Effect of scan pattern on the scan accuracy of a combined healing abutment scan body system.

STATEMENT OF PROBLEM: A recently introduced scan body combined with a contoured healing abutment enables digital scans of the implant while its healing abutment shapes the soft tissue for an appropriate emergence profile. However, information on the effect of different scan patterns on the scan accuracy of this new system is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the effect of scan pattern on the accuracy of digital implant scans by using a combined healing abutment-scan body system. MATERIAL AND METHODS: A combined healing abutment-scan body system was secured on a single implant at the right first molar site in a dentate mandibular model. A master reference model was generated by scanning the model with an industrial light scanner. The model was then scanned with 4 different scan patterns (SP-A, SP-B, SP-C, and SP-D) by using an intraoral scanner (TRIOS 3). Test scans (n=8) were superimposed over the master reference model by using a metrology software, and distance and angular deviations were calculated. Distance and angular deviation data were analyzed with a multivariate analysis of variance and the Tukey honestly significant difference tests for trueness and precision (α=.05). RESULTS: Distance deviations (trueness [P=.461] and precision [P=.533] deviations) in the scans were not significantly affected by the scan pattern. Scan pattern affected the trueness (P=.001) and precision (P=.002) when angular deviations were considered. In terms of trueness, SP-D resulted in the highest angular deviations in scans (P≤.031), while the difference in deviations in scans obtained by using other scan patterns was not significant (P≥.378). When angular deviation data were considered, SP-D resulted in lower scan precision than SP-A (P=.014) and SP-B (P=.007). The precision of scans using SP-C was similar to the precision of the scans made by using other scan patterns (P≥.055) in terms of angular deviations. CONCLUSIONS: The scan accuracy of a combined healing abutment-scan body system was affected by the scan pattern. The scans performed with SP-D presented the lowest accuracy considering the angular deviation data and, therefore, may be the least favored among the patterns tested for scanning a combined healing abutment-scan body system.

Effect of Scanner Type and Scan Body Location on the Accuracy of Mandibular Complete-Arch Digital Implant Scans: An In Vitro Study.

PURPOSE: To compare the accuracy (trueness and precision) of scans of a newly introduced intraoral scanner (IOS) (Virtuo Vivo) and a widely used IOS (Trios 3) to a laboratory scanner (LBS) (Cares 7 SERIES) for 6 implants placed in an edentulous mandible, and to investigate the effect of scan body location on trueness. MATERIAL AND METHODS: Scanbodies were tightened on 6 implants placed in an edentulous polymethylmethacrylate mandibular model. An industrial scanner was utilized to generate a master reference model STL file. Three different scanners were used to scan the model (2 IOSs and 1 LBS), and the scans (n = 10) were exported into STL files. Best-fitting algorithm was used to superimpose test scans over the MRM-STL (nominal). ANOVA and Tukey HSD tests were performed to analyze the data (α = 0.05). RESULTS: The distance deviations in Car7-LBS scans were the highest (p < 0.001), whereas those in Tri-IOS scans were the lowest (p < 0.001). Vir-IOS had lower angular deviations than those of Tri-IOS (p = 0.031). In Vir-IOS scans, SB5 had higher distance deviations than SB2 (p = 0.029) and SB3 (p = 0.044). In Car7-LBS scans, SB1 had higher distance deviations than SB3 (p = 0.015) and SB5 (p = 0.005). In Tri-IOS scans, SB1 had higher mean distance deviations than SB2 and SB5 (p = 0.005). Vir-IOS had lower precision than Car7-LBS (distance deviation data) (p = 0.01). No difference was found among scanners for the precision of angular deviation data (p = 0.840). CONCLUSION: When trueness and precision were considered, distance and angular deviations depended on the scanner type. None of the scanners outperformed others in accuracy considering all distance and angular deviations. Scan body location affected only the trueness (distance deviations).

Accuracy of Different Complete-Arch Digital Scanning Techniques with a Combined Healing Abutment-Scan Body System.

