Purpose: To evaluate the effect of cooling on the reverse torque values of different abutments in bone-level and tissue-level implants. The null hypothesis was that there would be no difference in reverse torque values of abutment screws when cooled and uncooled implant abutments were compared. Materials and Methods: Bone-level and tissue-level implants (Straumann, each n = 36) were placed in synthetic bone blocks and subdivided into three groups (each n = 12) based on the abutment type (titanium base, cementable abutment, abutment for screw-retained restorations). All abutment screws were tightened to 35 Ncm torque. In half of the implants, a dry ice rod was applied on the abutments close to the implant-abutment connection for 60 seconds before untightening the abutment screw. The remaining implant-abutment pairs were not cooled. The maximum reverse torque values were recorded using a digital torque meter. The tightening and untightening procedure was repeated three times for each implant including cooling for the test groups, resulting in 18 reverse torque values per group. Two-way analysis of variance (ANOVA) was used to analyze the effect of cooling and abutment type on the measurements. Post hoc t tests were used to make group comparisons (α = .05). The P values of post hoc tests were corrected for multiple testing using the Bonferroni-Holm method. Results: The null hypothesis was rejected. Cooling and abutment type significantly affected the reverse torque values in bone-level implants (P = .004) but not in tissue-level implants (P = .051). The reverse torque values of bone-level implants significantly decreased after cooling (20.31 ± 2.55 Ncm vs 17.61 ± 2.49 Ncm). Overall mean reverse torque values were significantly higher in bonelevel implants compared to tissue-level implants (18.96 ± 2.84 Ncm vs 16.13 ± 3.17 Ncm; P < .001). Conclusion: Cooling of the implant abutment led to a significant decrease in reverse torque values in bone-level implants and may therefore be recommended as a pretreatment before the application of procedures to remove a stuck implant part. Int J Oral Maxillofac Implants 2023;38:94–100. doi: 10.11607/jomi.9499 Schlagwörter: abutment screw, blocked implants, cryo-mechanical, maintenance, technical complications

Purpose: To compare the load-to-failure values of different ceramic CAD/CAM implant crown materials with drilled screw-access holes with and without cyclic loading applied. Materials and Methods: Forty zirconia abutments with a titanium base were pre-loaded onto implants to support maxillary right first premolar crowns milled from four different CAD/CAM ceramic materials (zirconia-reinforced lithium silicate, hybrid ceramic, lithium disilicate, and zirconia; n = 10 each). After cementing the crowns, the screw-access channels were prepared by drilling through the occlusal surfaces. Half of the specimens were subjected to cyclic loading for 5 million cycles at 2 Hz (n = 5/material). After cyclic loading, vertical loads were applied until failure. The load-to-failure values of all crowns were recorded and statistically analyzed. Two-way ANOVA was used with restricted maximum likelihood estimation and Tukey-Kramer adjustments (α = .05). Results: During cyclic loading, the zirconia abutment under one lithium disilicate specimen cracked at 2 million cycles, and a zirconia-reinforced lithium silicate crown also fractured. Results for the load-to-failure test series showed statistical differences between the materials. Zirconia resulted in significantly higher failure loads when compared to the other materials (P < .001). Cyclic loading did not significantly affect the load-to-failure values. Conclusion: Cyclic loading did not significantly influence the load to failure of any of the materials tested. Zirconia crowns with drilled screw access channels cemented on zirconia abutments with a titanium base had higher load-to-failure values compared to the other ceramic crown materials.

Purpose: To assess the effect of tooth morphology on the amount of tooth structure removal and the effect of different assessment methods on the detected amount of removed tooth structure. Materials and Methods: Eight test groups (n = 10 each) of standardized artificial teeth were prepared for partial and full crowns. All teeth were prepared by the same operator following predefined preparation parameters. Tooth structure removal was measured by using three different assessment methods: digital volumetric analysis (DVA), weight analysis (WA), and combined computer-aided manufacture-weight analysis (CAMWA). Nonparametric repeated-measures ANOVA and post hoc analyses were used to determine the influence of tooth morphology and assessment method on the detected amount of tooth structure removal. Results: For partial-crown preparations, only tooth morphology had a significant impact on the detected amount of tooth structure removal (P < .0001), but not the different assessment methods used (P = .08); tooth structure removal was not significantly different between the canine and incisor groups, but was significant for all other groupwise comparisons. For full-crown preparations, the tooth morphology (P = .047) and different assessment methods (P = .01) had an impact on the detected tooth structure removal; however, only a few groupwise comparisons reached the significance level. Conclusion: The amount of tooth structure removal depended on tooth morphology and the type of assessment method, which should be taken into account when comparing results across studies. The detected amount of tooth structure removal was below the values described in the literature independent of the assessment method used.

