Digital workflow for prosthetic management of malpositioned implant in an adolescent patient: A 20-year follow-up.

OBJECTIVE: Dental implants placed in adolescent patients pose a challenge to restore and maintain an esthetic outcome over longer period of follow-up. Maxillomandibular changes throughout adulthood may lead to complications such as implant infraocclusion and interproximal contact loss. This case report describes an alternate prosthetic treatment strategy for maxillary single implant placed in an adolescent patient in the esthetic zone with inappropriate implant axis and screw hole placement. CLINICAL CONSIDERATIONS: With temporary restorations, the gingiva and soft tissues were shaped to imitate the emerging profile of the contralateral side. A zirconia screw-retained abutment was customized as a copy-mirror from the contralateral prepared tooth to mimic the exact shape and to avoid labiolingual over contour by computer-aided design/computer-assisted manufacture (CAD/CAM). The porcelain laminate veneer was bonded to the zirconia abutment. Porcelain adhesive approach was used instead of traditional principles of retention and resistance form of the abutment. CONCLUSIONS: A functional and esthetic outcome was achieved and maintained, while a minimally invasive procedure was implemented to use the malplaced implant instead of explanting it. CLINICAL SIGNIFICANCE: The present report illustrates the prosthetic management of a malpositioned dental implant placed 20 years ago, utilizing a minimally invasive digital protocol.

Treatment planning algorithm for patients with a terminal dentition.

This article discusses the variables that affect the diagnostic process in patients with a compromised dentition and addresses the clinical decision of whether to extract or maintain teeth. A decision tree algorithm is proposed to guide clinicians in planning complete arch rehabilitations.

Effect of dental implant therapy on the preservation of orofacial tissues: A systematic review and meta-analysis.

OBJECTIVE: Fundamentally, this review addresses the following question: In partially or fully edentulous patients, do implant-supported dental prostheses preserve orofacial tissues when compared to conventional prostheses or no therapy? MATERIALS AND METHODS: This study was conducted according to the 2020 PRISMA guidelines for systematic reviews. Electronic searches were conducted at PubMed and Embase databases followed by manual search. Clinical studies comparing the effect of implant-supported prostheses with conventional rehabilitation or no treatment on alveolar bone resorption, remaining teeth, and jaw muscle thickness were considered for inclusion. A qualitative synthesis was conducted with all included studies, and data from selected studies were pooled quantitatively to perform a meta-analysis. RESULTS: A total of 14 studies were selected for analysis. Six studies reported on the effect of implant therapy on alveolar bone resorption (n = 453), six on the remaining teeth (n = 1014), while four studies evaluated masseter muscle thickness (n = 158). The results of the meta-analyses assessing alveolar bone resorption in the posterior mandible and in the anterior area of the maxilla, both fixed and random effects models, yielded no benefit of rehabilitation with implant-supported prostheses when compared to conventional prostheses. For masseter bone thickness, however, a significant benefit for implant-supported prosthesis was observed. CONCLUSIONS: This systematic review and meta-analysis were unable to unequivocally answer the focus question. There are some indicators of the benefit of implant-supported prostheses over conventional prostheses or no therapy in preserving orofacial tissues, particularly for masseter muscle thickness. However, the evidence is still insufficient to confirm such perception.

Group 4 ITI Consensus Report: Patient benefits following implant treatment in partially and fully edentulous patients.