PURPOSE: Investigate the effects of three different complete-arch digital implant scanning techniques used with a combined healing abutment-scan body (CHA-SB) system on the accuracy (trueness and precision) and scan time. MATERIALS AND METHODS: A poly(methyl methacrylate) master model simulating an edentulous maxilla was fabricated with four parallelly inserted dental implants. A CHA-SB system was attached to each implant. The model surface was scanned using a structured blue light industrial extraoral scanner to achieve a reference model standard tessellation language file (MRM-STL). Three different scanning techniques-(1) conventional technique with unmodified master model, (2) scan body splinting technique using orthodontic elastic ligatures and plastic splint materials, and (3) land-marking technique using pyramid-shaped glass-ceramic markers-were performed. Fourteen consecutive digital scans were made by using an intraoral scanner (IOS) for each technique, converted to an STL file, and superimposed on the MRM-STL. Trueness and precision were calculated for each technique. The scan time was also recorded. The data were analyzed with one-way analysis of variance (ANOVA) and Tukey honest significant difference (HSD) tests (α = .05). RESULTS: Effects of different scanning techniques on the trueness (distance and angular deviations; P < .001) and scan time (P = .002) were statistically significant. For precision, different scanning techniques had only a significant effect on the distance deviation (P < .001). CONCLUSION: Regarding trueness and precision, none of the scanning techniques was superior to others. The scan body splinting technique led to significantly less scan time.

Implant-supported overdenture in an elderly patient with Huntington's disease.

Huntington's disease is a hereditary, progressive, neuro-degenerative disorder characterised by increasingly severe motor impairment, cognitive decline and behavioural manifestations leading to functional disability. Dyskinesia and hyperkinesia of the tongue and the peri-oral musculature make it impossible for the patient to wear a conventional complete denture, despite an adequate alveolar ridge. The present paper reports on a patient with Huntington's disease who was rehabilitated with a mandibular overdenture supported by two endosteal implants. One year follow-up examination showed that the prosthesis was stable and there was considerable improvement in the patient's masticatory function.

Accuracy of single implant scans with a combined healing abutment-scan body system and different intraoral scanners: An in vitro study.

OBJECTIVE: The aim of the present study was to evaluate the accuracy of single implant scans with a combined healing abutment-scan body (CHA-SB) system using different intraoral scanners. METHODS: A partially edentulous model with an implant was fabricated, and a CHA-SB system was secured on the implant. The model was scanned using an industrial-grade blue light scanner (ATOS Core 80) and a master reference model was generated (MRM). The model was also scanned with 4 different intraoral scanners (IOSs) [(Virtuo Vivo (VV), TRIOS 3 (T3), Omnicam (CO), and Primescan (PS)]. Test scans (n = 8) were superimposed over the MRM using the best fit algorithm (GOM Inspect 2018; GOM GmbH). After superimpositions, distance and angular deviations at selected areas on CHA-SB system were calculated. The data were analyzed with a 1-way ANOVA and Tukey HSD tests for trueness and precision (α=0.05). RESULTS: The differences in trueness (distance deviations) among tested IOSs were nonsignificant (P=.652). VV presented the highest angular deviations (P ≤.031), and the angular deviations in other IOS scans were not found different (P ≥.378). The precision of distance deviation data was not significantly different among scanners (P=.052). For the precision of angular deviation data, significant differences were found among IOSs (P=.002). Compared with PS (P=.007) and T3 (P=.014), VV had significantly lower precision, which was not significantly different than that of CO (P=.815). CONCLUSIONS: The accuracy (angular deviation) of scans of a combined healing abutment-scan body system on a single implant varied depending on the IOS. VirtuoVivo scans had the lowest accuracy in terms of angular deviations. When the distance deviation data were considered, scan accuracy of scanners was similar. CLINICAL SIGNIFICANCE: A recently introduced combined healing abutment-scan body system combines the acquisition of both the implant and the soft tissue. When different intraoral scanners scan the combined healing abutment-scan body system, the scan accuracy may vary.

Effect of implant location and operator on the accuracy of implant scans using a combined healing abutment-scan body system.

