Libros

Aim: The aim of this scoping review was to identify the scientific evidence related to the utilization of Optical See- Through Head-Mounted Display (OST-HMD) in dentistry, and to determine future research needs. Methods: The research question was formulated using the "Population" (P), "Concept" (Cpt), and "Context" (Cxt) framework for scoping reviews. Existing literature was designated as P, OST-HMD as Cpt, and Dentistry as Cxt. An electronic search was conducted in PubMed, Embase, Web of Science, and CENTRAL. Two authors independently screened titles and abstracts and performed the full-text analysis. Results: The search identified 286 titles after removing duplicates. Nine studies, involving 138 participants and 1760 performed tests were included in this scoping review. Seven of the articles were preclinical studies, one was a survey, and one was a clinical trial. The included manuscripts covered various dental fields: three studies in orthodontics, two in oral surgery, two in conservative dentistry, one in general dentistry, and the remaining one in prosthodontics. Five articles focused on educational purposes. Two brands of OST-HMD were used: in eight studies HoloLens Microsoft was used, while Google Glass was utilized in one article. Conclusions: The overall number of included studies was low; therefore, the available data from this review cannot yet support an evidence-based recommendation for the clinical use of OST-HMDs. However, the existing preclinical data indicate a significant capacity for clinical and educational implementation. Further adoption of these devices will facilitate more reliable and objective quality and performance assessments, as well as more direct comparisons with conventional workflows. More clinical studies must be conducted to substantiate the potential benefits and reliability for patients and clinicians. Palabras clave: augmented reality, dental education, digital dentistry, mixed reality, scoping review, virtual reality

Purpose: To evaluate the suitability of maxillary premolars for immediate implant placement (IIP). Based on prosthetically driven treatment planning, a simple classification system was developed. Materials and Methods: In total, 150 CBCTs of maxillary first premolars were analyzed in BlueskyBio software. The topographic position of the tooth was determined by analyzing the dimensions of the buccal and lingual cortical plates, the distance between the buccolingual plates, and the residual bone height from the root apex to the floor of the sinus. Virtual placement of an implant was carried out such that the implant would be positioned 1 mm apical to the buccal bone crest, would engage 3 mm of bone apical to the root apex, and would have a trajectory so that the abutment access was from the central fossa. Four categories were identified, and the classification was proposed. Results: It was observed that 74% of cases had buccal bone < 1 mm and 26% had buccal bone > 1 mm. It was also observed that 79% cases had an average distance > 3 mm between the root apex and maxillary sinus (with 21% of cases < 3 mm). The categorizations of implant placement were as follows: Type 1 (24%), Type 2 (56.6%), Type 3 (43.3%), and Type 4 (0%). Conclusions: In the majority of maxillary first premolars, IIP is possible with the implants to be placed in the palatal sockets or the furcation area. In cases where the buccal plate thickness is inadequate, simultaneous grafting should be considered between the implant and buccal plate.