OBJECTIVES: The aim of Working Group 4 was to address patient benefits associated with implant dentistry. Focused questions on (a) dental patient-reported outcomes (dPROs), (b) improvement in orofacial function, and (c) preservation of orofacial tissues in partially and fully edentulous patients following provision of implant-retained/supported dental prostheses were addressed. MATERIALS AND METHODS: Three systematic reviews formed the basis for discussion. Participants developed statements and recommendations determined by group consensus based on the findings of the systematic reviews. These were then presented and accepted following further discussion and modifications as required by the plenary of the 7th ITI Consensus Conference, taking place in 2023 in Lisbon, Portugal. RESULTS: Edentulous patients wearing complete dentures (CD) experience substantial improvements in overall dPROs and orofacial function following treatment with either complete implant-supported fixed dental prostheses (CIFDP) or implant overdentures (IODs). With respect to dPROs, mandibular IODs retained by two implants are superior to IODs retained by one implant. However, increasing the number of implants beyond two, does not further improve dPROs. In fully edentulous patients, rehabilitation with CIFDP or IOD is recommended to benefit the preservation of alveolar bone and masseter muscle thickness. CONCLUSIONS: Completely edentulous patients benefit substantially when at least the mandible is restored using an CIFDP or an IOD compared to CD. In fully edentulous patients, implant prostheses are the best option for tooth replacement. The availability of this treatment modality should be actively promoted in all edentulous communities, including those with limited access and means.

Clinician preferences for single-unit implant restoration designs and materials: A survey of the membership of the Pacific Coast Society for Prosthodontics.

STATEMENT OF PROBLEM: Clinical research has difficulty keeping pace with the rapid evolution of materials, protocols, and designs of single-unit implant restorations. The clinical design preferences of prosthodontics for different clinical scenarios are lacking. PURPOSE: The purpose of this cross-sectional survey was to determine the current prevalence of usage of various treatment options and materials for single-unit implant-supported restorations. MATERIAL AND METHODS: From August to September of 2022, a survey invitation was sent to members of the Pacific Coast Society for Prosthodontics (PCSP). The survey was hosted online and asked 37 questions related to the materials, protocols, and design preferences for single-unit implant-supported restorations in various clinical scenarios. The prompts included the suggestion that answers should be based on preferences for the "ideal" treatment of a hypothetical patient seeking implant treatment for the replacement of a single missing tooth. RESULTS: Of 133 questionnaires sent via email, 35 were returned. The results are presented with histograms that use color coding as an experience proxy metric. A total of 87% of respondents was in private practice, and 60% reported having restored more than 1000 single-unit implant restorations. For the replacement of a single maxillary central incisor under ideal conditions and angulation through the palatal surface, respondents preferred bone level implants (93%) and screw-retained restorations (80%), with 50% of those being zirconia with a titanium abutment and 21% being cast metal-ceramic. For an identical scenario, except that the angulation would be through the facial surface, respondents preferred the angled screw system (55%) and cemented (41%) restorations. For the replacement of a single missing mandibular molar under ideal conditions, respondents preferred bone level implants (79%) and screw-retained restorations (79%), with 70% of those being zirconia with a titanium abutment and 17% being cast metal-ceramic. CONCLUSIONS: While a wide range of protocols, designs, and materials exist for the replacement of a single missing tooth, these results provide a snapshot of current single-unit implant prosthodontic preferences in the Western United States and Canada.

Effect of supramucosal height of a scan body and implant angulation on the accuracy of intraoral scanning: An in vitro study.

STATEMENT OF PROBLEM: Intraoral scanners (IOSs) provide a digital alternative to conventional implant impression techniques. However, the effect of the supramucosal height of the scan body and implant angulation on the accuracy of IOSs remains unclear. PURPOSE: The purpose of this in vitro study was to measure the impact of the supramucosal height of the scan body and implant angulation on the accuracy (trueness and precision) of intraoral digital implant scans in partially edentulous models. MATERIAL AND METHODS: Two maxillary partially edentulous casts with 4 implant analogs were fabricated, 1 with 4 parallel implants (P-groups) and 1 with 2 implants distally inclined 18 degrees (A-groups). An implant scan body was positioned on each implant analog (CARES RC Mono Scanbody). For each cast, 3 subgroups were determined based on the soft tissue moulage fabricated for each reference cast exposing 3 mm (P-3 and A-3 subgroups), 5 mm (P-5 and A-5 subgroups), and 7 mm (P-7 and A-7 subgroups) of the implant scan bodies. The 2 reference casts were registered by using a coordinate measurement machine and desktop scanner (7 Series Dental Wings) and then scanned using an IOS (TRIOS 4) (n=15). Linear and angular discrepancy values and root mean square (RMS) error values between the implant scan bodies measured on the reference and experimental scans were computed with an inspection software program (Geomagic). Mann-Whitney U tests with Bonferroni correction were applied for planned comparisons (α=.05/9 ≈ .006). RESULTS: For linear discrepancies, statistically significant differences were found between groups P-3 and A-3 (P=.004) and between P-7 and A-7 (P=.005). For angular discrepancies, statistically significant differences were found between groups A-3 and A-5 (P=.002) and between P-7 and A-7 (P=.003). The RMS error analysis found no statistically significant differences among the groups. CONCLUSIONS: Implant angulation of 18 degrees did not significantly affect the accuracy of the intraoral scans in terms of 6 of the 9 planned comparisons, although the angled groups had lower mean values. Also, the supramucosal height of the scan body did not significantly affect the accuracy of the intraoral scans in terms of 17 of the 18 planned comparisons. Results may vary with different implant scan body designs.

