Faculty Bibliography

BACKGROUND: Dental literature has limited number of publications regarding long-term outcome data of immediate restoration of single missing teeth with an implant-supported provisional crown. PURPOSE: This 5-year study evaluated hard and soft tissue responses to the immediate placement of single implant-supported provisional crowns. MATERIALS AND METHODS: Twenty patients received one dental implant restored immediately with a provisional acrylic resin screw-retained crown. Crestal bone loss was evaluated from standardized periapical radiographs collected at 3-month intervals for the first 21 months followed by a 5-year evaluation. Historical controls acquired from available dental literature were used for comparison. RESULTS: One implant failed within 2 months of surgical placement, presenting with pain and mobility. The remaining implants demonstrated no infection, pain, or radiolucencies. Nineteen implants were clinically immobile, osseointegrated, and asymptomatic at 21 months. At 5 years, one patient died, three patients were noncompliant, and 15 implants were evaluated as functional. Mean bone loss (MBL) at 1 year and 21 months was approximately 0.5 +/- 0.5 mm and 0.70 +/- 0.26 mm at 5 years. There was no statistically significant difference between MBLs at p < 0.05. CONCLUSIONS: Immediate provisionalization of single dental implants compares favorably with conventional loading protocols. Long-term data suggest that immediate provisionalization of single dental implants is a viable treatment option.

Implant failure is more likely to occur in persons with medically compromising systemic conditions, such as diabetes related to high blood glucose levels and inflammatory diseases related to pH levels lower than those in healthy people. The aim of this study was to investigate the effects of lower pH level and simulated- hyperglycemia on implant corrosion as these effects are critical to biocompatibility and osseointegration. The electrochemical corrosion properties of titanium implants were studied in four different solutions: Ringer's physiological solution at pH = 7.0 and pH = 5.5 and Ringer's physiological solution containing 15 mM dextrose at pH = 7 and pH = 5.5. Corrosion behaviors of dental implants were determined by cyclic polarization test and electrochemical impedance spectroscopy. Surface alterations were studied using a scanning electron microscope. All test electrolytes led to apparent differences in corrosion behavior of the implants. The implants under conditions of test exhibited statistically significant increases in I(corr) from 0.2372 to 1.007 muAcm(-2), corrosion rates from 1.904 to 8.085 mpy, and a decrease in polarization resistances from 304 to 74 Omega. Implants in dextrose-containing solutions were more prone to corrosion than those in Ringer's solutions alone. Increasing the acidity also yielded greater corrosion rates for the dextrose-containing solutions and the solutions without dextrose.

BACKGROUND: Although, dental implants have been a predictable option to support several types of restorations, mechanical problems are not uncommon. Retaining and abutment screw loosenings/fractures are one of the most common technical problems. AIM: To present a step-by-step technique in order to remove a broken locater abutment screw fragment. MATERIALS AND METHODS: A 56-year-old, edentulous man with a fractured locator abutment screw in an implant was referred to our clinic from a private practice. His dentist placed a narrow platform locator abutment onto a regular platform implant and the fracture occurred. Attempts to remove the fractured fragment using a periodontal probe and a manual screw removal driver were unsuccessful. RESULTS: This clinical report presents a situation in which a fractured locater abutment screw fragment was successfully removed using an implant repair kit. CONCLUSION: A fractured locater abutment screw fragment was successfully removed using an implant repair kit including drills, drill guides and tapping instruments. To avoid similar complications, it is recommended to use appropriate manufacturer specified torque values in conjunction with compatible restorative components. CLINICAL SIGNIFICANCE: Retaining and abutment screw loosenings/fractures are one of the most common mechanical problems associated with the implant components. This clinical report showed how to remove a broken screw fragment using proper armamentarium and technique, which might help clinicians eliminate similar problems.

PURPOSE: To evaluate the effect of various metal oxides on impact strength (IS), fracture toughness (FT), water sorption (WSP) and solubility (WSL) of heat-cured acrylic resin. MATERIALS AND METHODS: Fifty acrylic resin specimens were fabricated for each test and divided into five groups. Group 1 was the control group and Group 2, 3, 4 and 5 (test groups) included a mixture of 1% TiO2 and 1% ZrO2, 2% Al2O3, 2% TiO2, and 2% ZrO2 by volume, respectively. Rectangular unnotched specimens (50 mm x 6.0 mm x 4.0 mm) were fabricated and droptower impact testing machine was used to determine IS. For FT, compact test specimens were fabricated and tests were done with a universal testing machine with a cross-head speed of 5 mm/min. For WSP and WSL, discshaped specimens were fabricated and tests were performed in accordance to ISO 1567. ANOVA and Kruskal-Wallis tests were used for statistical analyses. RESULTS: IS and FT values were significantly higher and WSP and WSL values were significantly lower in test groups than in control group (P<.05). Group 5 had significantly higher IS and FT values and significantly lower WSP values than other groups (P<.05) and provided 40% and 30% increase in IS and FT, respectively, compared to control group. Significantly lower WSL values were detected for Group 2 and 5 (P<.05). CONCLUSION: Modification of heat-cured acrylic resin with metal oxides, especially with ZrO2, may be useful in preventing denture fractures and undesirable physical changes resulting from oral fluids clinically.