Purpose: To utilise high-frequency ultrasound echo intensity as a method for identifying a safe harvesting zone and assessing tissue thickness, density and vascularisation in the palatal region for soft tissue harvesting. Materials and methods: Four consecutive patients requiring soft tissue augmentation were recruited. Optical scans were taken and imported into design software, where customised guides were developed based on the patient’s palatal anatomy and the harvesting zone. The guides were tailored to fit the shape of the ultrasound probe. They were 3D printed and allowed for a standardised examination of the palate, the identification of a safe harvesting zone and the evaluation of tissue thickness, quality and vascularisation using high-frequency ultrasound. Following these steps and using an echo-harvesting guide, a de-epithelialised free gingival graft was obtained, ensuring preservation of the main vascular flow while avoiding fatty or glandular tissues. Results: In all four cases, high-frequency ultrasound scans were successfully obtained and the mean measured soft tissue thickness increased from 3.2 mm (anterior) to 6.0 mm (posterior), with a mean transversal increase from 0.9 to 6.0 mm. Ultrasound imaging revealed a layer of hypoechogenic fatty/glandular tissue located 3 to 4 mm beneath the epithelial layer. Using colour Doppler analysis, the vascular flow was identified and mapped to help design a safe harvesting zone. The tissue density, evaluated using a grayscale analysis, showed hypoechogenicity corresponding to fatty/glandular tissues and areas with blood vessels, whereas dense connective tissue appeared isoechoic. This differentiation allowed for precise localisation of the safe harvesting zone, an optimal zone for connective tissue harvesting, while ensuring that regions with higher fat/glandular content and/or large vascular structures were avoided. Conclusion: The echo-guided harvesting approach is a promising technique for soft tissue palatal harvesting, enabling clinicians to identify a standardised safe zone away from major blood vessels when assessing tissue quality and quantity. This approach enhances surgical precision and control, and facilitates preoperative planning for alternative treatments when graft size or tissue quality or quantity are inadequate due to proximity to the greater palatine artery. It is crucial to note that a learning curve is required to interpret the obtained images accurately and integrate this tool into daily clinical practice. Palabras clave: connective tissue graft, de-epithelialised gingival graft, soft tissue augmentation, soft tissue harvesting, ultrasonography The authors declare there are no conflicts of interest relating to this study.

Multiple disconnection and reconnection of abutments has been known to affect the mucosal barrier around implants, leading to marginal bone loss (MBL). This clinical report describes a novel technique that amalgamates the benefits of digital technologies including the fabrication of surgical guides for implant placement, customized hybrid zirconia abutments, and all-ceramic lithium disilicate crowns prior to implant placement. Correct 3D implant positioning, along with immediate placement of the definitive hybrid customized abutment and a lithium disilicate crown, have the potential to reduce treatment time, visits, and costs while delivering optimal esthetic outcomes.

Aim: To evaluate the fracture load and type of failure of two different monolithic restorative materials bonded to standardized titanium bases and fabricated by two different procedures regarding the bonding interface. Materials and methods: All screw-retained implant crown specimens (n = 40), subjected to fatigue by thermomechanical loading, differed in the restorative material (lithium disilicate [LDS] or polymer-infiltrated ceramic network [PICN], referred to as ‘hybrid ceramic’ [HYC]) and the interface type between the restorative material and the titanium base abutment (prefabricated ex-factory or produced during a CAM-milling procedure). This resulted in the following groups (n = 10/group): 1) LDS-M: lithium disilicate crown with a CAM-milled interface; 2) LDS-P: lithium disilicate crown with a prefabricated interface; 3) HYC-M: PICN crown with a CAM-milled interface; and 4) HYC-P: PICN crown with a prefabricated interface. Aged specimens underwent static fracture load testing. The load (N) at which the initial crack occurred was denoted as Finitial, and the maximal load (N) at which the restorations fractured as Fmax. All specimens were examined under a stereomicroscope to determine the failure mode. Results: The median Finitial values were 180 N for LDS-M, 343 N for LDS-P, 340 N for HYC-M, and 190 N for HYC-P. The median Fmax values were 1822 N for LDS-M, 2039 N for LDS-P, 1454 N for HYC-M, and 1581 N for HYC-P. The intergroup differences were significant for Finitial (KW: P = 0.0042) and for Fmax (KW: P = 0.0010). The failure types also showed differences between the restorative groups. Conclusions: The choice of restorative material had a stronger influence on the fracture load than the abutment interface workflow. Lithium disilicate showed the highest load for initial crack appearance (Finitial) and for complete fracture of the restoration (Fmax). Palabras clave: lithium disilicate, dental materials, polymer-infiltrated ceramic network, thermomechanical aging, fracture load, failure mode, prosthetic dentistry, restorative material, abutment interface