Accuracy of static computer-aided implant surgery (S-CAIS) using CAD-CAM surgical templates fabricated from different additive manufacturing technologies.

STATEMENT OF PROBLEM: Different 3D printers are available for guided implant surgery, but studies that evaluate their source of errors and their cost-effectiveness are lacking. PURPOSE: The purpose of this in vitro study was to compare the accuracy of different 3-dimensional (3D) printed surgical templates made using different additive manufacturing technologies and to evaluate the effect of implant location on the accuracy of fully guided implant placement. MATERIAL AND METHODS: Fifty partially edentulous maxillary typodonts with edentulous sites in the right second premolar (SP), right lateral incisor (LI), left central incisor (CI), and left first molar (FM) locations were scanned and printed from the standard tessellation language (STL) datasets. The study compared 5 groups for the fabrication of implant surgical templates: Varseo S-Bego (Bego), Polyjet-Stratasys (Poly), Low Force Stereolithography-FormLabs (LFS), P30+-Straumann (P30), and M2-Carbon (M2). After fully guided implant placement, the typodont was scanned, and the 3D implant positions were compared with the master model by superimposing the STL files. Descriptive statistics were calculated for groups and subgroups, and comparisons among the groups and subgroups were conducted via 2-way mixed analysis of variance, Tukey honest significant difference, and post hoc Bonferroni tests (α=.05). RESULTS: The results were site specific and not consistent within each group. For angle deviation, the within-group analysis for P30 demonstrated significantly lower values for implants positioned at site SP (1.4 ±0.8 degrees) than for sites LI (2.3 ±0.7 degrees; P=.001) and CI (2.3 ±0.8 degrees; P=.007). For 3D offset at base for implant CI, LFS was significantly higher than Bego (P=.002), Poly (P=.035), or M2 (P=.001); P30 was also significantly higher than Bego (P=.014) and M2 (P=.006). LFS had a significantly higher 3D offset at the tip than Bego (P=.001) and M2 (P=.022) for implant CI. CONCLUSIONS: The choice of 3D printer seemed to influence fully guided implant surgery in terms of the final implant position compared with initial implant planning. However, although statistically significant differences were present across groups, all additive manufacturing technologies were within clinically acceptable values.

Complete Digital Workflow for Prosthesis Prototype Fabrication with Double Digital Scanning: Accuracy of Fit Assessment.

