Books

Traditionally, metal-ceramics, metal-reinforced acrylics, and more recently full-contour or layered zirconia have been the materials of choice for definitive fixed implant-supported rehabilitations. Polymethyl Methacrylate (PMMA) is commonly used in implant dentistry for the fabrication of implant-supported interim prostheses and as milled or 3D printed prototypes. This article describes a novel protocol to prosthetically restore a completely edentulous patient following a digital workflow, with fixed, screw-retained, implant-supported prostheses fabricated from CAD/CAM milled polymethyl methacrylate (PMMA), with no metal substructure. After two years follow up in terms of esthetics, phonetics, function and biological tissue response, the outcome remains functional and free of mechanical, biomechanical or biological complications. The aim of this article is to illustrate the feasibility of using milled PMMA as viable definitive prosthetic material for the fixed implant rehabilitation of edentulous patients. Keywords: milled-PMMA, Implant-supported prostheses, long-term implant-retained restorations, CAD-CAM milled restoration

Introduction: The interforaminal region is considered more favorable for implant placement than the posterior mandible in edentulous patients, mainly because of the interference of the inferior alveolar nerve with implant placement in the severely resorbed posterior mandible. However, complications in the interforaminal region may occur due to the presence of the mandibular incisive nerve. Objective: This scoping review aims to describe the mandibular incisive nerve anatomy related to the potential interference in implant therapy. Material and methods: A comprehensive literature search was conducted in the following databases: MEDLINE (via PubMed), Web of Science, and Scopus. This scoping review was structured according to the Joanna Briggs Institute method. Results: Thirteen studies were included in the review. All the studies were observational cohort anatomical studies, carried out mainly by CBCT and on cadavers. A total of 1471 patients/cadavers were studied. The mandibular incisive nerve was presented in 87-100% of the cases, with an average length of 9.97 mm and an average diameter of 1.97 mm. The mandibular incisive nerve may be damaged during drilling and implant placement, especially using implant lengths larger than 12 mm. Conclusions: Damage to the mandibular incisive nerve due to implant placement could be present, however, it is necessary to conduct more studies focusing on assessing mandibular incisive nerve damage to understand the clinical relevance of this nerve and its associated morbidities such as neurosensorial alterations. Due to the different anatomical characteristics of this nerve, CBCT analysis is recommended for implant therapy in the anterior mandible to prevent the described complications.

Introduction: Maxillary sinus floor augmentation is a procedure known for its long-term success and predictable outcomes. However, the perforation of the Schneiderian membrane remains the most common complication associated with this procedure. Objective: This systematic review aims to determine the presence of complications during maxillary sinus floor augmentation procedures using CAD-CAM surgical templates. Material and methods: An electronic search was carried out in MEDLINE (via PubMed), Web of Science, and Scopus. A descriptive analysis of the data was performed. Studies that have performed lateral sinus floor augmentation were included in the inclusion criteria. The CAD-CAM surgical template design and the intraoperative complications were registered. Results: A total of 13 studies were included. Seven were case reports, four were case series, and two were randomized clinical trials. A total of 94 lateral SFA procedures were included (84 using CADCAM templates and 10 without using templates). Three of the 84 maxillary sinus floor augmentation procedures using a CAD-CAM template presented intraoperative complications. Conclusions: Maxillary sinus floor augmentation performed by using CAD-CAM surgical templates could be related to low rates of complications, however, due to the heterogeneity of the articles included, more standardized studies are needed to confirm these outcomes.