OBJECTIVES: To investigate the effect of implant location and operator on the accuracy of implant scans conducted with a combined healing abutment-scan body (CHA-SB) system. MATERIAL AND METHODS: A CHA-SB system was fixed on implants at left central incisor, first premolar, and first molar sites in a dentate maxillary model. An industrial optical scanner (ATOS Core 80) was utilized to scan and generate a reference model (RM). The model was scanned by three operators (n = 8) using an intraoral scanner (TRIOS 3). A software (GOM Inspect) was used to superimpose IOS test scans over RM and calculations (distance and angular deviations) were carried out to evaluate the accuracy of the scans. Data were compared with a 2-way ANOVA and Tukey HSD tests were employed to resolve significant interactions for trueness and precision (α = .05). RESULTS: Implant location affected the trueness (P ≤ .001) and the precision (P ≤ .020) (distance and angular deviations). The scans of the implant at the central incisor site had the highest trueness (distance and angular deviations) (P ≤ .016). The scans of the implant at molar site had the lowest precision (distance deviation data) (P ≤ .012). The scans of the implant at premolar site had lower precision (angular deviation data) than the scans of the implant at central incisor site (P = .016). Operators' effect on the accuracy of scans was not significant (P ≥  .051). CONCLUSION: Implant location affected the scan accuracy of the combined healing abutment-scan body system. The scans of the implant at central incisor site had high trueness. The posterior the implant location, the lower was the precision of the scans. The accuracy of scans of different operators was similar. CLINICAL SIGNIFICANCE: Higher deviations found in scans of posterior maxilla compared with those in the anterior region may require increased chairside adjustments when crowns are to be fabricated using the scans of the tested healing abutment-scan body system. However, clinical studies are necessary to corroborate the findings.

Spontaneous early exposure and marginal bone loss around conventionally and early-placed submerged implants: a double-blind study.

PURPOSE: The aim of this retrospective study was to compare the frequency of spontaneous early exposure of cover screws and marginal bone resorption in conventionally and early-placed submerged implants before second-stage surgery. MATERIALS AND METHODS: A total of 103 Nobel Biocare Branemark implants were conventionally (Group 1), or early-placed (Group 2) in 46 consecutive patients following the two-stage surgical protocol. Patients in both groups received oral hygiene training in self-performed plaque control measures, including exposure of cover screws during healing. Spontaneous cover screw exposure (CSE) of each implant was recorded for both groups and scored from Class 0 (no perforation) to Class 4 (complete exposure). Plaque index scores were recorded and marginal bone-level (MBL) changes were measured in radiographs before second-stage surgery in a blind manner. RESULTS: MBL in Group 2 was higher than Group 1 in patients with or without interim prosthesis (P<0.05). The use of interim prosthesis did not increase MBL in Group 1, but led to higher MBL in Group 2. The percentage of non-exposed implants in Group 1 was higher than Group 2 (P=0.007, odds ratio=7). Group 1 implants had 11.5 times greater plaque index score 0 than those in Group 2 (P=0.031, odds ratio=11.5). The differences between MBL with regard to CSE scores 0 and 1-4 was significant for both sides in Group 2 and the mesial side in Group 1 (P<0.05). The difference between MBL with regard to plaque index scores 1-3 was similar in both groups (P>0.05). CONCLUSIONS: There is a direct relation between spontaneous early cover screw perforations with early crestal bone loss. Early-placed implants experienced more spontaneous perforations and associated bone loss in comparison with conventionally placed submerged implants. The use of interim dentures may lead to more CSE and consequent MBL in the early-placement protocol.

Systematic review of prosthetic maintenance requirements for implant-supported overdentures.