PURPOSE: To assess the accuracy of a complete digital workflow protocol for fabrication of printed prosthesis prototypes for maxillary immediate loading treatment. MATERIALS AND METHODS: A maxillary stone cast with 4 abutment-level implant analogs with adequate antero-posterior spread was fabricated. This stone cast served as a reference cast and a zirconia prosthesis was also fabricated to serve as an interim prosthesis. Double digital scanning was used for digital scans of the reference cast and the interim prosthesis, respectively. An intraoral scanner (TRIOS® 3) was used to capture the standard tessellation language (STL) files. These STL files were then imported to computer-aided design (CAD) software (Exocad DentalCAD) and superimposed into a final design STL file that was exported to 3 different (Form 3b+, Carbon M2, Sprintray Pro95) three-dimensional (3D) printers to produce a total of 90 printed prototypes (n = 30 from each 3D printer). Two blinded clinicians assessed the accuracy of fit of each digitally fabricated prosthesis prototype on the reference cast, utilizing the screw-resistance test and radiographs. The Fisher's exact test was used to test the difference between the groups. RESULTS: Out of the 90 digitally fabricated prototypes, 86 (95.6%) presented with accurate fit. The accuracy of fit ranged from 87% (26/30) for Sprintray Pro95 to 100% (30/30) for the Form 3b+ and M2 Carbon groups. CONCLUSIONS: Digitally fabricated prosthesis prototypes can be generated with a complete digital workflow leading to clinically acceptable fit, while reducing the number of appointments and treatment time. The 3D printer had an effect on the accuracy of prosthesis prototype fit.

Reverse scan body: A complete digital workflow for prosthesis prototype fabrication.

PURPOSE: To assess the accuracy of fit of prosthesis prototypes fabricated via a complete digital workflow protocol with a reverse scan body skipping intraoral scanning for implant data acquisition. MATERIALS AND METHODS: A maxillary stone cast with four multiunit abutment implant analogs (Screw-Retained Abutments, Institut Straumann AG, Basel, Switzerland) with adequate anteroposterior spread simulated a common clinical patient situation. This stone cast served as the master cast and an interim screw-retained prosthesis was fabricated on it. Novel reverse scan bodies were connected to the interim prosthesis, and extraoral scanning was performed with a white light intraoral scanner. The produced standard tessellation language (STL) files were then imported to computer-assisted design software and after the digital design, the STL file was exported to a computer-assisted machining milling machine and a three-dimensional (3D) printer to produce a total of 50 milled and 50 printed fixed complete denture prototypes, respectively. Two clinicians assessed the accuracy of fit of each digitally fabricated prosthesis prototype on the master cast, utilizing the screw-resistance test and radiographic evaluation. Out of the 100 prototypes, 94% (94/100) were fitting accurately. Fisher's exact test was used to test the difference among the groups. The test revealed statistically significant results (p = 0.027). RESULTS: Out of the 50 digitally fabricated milled prosthesis prototypes, 50 (100%) presented with accurate fit under in vitro assessment. Out of the 50 digitally fabricated 3D printed prototypes, 44 (88%) presented with accurate fit under in vitro assessment. CONCLUSIONS: Accurately fitting digitally fabricated prosthesis prototypes can be milled after extraoral scanning with reverse scan bodies without intraoral implant data acquisition.

Reverse scan body: The scan pattern affects the fit of complete-arch prototype prostheses.

PURPOSE: To assess the effect of different scan patterns on the fit of implant-supported complete-arch prototype prostheses fabricated via a complete digital extraoral protocol with a reverse scan body. MATERIALS AND METHODS: A mandibular cast with four multi-unit abutment (MUA) implant analogs with adequate antero-posterior spread served as the reference cast, simulating a common clinical patient situation, and a polymethylmethacrylate interim screw-retained prosthesis was fabricated on it. Novel reverse scan bodies were connected to the interim prosthesis on the intaglio of the MUA abutments and extraoral scanning was performed with a white light intraoral scanner (TRIOS 4; 3 shape) and three different scan patterns: starting from the occlusal surface of the interim prosthesis (O-group), starting from the intaglio (I-group), and helix pattern (H-group).  The resulting STL files from the three groups were then imported to computer-aided design (CAD) software and after the digital design, the STL files were exported to a computer-aided manufacturing (CAM) milling machine which generated a total of 15 CAD-CAM milled prototype prostheses per group. Two clinicians assessed the fit of each digitally fabricated prototype prosthesis on the reference cast, utilizing the screw-resistance test and radiographic evaluation. Fisher's exact test was used to test the difference between the three groups, and Cohen's k-score was used to assess the inter-examiner agreement. RESULTS: Out of the three different groups, the O-group scan pattern led to 100% prosthesis fit, while the prototype prostheses generated from I- and H-groups had 80% and 53% fit, respectively. The results were statistically significant (p = 0.008). CONCLUSIONS: Occlusal scan pattern leads to fitting milled prototype prostheses after extraoral scanning with reverse scan bodies without intraoral implant data acquisition.