Purpose: To investigate the volumetric facial soft tissue changes associated with wearing complete dentures using 3D facial scans. Materials and Methods: A total of 40 volunteers (20 men and 20 women) were recruited for this study and were treated with maxillary and mandibular complete dentures. Six facial scans were taken of each subject; three scans wearing a complete denture and three without the complete denture. The 3D facial scans were taken with the mouth in three positions: closed, relaxed, and smiling. Each scan was superimposed in order to analyze and quantify linear measurements involving 14 soft tissue landmarks and the total volume that the subject gained with the prosthesis. Results: Three variables were evaluated in each analysis: gender, mouth position, and age. In the analysis of the soft tissue landmarks, there was a significant effect of age, with patients > 75 years showing the greatest changes (P < .05). The landmarks that showed the most changes were those located around the mouth. In the volumetric analysis, the variable with the highest influence was gender, with men gaining more volume than women (P < .05). Conclusion: Complete dentures have a significant effect on volumetric changes in perioral tissues. These changes are more marked in patients > 75 years. Compared to women, men depicted greater volumetric changes with complete dentures. These results provide a new avenue for clinicians and developers using facial scans to design future restorations for edentulous patients.

Der Fallbericht dokumentiert die konventionelle und die digitale Herstellungsmethode von Klammerprothesen. Es werden Chancen und Grenzen des digitalen Herstellungsverfahrens aufgezeigt. Zu den Chancen gehören der geringere Zeit- und Kostenaufwand, allerdings ist die Passgenauigkeit möglicherweise eingeschränkt. Schlagwörter: Klammerprothese, CAD/CAM, digitaler Workflow, Kommunikation, SLM

Ziel: Dieser Fallbericht beschreibt einen digitalen Workflow für die prothetisch orientierte Behandlungsplanung, Implantatinsertion und Herstellung zweier verschraubter, implantatgetragener Full-arch-Brücken bei einem zahnlosen Patienten. Ziel der Kasuistik ist es, die digitalen Arbeitsschritte des Workflows, insbesondere die Scantechnik für die Erfassung der zentrischen Kondylenposition, anhand eines klinischen Falls zu zeigen und zu erläutern. Außerdem werden die Grenzen des Workflows diskutiert.Material und Methoden: Die statische computergestützte Implantation (static Computer-aided Implant Surgery, s-CAIS) wurde auf Basis einer digitalen Volumentomografie, eines Intraoralscans und eines digitalen Bissregistrats dreidimensional geplant. Mittels s-CAIS wurden vier Implantate im Unter- und sechs Implantate im Oberkiefer des unbezahnten Patienten platziert. Die definitiven Full-arch-Restaurationen aus monolithischem Zirkonoxid wurden in einem digitalen Workflow hergestellt, der die zuvor benutzte Röntgenschablone in modifizierter Form für die digitale Kieferrelationsbestimmung nutzte.Schlussfolgerungen: Die Entwicklung digitaler Methoden ermöglicht die Konstruktion, Verarbeitung und Herstellung implantatgetragener Full-arch-Versorgungen in einem chirurgischen, prothetischen und zahntechnischen Workflow auf Grundlage eines dreidimensionalen Backward-Planning. Anhand der digitalen prothetischen Aufstellung lassen sich mittels CAD/CAM-Technik intraorale Prototypen herstellen, die als Vorlage für die definitive monolithische Zirkonoxid-Suprastruktur dienen. Schlagwörter: Backward Planning, unbezahnt, implantatgetragen, Full-arch-Brücke, Oberkiefer, Unterkiefer, CAD/CAM, monolithisch, Zirkonoxid, Röntgenschablone