PURPOSE: To evaluate prosthetic maintenance requirements for implant-retained/supported overdentures via a review of the literature. MATERIALS AND METHODS: Using the combined search terms "implant and overdenture," "implant-supported overdenture," "implant-retained overdenture," and "implant-anchored overdenture," along with specific inclusion and exclusion criteria, eligible articles between 1997 and 2008 (up to April 1) were retrieved from PubMed, EMBASE, OVID, the Cochrane Library databases, and seven journals by hand-searching. The initial search yielded 3,120 titles, and 287 articles were assigned to full-text analysis. Upon classification of the prosthetic complications with regard to the jaws treated and the attachment systems used, within- and between-group comparative frequency analyses were undertaken with the Kruskal-Wallis test or the Mann-Whitney U test at P < .05. RESULTS: A total of 49 articles were included. Within- and between-group evaluations with regard to jaw treated as well as the attachment systems used showed that the frequency of complications did not change over time (P > .05). The differences detected were more matrix replacements after 5 years in the maxilla and mandible and more matrix replacements and patrix fractures after the first year in the mandible (P < .05). Among the attachment systems, a dislodged, worn, or loose matrix or its respective housing was more common in the ball-attachment group after the first year (P < .05). Prosthetic complications for all types of attachments were comparable (P > .05), except for the differences in peri-implant or interabutment mucosal enlargement rates after 1 year. CONCLUSIONS: Prosthetic maintenance requirements for overdentures on both jaws seem to be comparable. The impact of attachment system on the prosthetic outcome is negligible.

A systematic review of marginal bone loss around implants retaining or supporting overdentures.

PURPOSE: To evaluate, through a systematic review of the literature, the effects of implant design and attachment type on marginal bone loss in implant-retained/supported overdentures. MATERIALS AND METHODS: With the combined search terms "implant and overdenture," "implant-supported overdenture," "implant-retained overdenture," and "implant-anchored overdenture," along with specific inclusion and exclusion criteria, eligible articles between 1997 and 2008 (up to April 1) were retrieved from PubMed, EMBASE, OVID, the Cochrane Library databases, and seven journals by hand searching. Marginal bone loss values with regard to time, attachment type, and implant system used were compared by Kruskal-Wallis tests. Means and standard deviations of data were combined using fixed- and random-effect models and evaluated using meta-analysis. RESULTS: Forty-six articles were included in the analyses; data extraction and meta-analysis were able to be conducted on eight studies. Data regarding maxillary overdentures could not be analyzed statistically. Bone loss around mandibular implants did not seem to be influenced by implant system or attachment design (bar, ball, magnet, and other types) in the first year, from 1 to = or < 5 years, and even after 5 years (P > .05). Meta-analysis could not detect differences in implant systems or attachment types (P > .05). CONCLUSIONS: Based upon a systematic review and meta-analysis of the literature that identified a total of 4,200 implants from 13 manufacturers, there was no difference in marginal bone loss around implants retaining/supporting mandibular overdentures relative to implant type or attachment designs.

The effect of scanner type and scan body position on the accuracy of complete-arch digital implant scans.

BACKGROUND: How the accuracy of complete-arch implant scans is affected when different intraoral scanners (IOSs) are used and the effect of scan body position on the accuracy are not well-known. PURPOSE: To compare the scan accuracy (trueness and precision) of a recently introduced IOS (Virtuo Vivo) to a commonly used IOS (TRIOS 3) and the scans of a laboratory scanner (LBS; Cares 7 SERIES) in a completely edentulous maxilla with four implants. It was also aimed to evaluate the effect of scan body position on the accuracy. MATERIALS AND METHODS: Multi-unit scan bodies were tightened on a poly(methyl methacrylate) edentulous maxillary model with four implants. A master reference model (MRM) stereolithography (STL) file was generated by scanning the model with a high-precision scanner. The model was scanned with three different scanners (n = 10); two different IOSs and a LBS. STL files were superimposed over the MRM. RESULTS: For trueness, scan body position (P = .004) and scanner type (P < .001) had a significant effect on distance deviation and a significant interaction was found (P = .001). For angular deviation, only scanner type had a significant effect (P = .028). For precision, significant difference was found for distance (P = .011) and angular deviations (P = .020) between different scanner types. CONCLUSIONS: One scanner type was not superior to others when both trueness and precision were considered. Position of the scan body affected the distance deviation (trueness).

Fresh-frozen vs. embalmed bone: is it possible to use formalin-fixed human bone for biomechanical experiments on implants?