Complete digital workflow for prosthesis prototype fabrication with double digital scanning: A retrospective study with 45 edentulous jaws.

PURPOSE: To assess the accuracy of fit of complete-arch printed prosthesis prototypes generated with a digital workflow protocol for completely edentulous jaws. MATERIALS AND METHODS: Forty-five edentulous jaws (35 patients) underwent intraoral complete-arch digital scans with the double digital scanning (DDS) technique and the generated standard tessellation language (STL) files were superimposed and imported into computer-aided design software. After STL merging, each master STL file was used for printing a prosthesis prototype. The primary outcome was the accuracy of fit assessment of the printed prototypes on verified master stone casts. Two experienced clinicians tested the accuracy of fit with radiographs and screw-resistance tests. Secondary outcomes were the effect of the scan body shape and implant number on the accuracy of fit. RESULTS: Out of the 45 DDS-generated prosthesis prototypes, 39 presented with accurate fit on verified master stone casts, yielding an 86.70% accuracy of fit. Cylindrical scan bodies led to 100% accuracy of fit (25/25), whereas polygonal scan bodies presented with 70% accuracy of fit (14/20). Four implant-supported prostheses yielded 100% accuracy of fit (12/12), compared with 25/29 (86.30%) accuracy of fit for the six-implant-supported ones. Fisher's exact test was used to assess the effect of different scan body shapes (p = 0.005) and implant number on accuracy of fit. Chi-squared test was used to assess the association between the number of implants per arch and the accuracy of fit (p = 0.039). CONCLUSIONS: Thirty-nine out of 45 complete-arch prosthesis prototypes generated with a completely digital workflow presented with clinically acceptable fit. The effect of the scan body design and implant number was statistically significant, favoring cylindrical scan bodies and four-implant-supported prostheses.

Digital vs Conventional Full-Arch Implant Impressions: A Retrospective Analysis of 36 Edentulous Jaws.

PURPOSE: There is a paucity of comparative clinical studies assessing the accuracy of full-arch digital scans versus conventional implant impressions. The aim of this retrospective study was to compare the three-dimensional (3D) deviations between full-arch digital scans and conventional implant impressions for edentulous maxillae and mandibles. MATERIALS AND METHODS: Twenty-seven patients (36 edentulous jaws) were treated with one-piece, screw-retained implant-supported fixed complete dental prostheses (IFCDPs). Twenty-one jaws were maxillary, and 15 were mandibular. Full-arch conventional impressions and intraoral digital scans with scan bodies and an intraoral scanner had been taken during the impression phase. Following verification of the conventional stone casts, the casts were digitized. The generated standard tessellation language (STL) files from both impression techniques were merged and analyzed with reverse engineering software. The primary aim was to evaluate the accuracy between conventional and digital full-arch scans, while the effect of the edentulous jaw in 3D accuracy was the secondary aim. RESULTS: The cumulative 3D (mean ± SD) deviations between virtual casts from intraoral full-arch digital scans and digitized stone casts generated from conventional implant impressions were found to be 88 ±24 µm. In the maxillary group, the mean ± SD 3D deviation was 85 ±25 µm, compared to 92 ±23 µm for the mandibular group (p = 0.444). CONCLUSION: The 3D implant deviations found between the full-arch digital and conventional impressions lie within the clinically acceptable threshold. No statistically significant difference was identified between maxillary and mandibular jaws in terms of 3D deviations.

Survival rates, patient satisfaction, and prosthetic complications of implant fixed complete dental prostheses: a 12-month prospective study.