By using traditional casting procedures, accurately fitting of complete-arch frameworks that are screwed on multiple implants is difficult to achieve. The introduction of computer-aided design and manufacturing (CAD/CAM) techniques for fabricating custom 1-piece titanium frameworks simplifies this challenge and reduces time spent by the restorative dentist. This report presents a milled titanium complete-arch mandibular framework using a new planning software and a new scanner using non-contact laser probe, which eliminates the need for wax pattern fabrication.

STATEMENT OF PROBLEM: To achieve functional and esthetic results, implants must be placed accurately. However, little information relating to the effect of operator experience on implant placement accuracy is available. PURPOSE: The objective of this investigation was to measure the accuracy of dental implant placement with a bone-supported stereolithographic surgical template created from a virtual implant plan and to determine the effect of operator experience on implant placement accuracy. MATERIAL AND METHODS: Twenty photopolymer resin edentulous mandibles were scanned with cone beam computerized tomography (CBCT). Five implants were planned virtually for each mandible, and a stereolithographic surgical template was made. Four operators placed a total of 100 implants (25 per operator). Two of the operators were experienced in implant placement and 2 operators had limited prior implant placement experience. A CBCT scan of the postimplant placement mandibles was performed, and the images were superimposed on the preimplant placement images containing the virtual implant plans. The amount of angular, horizontal, and vertical deviation of the placed implants from the virtually planned implants at the apex and platform was calculated, and statistically significant differences were detected between the operator groups by using a multivariate analysis of variance (MANOVA) (alpha=.05). RESULTS: For the experienced operators, the mean error of angular deviation was 2.60 +/-1.25 degrees, of horizontal deviation at the apex 0.34 +/-0.15 mm, of horizontal deviation at the platform 0.63 +/-0.28 mm, of vertical deviation at the apex 0.59 +/-0.12 mm, and of vertical deviation at the platform 0.16 +/-0.11 mm. For the inexperienced group, the mean error of angular deviation was 3.96 +/-1.64 degrees, of horizontal deviation at the apex 0.42 +/-0.19 mm, of horizontal deviation at the platform 0.77 +/-0.33 mm, of vertical deviation at the apex 0.62 +/-0.13 mm, and of vertical deviation at the platform 0.15 +/-0.11 mm. The MANOVA showed a statistically significant difference between the experienced and inexperienced groups for angular and horizontal error at the implant apex and platform (P<.05). CONCLUSIONS: The results of this in vitro investigation revealed that the experience level of the operator placing the implants contributes to the accuracy of implant placement, with more experienced operators placing more implants accurately.

STATEMENT OF PROBLEM: The fabrication of an accurately fitting implant-supported fixed prosthesis requires multiple steps, the first of which is assembling the impression coping on the implant. An imprecise fit of the impression coping on the implant will cause errors that will be magnified in subsequent steps of prosthesis fabrication. PURPOSE: The purpose of this study was to characterize the 3-dimensional (3D) precision of fit between impression coping and implant replica pairs for 3 implant systems. The selected implant systems represent the 3 main joint types used in implant dentistry: external hexagonal, internal trilobe, and internal conical. MATERIAL AND METHODS: Ten impression copings and 10 implant replicas from each of the 3 systems, B (Branemark System), R (NobelReplace Select), and A (NobelActive) were paired. A standardized aluminum test body was luted to each impression coping, and the corresponding implant replica was embedded in a stone base. A coordinate measuring machine was used to quantify the maximum range of displacement in a vertical direction as a function of the tightening force applied to the guide pin. Maximum angular displacement in a horizontal plane was measured as a function of manual clockwise or counterclockwise rotation. Vertical and rotational positioning was analyzed by using 1-way analysis of variance (ANOVA). The Fisher protected least significant difference (PLSD) multiple comparisons test of the means was applied when the F-test in the ANOVA was significant (alpha=.05). RESULTS: The mean and standard deviation for change in the vertical positioning of impression copings was 4.3 +/-2.1 mum for implant system B, 2.8 +/-4.2 mum for implant system R, and 20.6 +/-8.8 mum for implant system A. The mean and standard deviation for rotational positioning was 3.21 +/-0.98 degrees for system B, 2.58 +/-1.03 degrees for system R, and 5.30 +/-0.79 degrees for system A. The P-value for vertical positioning between groups A and B and between groups A and R was <.001. No significant differences were found for vertical positioning between groups B and R. The P-value for rotational positioning between groups A and B and between groups A and R was <.001. No significant differences were found for rotational positioning between groups B and R. CONCLUSIONS: The results of the study confirmed that implant systems differ in precision of fit. Vertical precision between paired implant components is a function of joint type and the tightening force applied to the guide pin. The magnitude of vertical displacement with applied torque is greater for conical connections than for butt joint connections. The rotational freedom between paired components is unique to the implant system and is presumably related to the machining tolerances specified by the manufacturer.