PURPOSE: As formalin is an extremely reactive electrophilic chemical that reacts with tissues, the purpose of this study was to explore whether formalin fixation could potentially alter the mechanical properties of bone tissue and have an effect on the primary stability measurements of implants. MATERIAL AND METHODS: Ø 3.3 x 8 mm, Ø 4.1 x 8 mm, and Ø 4.8 x 8 mm implants were placed on sockets prepared into the anterior surface of the radius of two fresh-frozen human cadavers. The insertion torque of each implant was quantified using a strain-gauged torque-wrench connected to a data acquisition system at a sample rate of 10 KHz, and resonance frequency analysis measurements were also undertaken for each implant. The cadavers were then subjected to embalment with 10% formalin for 3 months, and the same experiments were undertaken on the contra lateral radius of the cadavers. RESULTS: The insertion torques before and after chemical fixation were similar for Ø 3.3 mm (P>0.05), and higher values were obtained for Ø 4.1 mm and Ø 4.8 mm implants after chemical fixation (P<0.05). The resonance frequency analysis values before and after chemical fixation were similar for all implants (P>0.05). CONCLUSIONS: Implants have higher insertion torque values in formalin-fixed bone than fresh-frozen human bone, but similar implant stability quotients in both cases. The insertion torque technique can detect the difference between formalin-fixed and fresh-frozen human bone, but resonance frequency analysis cannot.

Implant stability and bone density: assessment of correlation in fresh cadavers using conventional and osteotome implant sockets.

OBJECTIVE: To compare the primary stability of implants placed in conventional and osteotome sites and to evaluate the level of correlation between cutting torque measurements, resonance frequency analysis (RFA), and bone density. MATERIALS AND METHODS: Eight human femoral heads were scanned with computed tomography for bone density measurements as Hounsfield units (HU), and individualized computed tomography-based surgical stents were prepared for placement of implants. Five implant sockets were prepared in each collum (CoF), caput (CaF), and trochanter (Tr-MM) section of the femoral heads using the conventional drilling technique or by a combination of drilling and use of an osteotome. Cutting-torque values (CTV) of the implants were measured by a manual torque wrench, followed by determination of implant stability quotients (ISQ) by RFA. RESULTS: The CTVs of implants were similar in the conventional group, but different in the osteotome group (P<0.05). There was a general tendency toward achieving higher CTV and ISQ values in CoF than CaF and Tr-MM (P<0.05), and measurements in CaF and Tr-MM were comparable (P>0.05). The mean HU of sites were similar, although CoF had higher HU values (P>0.05). CTV of implants in CaF and Tr-MM and ISQ values in CoF in the conventional groups were higher than those in the osteotome groups (P<0.05). The correlation between CTV and HU in Tr-MM was significant in the osteotome group, although no other correlations between CTV, ISQ, and HU could be detected (P>0.025). CONCLUSIONS: Conventional placement led to higher implant stability than the drilling and osteotome technique used in the study. No correlation could be found between CTV, RFA, and bone density.

Human ex vivo bone tissue strains around immediately-loaded implants supporting mandibular fixed prostheses.

PURPOSE: The purpose of this study was to qualify and quantify bone strains around immediately-loaded implants supporting mandibular fixed prostheses with regard to number of implant support. MATERIALS: Linear strain gauges were bonded on the labial bone of 5 Straumann dental implants placed in the mandibular symphysis region of 2 completely edentulous mandibles of fresh human cadavers. Installation torque value of each implant was measured by a custom-made torque wrench and resonance frequency analyses were undertaken. A one-piece full-arch fixed prosthesis was fabricated for each cadaver and 2 miniature load cells were integrated in the cantilever region of the prostheses for controlled loading experiments. 5-, 4-, and 3-implant support designs were consecutively tested. Strain measurements were performed at a sample rate of 10 KHz and under a maximum load of 100 N, simultaneously monitored from a computer connected to data acquisition system. RESULTS: The installation torque values and implant stability quotient values of the implants ranged between 42.12 to 145.67 N cm and 61 to 80, respectively. Between-group comparisons revealed that the highest strain magnitudes were recorded for the 3-implant design followed by the 4- and 5-implant designs, although there was a tendency toward similar load partitioning between 4- and 5-implant designs (P < 0.05). CONCLUSIONS: Bone strains around 3-implant supported mandibular fixed prostheses is significantly higher than those around 4- and 5-implant designs, and this may lead to failure of supporting implants. Four- and 5-implant designs might have similar clinical outcome.