PURPOSE: To determine the survival rate, incidence of prosthetic complications, and patient satisfaction of implant fixed complete dental prostheses (IFCDPs) after a mean observation period of 1.4 years. MATERIALS AND METHODS: Twenty-eight (28) eligible participants were recruited according to specific inclusion and exclusion criteria. The definitive metal-acrylic resin IFCDPs consisted of titanium bars veneered with acrylic resin and acrylic denture teeth. Prosthodontic complications, divided into major and minor, were monitored. Parameters such as gender, jaw location, bruxism, and occlusal scheme were evaluated. Moreover, a questionnaire was administered throughout the study to assess patient satisfaction. Poisson regression as well as repeated measures ANOVA were used for statistical analysis. RESULTS: Fourteen (14) males and 14 females were enrolled and followed-up at 3, 6, and 12 months. All IFCDPs survived (100% survival rate). The most frequent minor complication was the loss of material used to close the screw access hole (20% out of total complications). The most frequent major complication was chipping of the acrylic denture teeth (77.14% out of total complications). Gender (p = 0.008) and bruxism (p = 0.030) were significant predictors for the total major complications (major wear and major chipping) while occlusal scheme was a significant predictor for major chipping events (p = 0.030). CONCLUSIONS: While IFCDPs demonstrated high prosthetic survival rates, they also exhibited a high number of chipping events of the acrylic veneering material, especially in males, bruxers, and individuals with canine guidance occlusion. However, the occurrence of these prosthetic complications did not negatively affect patient satisfaction.

A comparative retrospective study of different surgical guide designs for static computer-assisted implant surgery in posterior single edentulous sites.

AIM: The aim of this retrospective clinical study was to compare the accuracy of static Computer-assisted implant surgery (sCAIS) in posterior single edentulous patients using different surgical guide designs. MATERIALS AND METHODS: Thirty-seven partially edentulous patients with a total of 54 implants were included in the study. Seventeen implants were included in Group 1-Unbounded Tooth-Mucosa Supported; 18 implants in Group 2-Unbounded Tooth Supported; and 19 implants in Group 3 (Control)-Bounded Tooth Supported. All partially edentulous patients were treated with fully guided implant surgery using the corresponding surgical guide. Discrepancies between the pre-planned and post-operative implant position were evaluated. RESULTS: The mean angular deviation ± standard deviation (SD) was 2.91 ± 1.56°, 3.33 ± 1.72° and 2.25 ± 1.13° for Groups 1, 2, and 3, respectively. The mean ± SD 3D offset at base was 0.66 ± 0.29 mm, 0.77 ± 0.24 mm, and 0.49 ± 0.22 mm; and 3D offset at tip was 0.84 ± 0.45 mm, 1.07 ± 0.38 mm, and 0.75 ± 0.25 mm for Groups 1, 2, and 3, respectively. No statistically significant differences between groups were found for angular deviation. There were statistically significant differences between Groups 2 and 3 for 3D offset at base (p = .002) and 3D offset at tip (p = .010). CONCLUSIONS: Different surgical guide designs for posterior single edentulous areas appear to be associated with the accuracy level of sCAIS. In unbounded sites, having additional posterior attached soft tissue support is preferable.

Prosthesis accuracy of fit on 3D-printed casts versus stone casts: A comparative study in the anterior maxilla.