In der vorliegenden Fallserie sollten Einflussfaktoren für die erfolgreiche Eingliederung CAD/CAM-gefertigter implantatgetragener Provisorien untersucht werden, die auf Grundlage einer virtuell geplanten Implantatposition vor der digital navigierten Implantatinsertion hergestellt werden. Die Daten wurden an Patienten gewonnen, bei denen für eine erforderliche Einzelzahn-Implantatversorgung eine digitale Volumentomografie (DVT) und Intraoralscans in eine Implantatplanungssoftware importiert wurden. Ein Synchronisationstool stellte die Verbindung zwischen der Implantatplanungs- und der CAD-Software her, in der eine digitale diagnostische Zahnaufstellung mit passenden Zahndimensionen und adäquater Weichgewebearchitektur erstellt wurde. Anschließend wurden die virtuelle Implantatplanung abgeschlossen und die geplante Implantatposition in die CAD-Software übertragen, wo eine Restauration konstruiert und zur Herstellung geschickt wurde. Nach der navigierten Implantatinsertion wurde das vorgefertigte Provisorium noch am Tag der Implantatsetzung oder, wenn eine verzögerte Belastung oder gedeckte Implantateinheilung indiziert war, nach der Heilungsphase eingesetzt. Die Auswertung erfolgte mittels deskriptiver Statistik und Z-Test für zwei Proportionen. Insgesamt 23 Patienten mit 28 Einzelimplantatstellen erfüllten die Einschlusskriterien und wurden in die Studie inkludiert. Neunzehn individuelle Gingivaformer und 10 provisorische Kronen für insgesamt 29 Restaurationen wurden digital konstruiert und hergestellt. Für die verglichenen Variablen fanden sich keine statistisch signifikanten Unterschiede. Das Fazit: Auf einer virtuell geplanten Implantatposition basierende, individuell vorgefertigte CAD/CAM-Implantatprovisorien lassen sich erfolgreich konstruieren, herstellen und eingliedern, wenn die Implantation navigiert erfolgt. Originalpublikation: Hamilton et al. „Digitally Fabricated Provisional Implant Restorations Prior to Implant Placement: A Clinical Case Series.” (Int J Prosthodont 2022;35:94–108)1. Keywords: digitaler Workflow, CAD/CAM, Provisorium, Gingivaformer, Einzelimplantat, Implantatplanung, navigierte Implantation, DVT, Planungssoftware

This case report describes a digital workflow for a computer-aided design/computer-assisted manufacturing (CAD/CAM) healing abutment used in immediate implant placement in the esthetic zone. The design of the healing abutment was based on the existing tooth anatomy in order to provide anatomical support to the gingival tissues and to preserve the gingival contours of the natural tooth. This approach enhances the esthetic outcome of the definitive implant restoration. The surgical procedure including the guided bone regeneration is simplified, postoperative morbidity is reduced, and excessive occlusal loading during healing is limited. Keywords: CAD/CAM healing abutment, computer-guided surgery, immediate implant placement

In der dargestellten In-vitro-Studie wurde die Genauigkeit von Implantatschablonen untersucht, die mit drei unterschiedlichen 3-D-Druckverfahren hergestellt wurden. Dabei wurden jeweils zehn identische Implantatschablonen mit vier 3-D-Druckern (Hersteller und Modell zweier Drucker identisch) gedruckt. Alle Implantatschablonen wurden mit einem Referenz-Scanner gescannt und anschließend in die Darstellungssoftware importiert. Die Software berechnete über eine Best-fit-Überlagerung automatisch die dreidimensionalen Abweichungen aller Punkte. Es zeigte sich, dass alle getesteten Drucker ein hohes Maß an Genauigkeit erreichten, was den versuchsweisen Einsatz kostengünstiger Drucker bei der klinischen Herstellung von Implantatschablonen rechtfertigt. Keywords: additive Fertigung, 3-D-Druck, Stereolithografie, Genauigkeit, Implantatschablone

Purpose: This in vitro study aimed to evaluate the accuracy of surgical templates fabricated using three different 3D printing technologies. Materials and Methods: Ten identical surgical templates were printed using four 3D printers (two of an identical make and model). Each of the surgical templates was scanned by a reference scanner and then imported into the inspection software. Inspection software utilized a best-fit alignment to automatically calculate the 3D variation at all points. Results: Statistically significant differences were found among the three groups (χ2[2] = 12.880, P = .0016). Mean 3D deviation was also significantly different between the two printers of an identical make and model (χ2[1] = 8.251, P = .0041). Conclusion: All of the tested printers had a high level of accuracy in the fabrication of surgical templates, which would justify the trial of cost-effective printers for clinical fabrication of surgical implant templates.

