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It is common knowledge that dental implants should not be inserted in adolescents, before completion of skeletal growth, because they behave as ankylosed teeth and remain in a fixed position while the surrounding bone and teeth are still developing, with consequential worsening esthetic damage. However, there is growing evidence that this phenomenon may continue throughout life in a large number of adult patients, although with a great variability in onset, progression, and extent. Infraocclusion and interproximal contact loss are the more common complications, and the majority of clinically significant cases are located in the anterior maxilla. The esthetic impact is mostly minimal, but in some cases the patient's smile may be severely compromised. Therefore, adult patients need to be informed when dental implants are considered to replace anterior missing teeth. Keywords: adult alveolar growth, dental implants, infraocclusion

Several studies have clearly shown that osseointegrated implants, when inserted in growing bone, such as in adolescents, do not follow the eruptive path of adjacent teeth; instead, they act like ankylosed teeth, remaining in a stationary position for the lifetime, thus developing a progressive infraposition of the implant-supported crown. However, further studies have demonstrated that similar changes also occur in adult patients, although mostly in a small amount and over long time spans. Here the case of a female patient aged 35 years is presented, in which infraposition of the maxillary central incisor developed in a very short time (15 months). The treatment provided was a combined orthodontic/prosthetic approach with a 4-year follow-up. Keywords: craniofacial growth, implant crown, infraposition, orthodontic intrusion

Aim: The purpose of this prospective cohort study was to investigate, over an 18-month period, soft and hard tissue response to a transmucosal implant with a convergent collar inserted in the anterior maxillary esthetic area. Materials and methods: From June 2013 to January 2014, 14 consecutive patients were enrolled (7 men and 7 women; mean age 63.7 ± 14 years) with 20 implants, needing at least one implant-supported restoration between the canines in the maxillary anterior esthetic area. Six months after hopeless tooth extraction and an alveolar socket graft, a transmucosal-type implant with convergent collar walls was inserted in a midcrestal position with mini-flap surgery. An impression was taken 2 months later, and a definitive abutment with a provisional restoration was positioned. The final restoration was seated 2 weeks later. Clinical parameters, photographs, radiographs, and impressions were taken at this timepoint, and after 6 and 18 months. Using dedicated software, radiographic analysis (to detect marginal bone-level changes) and cast analysis (to detect soft tissue vertical and horizontal changes) were performed. Results: At the 18-month follow-up, all implants were clinically osseointegrated, stable, and showed no sign of infection. At baseline, interproximal radiographs revealed no bone defect around the implant. After an initial minimal bone loss (0.09 ± 0.144 mm), radiographic analysis showed a stable condition of bone remodeling (mean value 0.09 ± 0.08; range 0.0 to 0.5 mm) at the 18-month follow-up. No statistically significant horizontal dimensional changes of the alveolar ridge were observed between each timepoint. Mean soft tissue levels significantly improved between baseline and 18 months. The mean heights of the mesial papilla (MP) and distal papilla (DP) changes were 0.38 ± 0.22 and 0.47 ± 0.31, respectively. The level of the labial gingival margin (LGM) was 1.01 ± 0.63. Periodontal parameters never exceeded the physiological levels. Conclusions: Within the limitations of this preliminary study, the analyzed implants produced positive results in these esthetically demanding cases. This outcome should encourage long-term studies in order to assess, through controlled clinical trials, whether this convergent collar design offers advantages over other designs. Furthermore, due to the peculiar crestal module, together with the use of delayed implant insertion and a postextraction ridge preservation technique with biomimetic hydroxyapatite, the analyzed implants seem to help prevent the negative bone remodeling typically associated with two-piece implant systems, but without the well-known drawbacks of traditionally designed transmucosal implants. Therefore, wherever crestal bone preservation is a critical issue for clinical success in the anterior maxillary area can be considered of particular interest.