OBJECTIVE: To compare in vitro the accuracy of fit of a reference prosthesis seated on three-dimensional (3D) printed casts generated from digital implant scans vs stone casts made by conventional implant impressions. MATERIAL AND METHODS: A partially edentulous maxillary master cast with two internal connection implants was generated, while a reference implant-supported prosthesis was fabricated. Conventional splinted open-tray impressions were taken to create stone casts (n = 10) (control group). A digital scan was taken of the master cast using a white light intraoral optical scanner (IOS) (TRIOS, 3Shape), and a Standard Tessellation Language (STL) file was obtained. Four 3D printers were used to print the casts (n = 10 from each 3D printer): Straumann® P30+, Varseo S, Form 3b+and M2 Carbon. Accuracy of fit of the reference prosthesis on all control and test casts was assessed using the screw resistance test and radiographic test. Additionally, all casts were digitized using the same IOS, and the STL files were superimposed to the master cast STL file (reference) to evaluate the 3D accuracy with inspection Geomagic Control software using the root-mean-square (RMS) error. RESULTS: The reference prosthesis presented with clinically acceptable fit on all casts. The highest median RMS error was found in the stone cast group (94.6 µm) while the lowest median was in the M2 Carbon group (46.9 µm). The Kruskal-Wallis test revealed a statistically significant difference between the groups (p < 0.001). For post hoc comparisons, Dunn's test with the Holm-Bonferroni correction resulted in a statistically significant difference in four tests, with M2 Carbon exhibiting lower RMS error than the stone cast (p < 0.001) and P30+ (p < 0.001) groups, Form 3b exhibiting lower RMS error than the stone cast (p < 0.001) group, and Varseo S exhibiting lower RMS error than the stone cast (p = 0.006) group. CONCLUSION: Using the screw-resistance test and radiographic assessment, the reference prosthesis fit presented with clinically acceptable accuracy of fit on all casts. Printed casts from 3 different printers demonstrated statistically significant lower 3D deviations than stone casts generated using a conventional implant impression for the present partially edentulous scenario with two implants, but this did not affect prosthesis fit. CLINICAL SIGNIFICANCE: Even though there were 3D deviations between the master cast and all control and test casts generated from conventional impressions and digital scans respectively, the reference prosthesis presented with accurate fit on all casts. This indicates that there is a threshold for clinically acceptable accuracy of fit and that 3D-printed casts may be used as definitive master casts to fabricate implant-supported fixed dental prostheses for the partially edentulous anterior maxilla.

Implant survival and biologic complications of implant fixed complete dental prostheses: An up to 5-year retrospective study.

STATEMENT OF PROBLEM: Limited information is available on the association between prosthesis-associated risk factors and biologic complications for patients with implant fixed complete dental prostheses (IFCDPs). PURPOSE: The purpose of this retrospective study was to assess the implant survival and biologic complications of IFCDPs up to 5 years of follow-up. MATERIAL AND METHODS: Patients who had received IFCDPs between August 1, 2009 and August 1, 2014 were identified through an electronic health record review. Those who consented to participate in the study attended a single-visit study appointment. Clinical and radiographic examinations, intraoral photographs, and peri-implant hard and soft tissues parameters were assessed. Only prostheses which could be removed during the study visit were included. Associations between biologic complications and prosthetic factors, such as time with prosthesis in place, prosthesis material, number of implants, cantilever length, and type of prosthesis retention, were assessed. RESULTS: A total of 37 participants (mean ±standard deviation age 62.35 ±10.39 years) with 43 IFCDPs were included. None of the implants had failed, leading to an implant survival of 100% at 5.1 ±2.21 years. Ten of the prostheses were metal-ceramic (Group MC) and 33 were metal-acrylic resin (Group MR). Minor complications were more frequent than major ones. Considering minor complications, peri-implant mucositis was found in 53% of the implant sites, more often in the maxilla (P=.001). The most common major biologic complication was peri-implantitis, which affected 4.0% of the implants, more often in the mandible (P=.025). Peri-implant soft tissue hypertrophy was present 2.79 times more often (95% CI: 1.35 - 5.76, P<.003) around implants supporting metal-acrylic resin prostheses than metal-ceramic ones, with the former type also showing significantly more plaque accumulation (P<.003). CONCLUSIONS: Biologic complications such as soft tissue hypertrophy and plaque accumulation were more often associated with metal-acrylic resin prostheses. Peri-implant mucositis occurred more often under maxillary IFCDPs, while peri-implantitis appeared more common around mandibular implants.

Accuracy of Different Surgical Guide Designs for Static Computer-Assisted Implant Surgery: An In Vitro Study.