Purpose: The purpose of this study was to examine the anatomy of the mandibular posterior region to develop an anatomical categorization for implant-prosthodontic planning. Materials and Methods: Using cone beam computed tomography scans, 313 cross-sectional views of edentulous posterior mandibular sites were evaluated with respect to the anatomical ridge morphology. Virtual implant planning was performed, and the need for bone grafting was assessed. The level of complexity for planning implants in those positions was assessed. Sites were classified as straightforward, advanced, or complex sites based on the need for bone grafting. Results: Five well-defined cross-sectional configurations were observed: straight (53.6%), oblique (26.2%), s-shape (7.4%), hourglass shape (1.9%), and basal bone (10.8%). There was a statistically significant association between the ridge shape and the feasibility of placing an implant with or without bone grafting; the straight and oblique ridge shapes were more likely to be associated with a favorable anatomy for implant placement. Conclusion: The ridge shape significantly influenced the ease or difficulty of placing an implant. The s-shape, hourglass, and basal bone posterior mandibular cross-sectional shapes were associated with a higher degree of difficulty. Keywords: dental implants, mandibular classification, posterior edentulous mandible, ridge morphology, virtual implant planning

Purpose: This review was conducted to provide information to support the establishment of clinical guidelines for the treatment of maxillary edentulism using implant-supported fixed dental prostheses. Materials and Methods: Initial efforts were directed toward a systematic review with a defined PICO question: "For maxillary edentulous patients with dental implants treated using a fixed prosthesis, what is the impact of prosthesis design on prosthesis survival and complications?" Following a title search of more than 3,000 titles identified by electronic search of PubMed, 180 articles were identified that addressed the clinical evaluation of maxillary dental implant prostheses. The broad methodologic heterogeneity and clinical variation among reports precluded this approach for a systematic review. The information was extracted using a standardized extraction table by two pairs of investigators, and the reported outcomes were then summarized according to reported outcomes for implant prostheses supported by four, six, or eight implants using unitary or segmented prostheses. Results: This review indicated that high prosthetic survival is observed using all approaches. The advantages of using fewer implants and a unitary prosthesis are revealed in the surgical phases, and complications commonly involve the fracture or detachment of acrylic teeth and reduced access for proper oral hygiene and related biologic complications. Using six implants typically involved grafting of posterior regions with advantages of reduced cantilevers and redundancy of implant support. Reduced prosthesis survival in these cases was associated with poor implant distribution. Segmented prostheses supported by six or more implants offered greater prosthetic survival, perhaps due to posterior implant placement. Advantages of a segmented prosthesis included pragmatic issues of accommodating divergent implants, attaining passive fit, combining prosthetic materials, and relative simplicity of repair. Conclusion: The existing literature demonstrated that maxillary edentulism may be treated successfully using alternative approaches involving four, six, or more implants. The procedural diagnostics, treatment, and maintenance for these different approaches all require advanced knowledge and careful communication among the therapeutic team. The prosthetic therapeutic success requires maintenance, repair, and possible multiple replacements within the patient's lifetime.

Purpose: The objectives of this case series are to describe a novel clinical approach to treat completely edentulous patients and determine its viability. Computer-guided implant planning was used to create a screwretained surgical template (ST) supported by transitional implants and a fixed screw-retained provisional prosthesis supported by the transitional implants at the time of definitive implant placement. Materials and Methods: Five patients with at least one edentulous arch were treated. After the diagnostic tooth setup was performed, a duplicate with radiopaque acrylic resin was fabricated to serve as a surgical template (ST) for the placement of screw-form transitional implants and a radiographic guide (RG). Four transitional implants were strategically placed through the guide where they would not interfere with the future definitive implants. The transitional implants were used to support the RG during computed tomographic scanning. Subsequently, the RG was converted into a second ST based on three-dimensional virtual planning. Eight implants were placed by the computer-guided system, and an immediate prefabricated fixed provisional was connected to the transitional implants. Results: All the implants included in the study achieved primary stability and osseointegrated successfully. For 4 months, the transitional implants served successfully as abutments for the provisional prosthesis. Conclusion: This innovative clinical approach overcomes the limitations of a mucosa/ bone-supported ST by offering fixed, reproducible support for the RG and ST by means of transitional implants. The delivery of a prefabricated screw-retained provisional on transitional implants allows for passive healing and minimum chairside adjustments. Keywords: computer-guided surgery, dental implants, full-arch implant rehabilitation, full-arch fixed provisionalization, transitional implant