A randomized controlled clinical trial of feldspathic versus glass-infiltrated alumina all-ceramic crowns: a 3-year follow-up.

PURPOSE: The aim of this randomized controlled clinical trial was to compare the outcome of feldspathic porcelain (group 1) and glass-infiltrated alumina all-ceramic (group 2) crowns. MATERIALS AND METHODS: Patients were recruited based on inclusion/exclusion criteria, and 33 eligible subjects were assigned randomly to one of the two treatment groups. One hundred one crowns were placed predominantly in the anterior portion of the mouth and were cemented using resin cement. A baseline California Dental Association quality evaluation was completed, and Plaque and Gingival Index scores were recorded. Prosthetic and soft tissue scores were recorded for up to 3 years. RESULTS: Five restorations experienced mechanical failure. Kaplan-Meier analysis showed that the 3-year survival probabilities for group 1 (0.94) and group 2 (0.95) restorations were comparable (P = .484). Plaque and Gingival Index scores for both groups were similar at the 3-year recall (P > .999). Marginal integrity, anatomical form, and color and surface scores were also similar for both groups (P > .05). CONCLUSION: Feldspathic and glass-infiltrated alumina all-ceramic crowns placed predominantly in the anterior portion have comparable biologic and prosthetic outcomes, as well as survival probabilities.

CAD/CAM Zirconia vs. slip-cast glass-infiltrated Alumina/Zirconia all-ceramic crowns: 2-year results of a randomized controlled clinical trial.

The aim of this randomized controlled clinical trial was to compare the early clinical outcome of slip-cast glass-infiltrated Alumina/Zirconia and CAD/CAM Zirconia all-ceramic crowns. A total of 30 InCeram Zirconia and Cercon Zirconia crowns were fabricated and cemented with a glass ionomer cement in 20 patients. At baseline, 6-month, 1-year, and 2-year recall appointments, Californian Dental Association (CDA) quality evaluation system was used to evaluate the prosthetic replacements, and plaque and gingival index scores were used to explore the periodontal outcome of the treatments. No clinical sign of marginal discoloration, persistent pain and secondary caries was detected in any of the restorations. All InCeram Zirconia crowns survived during the 2-year period, although one nonvital tooth experienced root fracture coupled with the fracture of the veneering porcelain of the restoration. One Cercon Zirconia restoration fractured and was replaced. According to the CDA criteria, marginal integrity was rated excellent for InCeram Zirconia (73%) and Cercon Zirconia (80%) restorations, respectively. Slight color mismatch rate was higher for InCeram Zirconia restorations (66%) than Cercon Zirconia (26%) restorations. Plaque and gingival index scores were mostly zero and almost constant over time. Time-dependent changes in plaque and gingival index scores within and between groups were statistically similar (p>0.05). This clinical study demonstrates that single-tooth InCeram Zirconia and Cercon Zirconia crowns have comparable early clinical outcome, both seem as acceptable treatment modalities, and most importantly, all-ceramic alumina crowns strengthened by 25% zirconia can sufficiently withstand functional load in the posterior zone.

Effects of prosthesis design and impression techniques on human cortical bone strain around oral implants under load.