Ziel: Ziel dieser prospektiven Kohortenstudie war es, die Weich- und Hartgewebsreaktion auf ein transmukosales Implantat mit konvergierendem Implantathals im Frontzahnbereich des Oberkiefers über einen Zeitraum von 18 Monaten zu untersuchen. Material und Methode: Von Juni 2013 bis Januar 2014 wurden nacheinander 14 Patienten (sieben Frauen und sieben Männer, Durchschnittsalter 63,7 ± 14 Jahre) aufgenommen. Insgesamt hatten sie 20 Implantate und brauchten mindestens eine implantatgetragene Restauration im oberen Frontzahnbereich (Zähne 13 bis 23). Sechs Monate nach der Extraktion eines nicht erhaltungswürdigen Zahns mit gleichzeitiger Socket Preservation wurde nach der Präparation von Minilappen ein transmukosales Implantat mit konvergierendem Hals in der Mitte des Kieferkamms gesetzt. Zwei Monate postoperativ wurde eine Abformung durchgeführt und ein definitives Abutment mit einer provisorischen Versorgung eingesetzt. Die definitive Restauration wurde zwei Wochen später eingegliedert. Zu diesem Zeitpunkt sowie nach sechs und nach 18 Monaten wurden klinische Parameter bestimmt und Fotografien, Röntgenbilder sowie Abformungen angefertigt. Die Röntgenanalyse (um Veränderungen am Knochenniveau festzustellen) und Modellanalyse (um horizontale und vertikale Veränderungen des Weichgewebes festzustellen) erfolgten mithilfe einer speziellen Software. Ergebnis: Bei der Kontrolle nach 18 Monaten waren alle Implantate osseointegriert, stabil und entzündungsfrei. Zu Untersuchungsbeginn zeigten die Röntgenbilder keinen Knochendefekt um das Implantat. Nach einem geringfügigen initialen Knochenverlust (0,09 ± 0,144 mm) zeigte die Röntgenanalyse nach 18 Monaten eine stabile Knochenremodellierung (Durchschnitt: 0,09 ± 0,08; Bereich: 0,0 bis 0,5 mm). Zwischen allen Untersuchungszeitpunkten veränderte sich die horizontale Kammbreite statistisch signifikant. Das mittlere Weichgewebsniveau verbesserte sich zwischen Studienbeginn und der Kontrolle nach 18 Monaten signifikant. Die durchschnittliche Höhe der mesialen Papille nahm um 0,38 ± 0,22 mm, die der distalen Papille um 0,47 ± 0,31 mm zu. Das Niveau des labialen Mukosarands erhöhte sich um 1,01 ± 0,63 mm. Die parodontalen Parameter lagen immer im Rahmen des physiologischen Bereichs. Schlussfolgerung: Innerhalb der Grenzen dieser Präliminarstudie wurden mit den untersuchten Implantaten in der gegebenen ästhetisch anspruchsvollen Situation positive Resultate erreicht. Dieses Ergebnis sollte Langzeituntersuchungen anregen, bei denen mithilfe kontrollierter klinischer Studien ermittelt wird, ob die konvergierende Implantathalsform Vorteile gegenüber anderen Designs bietet. Die untersuchten Implantate können offenbar dank der speziellen Halsform die Knochenresorption, wie sie für zweiteilige Implantate typisch ist, verhindern. Voraussetzungen hierfür waren auch die Socket Preservation mit biomimetischem Hydroxylapatit nach der Extraktion und die verzögerte Implantation. Die bekannten Nachteile herkömmlich geformter transmukosaler Implantate zeigten sich nicht. Wenn der Erhalt des Knochenkamms für einen Behandlungserfolg im Frontzahnbereich des Oberkiefers besonders wichtig ist, können die untersuchten Implantate deshalb eine interessante Option sein.

Zementierte Implantatrestaurationen werden heute von vielen Zahnärzten regelmäßig verwendet. Das herkömmliche Abutmentdesign ähnelt der Kronenpräparation eines natürlichen Zahns mit vergleichbaren Konvergenzwinkeln und einem als Hohlkehle gestalteten Präparationsrand. Eine häufige Komplikation an Implantatrestaurationen im ästhetischen Bereich sind im Lauf der Zeit auftretende Rezessionen der labialen Gingiva. Neben anderen Faktoren spielt vermutlich vor allem die Abutmentform eine wichtige Rolle für die Stabilität des Gingivarands in der ästhetischen Zone. Bislang wurde dieser Aspekt allerdings noch nicht eingehend untersucht. Kürzlich wurde unter der Bezeichnung "biologisch orientierte Präparationstechnik" (biologically oriented preparation technique, BOPT) ein prothetisches Konzept vorgeschlagen, bei dem Federrandpräparationen an natürlichen Pfeilerzähnen angelegt wurden. Es wird angenommen, dass dieses Präparationsdesign auch bei Implantatabutments die langfristige Stabilität des Gingivarands verbessert. Gegenwärtig gibt es jedoch noch keinen wissenschaftlichen Nachweis, der diese Behauptung stützt. Vielmehr dürfte es bedenklich sein, ein solches Design in allen klinischen Situationen zu verwenden. Mit Rücksicht auf diese Überlegungen soll in diesem Beitrag das "Hybridabutment-Design" (HAD) vorgestellt werden. Dieses neue Design kombiniert beide Möglichkeiten: die Federrandpräparation bukkal und die Präparationsgrenze mit Hohlkehle lingual. Außerdem wird eine Begründung für die Anwendung unterschiedlicher Abutmentdesigns in verschiedenen klinischen Situationen vorgestellt.