The aims of this study were to evaluate the effect of (1) the different surgical guide designs and (2) implant placement location on the accuracy of fully guided implant placement in single edentulous sites using an in vitro study model. Forty-five partially edentulous models were scanned and divided into 3 groups: group 1, tooth-supported full-arch surgical guide; group 2, 3 different tooth-supported shortened surgical guides (SSGs); and group 3, tooth-supported full-arch surgical guide with a crossbar. All surgical guides were printed and used for fully guided implant placement. A total of 180 implants (60 per group) were placed, and scan bodies were positioned on all models, and postoperative surface scan files (STL) files were obtained. Superimposition of preoperative and postoperative STL files was performed, and the accuracy of implant position was evaluated. The interaction between group and implant location was statistically significant for angle, 3D offset at the base, and at the tip (P < .001). The post-hoc tests showed a statistically significantly higher deviation for group 2 compared to group 3 for all outcomes for implants #4 (P < .05) and #7 (P < .05). There was also a statistically significant difference in all outcomes between groups 1 and 3 for implant #7 (P < .05). All surgical guide designs presented satisfactory performance with clinically acceptable levels of deviation. However, SSGs presented higher accuracy for guided implant placement in a single-edentulous site, whereas a full-arch surgical guide with a crossbar presented superior outcomes when 2 or more guided implants were placed simultaneously.

Complete Digital Workflow for Prosthesis Prototype Fabrication with the Double Digital Scanning (DDS) Technique: A Prospective Study on 16 Edentulous Maxillae.

PURPOSE: To assess the accuracy of fit of milled prosthesis prototypes for completely edentulous patients using a digital workflow. MATERIALS AND METHODS: Sixteen patients received intraoral full-arch digital scans with the double digital scanning (DDS) technique and the generated standard tessellation language (STL) files were superimposed and imported into computer-aided design software (Exocad DentalCAD, exocad GmbH, Darmstadt, Germany) for design. After the design, each master STL file was used for computer-aided manufacturing of the prosthesis prototypes through a complete digital workflow. The primary outcome was the accuracy of fit assessment of the digitally fabricated prototypes on verified patient master stone casts. Two blinded clinicians tested the accuracy of fit of the milled prosthesis prototypes on the verified master stone casts utilizing the screw-resistance test and direct observation. RESULTS: Out of the 16 digitally fabricated prototypes from intraoral full-arch digital scans, all 16 presented with an accurate fit on verified master stone casts. CONCLUSIONS: Digitally fabricated full-arch prosthesis prototypes can be generated with a complete digital workflow leading to clinically acceptable fit.

Digital Workflow in Implant Treatment Planning For Terminal Dentition Patients.

Treatment planning for the transition of patients from terminal dentition to full-arch implant rehabilitation poses challenges. Such challenges pertain to achieving the new orientation of the occlusal and esthetic plane as well as the change of vertical dimension of occlusion (VDO), while the fixed provisionalization using a digital workflow still tends to be considered complex and hard to perform. This article illustrates step-by-step the utilization of a digital workflow protocol in the treatment planning for rehabilitation of terminal dentition patients, simplifying the smile design and ensuring that fixed provisionalization serves both functional and esthetic requirements. This protocol includes facially driven, three-dimensional (3D) digital smile design and chairside mock-up restoration workflows that enable prosthetically driven assessment prior to implant treatment planning and 3D printing of surgical templates and prefabricated interim prostheses, which can predictably reduce chairside time and adjustments at the surgical and fixed provisionalization appointment.

Screw-retained surgical guide for implant placement in terminal dentition patients with existing implants.

For patients with existing implants in need of additional implant placement, the use of the existing implants for guide fixation seems to be a logical alternative. Current options for the fabrication of surgical guides involve creating surgical guides that are mucosa-borne and/or retained by fixation pins. Since these existing techniques involve inherent inaccuracies, the fabrication of surgical guides that are screw-retained at the implant- or abutment-level would eliminate the introduction of those same fundamental inaccuracies. The purpose of the present technical report is to illustrate a step-by-step digitally planned guided implant placement protocol for terminal dentition patients with salvageable existing implants requiring full-arch implant rehabilitation. The advantages of this protocol include enhancing the accuracy of guided implant placement with screw-retention versus the traditional mucosa- or fixation pin support. Thus, this simplifies the transition from failing teeth to implants by ensuring that fixed provisionalization serves both functional and esthetic requirements. This protocol can also predictably reduce chairside time and adjustments at the surgical implant placement appointment.