PURPOSE: The purpose of this study was to evaluate the effects of two different prosthetic designs (screw-retained versus cement-retained) and two impression techniques (open versus closed tray) on bone-level strains around implants. MATERIALS AND METHODS: Two Ø 4.1 mm x 10 mm Straumann implants were placed in the bilateral fibulas of six fresh cadavers; bone segments were removed en bloc. Twelve implant-level and six abutment-level (18 total) working casts were made to fabricate fixed partial dentures, resulting in three test groups: Group 1: closed-tray technique/implant-level model/screw-retained prostheses; Group 2: closed-tray technique/abutment-level model/cement-retained prostheses; Group 3: open-tray technique/implant-level model/screw-retained prostheses. Linear strain-gauges were bonded to the cortical bone between implants and the lateral wall of the fibula in close proximity to the implant necks in each bone fragment. Strain-gauge signals were digitized by a data acquisition system and corresponding software at a sample rate of 10 KHz, simultaneously monitored from the computer during application of an external static load of 150 N on the middle of the pontic, using a loading frame. RESULTS: The approximal and lateral strains were extremely similar in both prosthetic groups (p>0.05). Within-group comparisons for the indirect impression technique showed that approximal and lateral strains in screw- and cement-retained prostheses were similar (p>0.05). Neither the prostheses design nor the impression technique had any discernable effect on bone-level strain. CONCLUSION: Strains on the cortical bone around two implant supported, 3-unit screw- or cement-retained fixed prostheses, fabricated either by direct or indirect impression techniques on Straumann dental implants, are similar under a 150 N static load.

Multidisciplinary approach for the treatment of an oblique root fracture: a case report.

This clinical case study describes a multidisciplinary modified technique for the treatment of an oblique root fracture. A-38-year old woman with a history of trauma and a broken tooth was referred to our clinic. There was an oblique crown fracture extending the coronal third of the root just underneath the cingulum of the crown. The patient was willing to keep her tooth in function by any means. Two weeks after root canal therapy the flap was raised. The coronal two third of the root canal was enlarged. An impression of the enlarged root canal and tooth surface with surrounding bone was taken. The flap was sutured and the impression was sent to the laboratory for the post-casting preparation. After 7 days, the flap was opened again and casting was cemented. The flap was sutured. Ten days after the second surgery, three anterior teeth were prepared and a final impression was taken for the preparation of porcelain crowns. Restoration was finished 15 days after the second operation. The patient is still under maintenance therapy and the 12 month results are presented in this report. Extraction may not be the only alternative for the root fractures. Even for fractures under the alveolar margin, alternative multidisciplinary approaches can be used to restore and allow the tooth to survive.

Fabrication of a screw-retained fixed provisional prosthesis supported by dental implants.

Screw-retained provisional implant-supported prostheses may have advantages over cement-retained prostheses in certain situations. This article describes a technique for fabrication of screw-retained provisional acrylic resin implant-supported prostheses from the modified metal components provided with the implant.

CAD/CAM Zirconia vs. slip-cast glass-infiltrated Alumina/Zirconia all-ceramic crowns: 2-year results of a randomized controlled clinical trial

The aim of this randomized controlled clinical trial was to compare the early clinical outcome of slip-cast glass-infiltrated Alumina/Zirconia and CAD/CAM Zirconia all-ceramic crowns. A total of 30 InCeram® Zirconia and Cercon® Zirconia crowns were fabricated and cemented with a glass ionomer cement in 20 patients. At baseline, 6-month, 1-year, and 2-year recall appointments, Californian Dental Association (CDA) quality evaluation system was used to evaluate the prosthetic replacements, and plaque and gingival index scores were used to explore the periodontal outcome of the treatments. No clinical sign of marginal discoloration, persistent pain and secondary caries was detected in any of the restorations. All InCeram® Zirconia crowns survived during the 2-year period, although one nonvital tooth experienced root fracture coupled with the fracture of the veneering porcelain of the restoration. One Cercon® Zirconia restoration fractured and was replaced. According to the CDA criteria, marginal integrity was rated excellent for InCeram® Zirconia (73 percent) and Cercon® Zirconia (80 percent) restorations, respectively. Slight color mismatch rate was higher for InCeram® Zirconia restorations (66 percent) than Cercon® Zirconia (26 percent) restorations. Plaque and gingival index scores were mostly zero and almost constant over time. Time-dependent changes in plaque and gingival index scores within and between groups were statistically similar (p>0.05). This clinical study demonstrates that single-tooth InCeram® Zirconia and Cercon® Zirconia crowns have comparable early clinical outcome, both seem as acceptable treatment modalities, and most importantly, all-ceramic alumina crowns strengthened by 25 percent zirconia can sufficiently withstand functional load in the posterior zone.