Die Implantattherapie bei älteren Menschen bedarf einer gezielten Planung. Dabei spielt die Unterscheidung zwischen dem dritten und vierten Lebensabschnitt für die Behandlungsplanung und die anschließende zahnärztliche Betreuung eine wichtige Rolle, da diese Patientengruppen sich fundamental voneinander unterscheiden. Für Menschen des dritten Lebensabschnitts steht das gesamte Spektrum der zahnärztlichen Implantologie zur Verfügung, allerdings müssen chronische Erkrankungen, Medikation und manuelle Geschicklichkeit beachtet werden. Da dentale Implantate meist deutlich länger als 20 Jahre im Mund verbleiben, muss prospektiv die zukünftige Abnahme der biologischen, sozialen und kognitiven Funktionen bei der Planung berücksichtigt werden. Im vierten Lebensabschnitt ist das Leben von der Abhängigkeit bei den Aktivitäten des täglichen Lebens (ADL), Multimorbidität, Polypharmazie und Institutionalisierung bestimmt. Es gibt fast keine wissenschaftliche Evidenz zur Implantattherapie dieser Patientengruppe. Die wenigen vorhandenen Studien zeigen eine sehr hohe Implantatüberlebensrate und es gibt Hinweise auf verringerte akute periimplantäre Entzündungsreaktionen. Gerade Patienten in der vierten Lebensphase könnten am meisten vom funktionellen Gewinn einer implantatstabiliserten Totalprothese profitieren, wenn die muskulären Fähigkeiten zur Stabilisierung einer Prothese nachlassen. Allerdings müssen Handhabung, Nachsorge und tägliche Pflege gesichert werden, bevor mit einer solchen Therapie im Sinne des Nichtschadensgebots begonnen wird. Menschen im palliativen Kontext weisen zunehmend Implantate auf, die die Betroffenen und die Pflegenden vor große Herausforderungen stellen können. Hier müssen die Implantatprothesen rechtzeitig „rückgebaut“ werden, um Schmerzen und Infektionen zu vermeiden. Manuskripteingang: 06.01.2021, Annahme: 19.02.2021 Schlagwörter: Implantologie, Gerodontologie, dritter Lebensabschnitt, vierter Lebensabschnitt, chirurgische Strategien, prothetische Strategien

With the so-called "baby boomer" generation reaching retirement, a new challenge in implant dentistry has emerged. Predominantly, tooth loss occurs later in life, accompanied by increased demand for partial dental prostheses. edentulous patients are more difficult to treat due to advanced age, functional dependence, illness, and financial instability. Prosthetic planning becomes more complex as interindividual diversity increases with age. Considerations such as resilience, physical and mental status, medical history, and drug prescriptions must be individually assessed. Treatment planning and restoration design should fulfill both functional requirements and esthetic demands. Prosthesis design should prevent further harm to the patient. This tertiary prevention approach should prevent local inflammation of the oral tissues, but also prevent secondary systemic infections, such as aspiration pneumonia. There are many prosthetic options for partially or fully edentulous patients. Dental technicians should be aware of the advantages and disadvantages of the various treatment concepts and materials, and contribute professional knowledge to the patient, dentist, and often thirdparty milling centers. Using CAD/CAM technology, customized attachments and prostheses can be individualized according to each patient's requirements. Utilizing a combination of manual and digital production techniques, oral reconstructions can be rationally manufactured. The duration of implant osseointegration remains unknown, but reports of up to 30 years' follow-up are emerging. hence, the environment of the implant - the patient - will change significantly, and implant restorations should be flexibly designed to meet the changing needs of an aging patient. This "back-off strategy" should be implemented, and prostheses should be continuously subjected to critical reevaluations and adaptation. Schlagwörter: Gerodontology, prostheses, edentulous, dental laboratory work

Full-arch rehabilitation of patients with severe tooth wear due to parafunctional behavior is a challenge for dentists and dental technicians, especially when a highly esthetic outcome is desired. A variety of different treatment options and prosthetic materials are available for such a clinical undertaking. The ongoing progress of computer-aided design/computer-assisted manufacture technologies in combination with all-ceramic materials provides a predictable workflow for these complex cases. This case history report describes a comprehensive, stepby- step treatment protocol leading to an optimally predictable treatment outcome for an esthetically compromised patient.