Die wissenschaftliche Evidenz für Zirkonoxidimplantate ist in den letzten Jahren erheblich gestiegen. Mittlerweile liegen Daten aus klinischen Studien vor, die eine Beobachtungszeit von 5−7 Jahren umfassen. Dennoch fehlen weiterhin randomisierte klinische Studien, die den Einsatz von Zirkonoxidimplantaten in verschiedenen klinischen Indikationen vergleichen. Es gibt bislang keine Studie, die den direkten Vergleich zwischen kurzen und längeren Zirkonoxidimplantaten untersucht. Ebenso fehlen klinische Daten über den Einsatz von kurzen Zirkonoxidimplantaten. Als kurze Implantate sind Implantate mit einer Länge von 6 mm oder weniger definiert. 8 mm „kurze“ Zirkonoxidimplantate können jedoch erfolgreich verwendet werden. Zudem zeigen Ergebnisse aus Kohortenstudien, dass die Implantatlänge keinen Einfluss auf das marginale Knochenniveau hat. Kurze Zirkonoxidimplantate könnten im Kieferkamm mit einer reduzierten vertikalen Höhe eine kostengünstige Behandlungsoption mit geringerer Morbidität darstellen, wenn dadurch eine aufwendige Knochenaugmentation verhindert werden kann. In Situationen, in denen ausreichend vertikale Höhe vorhanden ist, scheint die Verwendung von Implantaten mit Standardlänge die sicherere Option zu sein. Manuskripteingang: 08.07.2023, Annahme: 18.08.2023 Palabras clave: Zirkonoxidimplantate, vollkeramische Restaurationen, metallfreie Restaurationen, kurze Implantate, wissenschaftliche Evidenz

Ziel: Ziel der vorliegenden retrospektiven Fallserie war die Einführung eines minimalinvasiven zweistufigen lappenfreien Verfahrens für die Kronenverlängerung, das die Gingivektomie vermeidet oder minimiert, indem die Reduktion der Knochenhöhe mithilfe einer Tunnelpräparation vorgenommen wird. Material und Methode: In diese Studie wurden neun Patientinnen und ein Patient (Altersmedian: 46,6 Jahre, Bereich: 26,9 bis 71,6 Jahre) eingeschlossen. Die Indikationen für die Durchführung der Kronenverlängerung waren: ästhetisch zu kurze Kronen (n = 5), Asymmetrie der Gingivahöhen (n = 2) und die Kombination aus diesen Indikationen (n = 3). Alle Behandelten wiesen einen dicken gingivalen Phänotyp auf, und die mittlere Anzahl der in den Eingriff einbezogenen Zähne betrug 3,7 (Bereich: 2 bis 8 Zähne). Drei Teilnehmende erhielten sechs Wochen nach der Kronenverlängerung eine zusätzliche Gingivektomie. Ergebnisse: Die Ergebnisse erfüllten in ästhetischer und funktioneller Hinsicht die Erwartungen der Behandelten und des Zahnarztes. Schlussfolgerung: Das minimalinvasive zweistufige Kronenverlängerungsverfahren unter Anwendung einer Tunneltechnik kann auch ohne offenen Lappen und zusätzliche Gingivektomie vorhersagbare ästhetische Ergebnisse liefern. Prospektive klinische Studien sind nötig, um die Technik zu validieren.

Aim: The purpose of the present retrospective case series was to introduce a minimally invasive two-stage flapless crown lengthening procedure where a gingivectomy was avoided or minimized by reducing the bone height through a tunneling technique. Materials and method: Ten patients (median age 46.6 years, range 26.9 to 71.6 years) were included in the study. The indications for performing a crown lengthening procedure were esthetically short clinical crowns (n = 5), asymmetry of the gingival margin level (n = 2), and both esthetically short clinical crowns and asymmetry of the gingival margin level (n = 3). All the patients presented a thick gingival phenotype, and the mean number of operated teeth per patient was 3.7 (range 2 to 8 teeth). Three patients underwent an additional gingivectomy 6 weeks after the crown lengthening procedure. Results: The esthetic and functional outcome of the treatments fulfilled the patients’ and dentist’s expectations. Conclusion: A minimally invasive two-stage crown lengthening procedure applying a tunneling technique has the potential to achieve predictable esthetic outcomes without an open-flap approach and an additional gingivectomy. However, prospective clinical studies are needed to validate this technique.