodent and Paladent 20) were tested. A 3-point bending test was used to determine the flexural strengths and flexural moduli. The mean displacement, maximum load, flexural modulus and flexural strength values and standard deviations for each group were analyzed by means of one-way analysis of variance (ANOVA) (with mean difference significant at the 0.05 level). Post hoc analyses (Scheffe test) were carried out to determine the differences between the groups at a confidence level of 95%. RESULTS: Flexural strength, displacement and force maximum load values of Eclipse were significantly different from other base materials. Displacement values of QC 20 were significantly different from Lucitone 199 and Weropress. CONCLUSION: The flexural properties and simpler processing technique of Eclipse system presents an advantageous alternative to conventional base resins and Weropress offers another simple laboratory technique.

Impression procedures and construction of a sectional denture for a patient with microstomia: a clinical report.

This article describes a modified impression procedure and a method of fabricating a 2-piece collapsible denture for a patient with limited oral opening as a result of the resection of a precancerous lesion on the maxillary lip. Fabricating the denture in 2 pieces (a smaller anterior piece and a larger, hinged, collapsible posterior piece) enabled the patient to place and remove the denture.