PURPOSE: To evaluate the primary stability of 1-stage (nonsubmerged) and 2-stage (submerged) implants via newest wireless resonance frequency (RF) analyzer and newer wireless mobility measuring (MM) device. MATERIALS AND METHODS: Six 1-stage dental implants with internal hex connection and six 2-stage dental implants, 4.1 mm in diameter and 11.5 mm in length, were inserted bilaterally into the first premolar, second premolar, and first molar regions of 6 standard mandibular transparent self-curing acrylic resin models. After that, the periimplant circular bone defects were created in millimeter increments ranging between 0 and 5 mm to the same extent on all implants. RESULTS: Implant stability quotient values significantly decreased at 1-stage and 2-stage implants when periimplant defects increased. Similar implant stability quotient values were found for both implant types; however, significantly lower MM values were noted for 2-stage implants. Irrespective of implant systems, the results indicated a significant association between wireless RF analyzer and wireless MM device. CONCLUSION: Both wireless RF analyzer and wireless MM device were adequate in assessing implant stability. There was no difference between 2-stage and 1-stage implant systems, except lower MM values were noted for nonsubmerged implants.

STATEMENT OF PROBLEM: Precise treatment planning before implant surgery is necessary to identify vital structures and to ensure a predictable restorative outcome. PURPOSE: The purpose of this study was to compare the accuracy of implant placement by using 3 different types of surgical guide: bone-supported, tooth-supported, and mucosa-supported. MATERIAL AND METHODS: Thirty acrylic resin mandibles were fabricated with stereolithography (SLA) based on data from the cone beam computerized tomography (CBCT) scan of an edentulous patient. Ten of the mandibles were modified digitally before fabrication with the addition of 4 teeth, and 10 of the mandibles were modified after fabrication with soft acrylic resin to simulate mucosa. Each acrylic resin mandible had 5 implants virtually planned in a 3-D software program. A total of 150 implants were planned and placed by using SLA guides. Presurgical and postsurgical CBCT scans were superimposed to compare the virtual implant placement with the actual implant placement. For statistical analyses, a linear mixed models approach and t-test with the 2-sided alpha level set at .016 were used. All reported P values were adjusted by the Dunn-Sidak method to control the Type I error rate across multiple pairwise comparisons. RESULTS: The mean angular deviation of the long axis between the planned and placed implants was 2.2 +/-1.2 degrees; the mean deviations in linear distance between the planned and placed implants were 1.18 +/-0.42 mm at the implant neck and 1.44 +/-0.67 mm at the implant apex for all 150 implants. After the superimposition procedure, the angular deviation of the placed implants was 2.26 +/-1.30 degrees with the tooth-supported, 2.17 +/-1.02 degrees with the bone-supported, and 2.29 +/-1.28 degrees with the mucosa-supported SLA guide. The mean deviations in linear distance between the planned and placed implants at the neck and apex were 1.00 +/-0.33 mm and 1.15 +/-0.42 mm for the tooth-supported guides; 1.08 +/-0.33 mm and 1.53 +/-0.90 mm for the bone-supported guides; and 1.47 +/-0.43 mm and 1.65 +/-0.48 mm for the mucosa-supported SLA surgical guides. CONCLUSIONS: The results of this study show that stereolithographic surgical guides may be reliable in implant placement and that: 1) there was no statistically significant difference among the 3 types of guide when comparing angular deviation and 2) mucosa-supported guides were less accurate than both tooth-supported and bone-supported guides for linear deviation at the implant neck and apex.