Cemented implant restorations are widely used by many dentists. The traditional abutment design resembles a natural tooth prepared for a crown with a similar taper and a chamfer finish line. A frequent complication associated with implant restorations in the esthetic zones is the recession of buccal gingiva over time. Abutment morphology, among several other prosthetic factors, may play an important role in the stability of the gingival margin in esthetically sensitive areas, but this has never been thoroughly analyzed. Recently, a prosthetic technique called biologically oriented preparation technique (BOPT) has been proposed, which utilizes a feather-edge preparation on natural abutments, and it has been claimed that applying the concepts of this technique to implant abutments could improve long-term gingival margin stability. At present, there is no available evidence to confirm this claim. Moreover, some concerns may arise if this particular design is implemented in every clinical situation. With these considerations in mind, this article proposes the "hybrid abutment" design (HAD), a new design that includes a combination of the two types of features - a feather edge on the buccal side, and a chamfer finish line on the lingual side. The article also presents a rationale for the use of different abutment designs for different situations.

Purpose: The aim of this randomised clinical trial was to evaluate the influence of restoration on marginal bone loss (MBL) using immediately definitive abutments (one abutment-one time concept) versus provisional abutments later replaced by definitive abutments. Materials and methods: In three private clinics, 32 patients with 32 hopeless maxillary premolars were selected for post-extractive implant-supported immediate restoration and randomised to provisional abutment (PA) and definitive abutment (DA) groups, 16 sites in each group. After tooth extraction, 7 patients had to be excluded for buccal wall fracture at tooth extraction or lack of sufficient primary implant stability (< 35 Ncm). The remaining 25 patients (10 PA, 15 DA) received a post-extractive wide-diameter implant. Immediately after insertion, the PA group were immediately restored using a platform-switched provisional titanium abutment. In the DA group, definitive platform-switched titanium abutments were tightened. In both groups, provisional crowns were adapted, avoiding occlusal contacts. All implants were definitively restored after 3 months. In the PA group, a traditional impression technique with coping transfer was adopted, dis/reconnecting abutments several times; in the DA group, metal prefabricated copings were used and final restorations were seated, avoiding abutment disconnection. Digital standardised periapical radiographs using a customised film holder were recorded at baseline (T0 = implant insertion), final restoration (T1 = 3 months later), and at 18-month (T2) and 3-year (T3) follow-ups. The MBL was evaluated with a computerised measuring technique and digital subtraction radiography (DSR) software was used to evaluate radiographic density. Results: At the 3-year follow-up a success rate of 100% in both groups was reported. In the PA group, peri-implant bone resorption was 0.36 mm at T1, 0.43 mm at T2, and 0.55 mm at T3. In the DA group, peri-implant bone resorption was 0.35 mm at T1, 0.33 mm at T2, and 0.34 mm at T3. Statistically significant lower bone losses were found at T2 (0.1 mm) and T3 (0.2 mm) for the DA group. At T3, significantly higher DSR values around implant necks were recorded in the DA group (72 ± 5.0) when compared with the PA group (52 ± 9.5). Conclusions: The current trial suggests that the 'one abutment-one time' concept might be a possible additional strategy in post-extraction immediately restored platform-switched single implants to further minimise peri-implant crestal bone resorption, although a 0.2 mm difference may not have any clinical effect. Additional clinical trials with larger groups of patients should be performed to better investigate this hypothesis. Keywords: bone preservation, definitive abutment, dental implant, immediate loading, platform switching

The purpose of this study was to present a new laboratory technique for cementable implant-supported restorations and to evaluate its efficacy in reducing chair time for both patients and clinicians, while maintaining the precision of an indirect procedure for crown fabrication. The technique consisted of the duplication of the implant portion of a working cast prepared using double-pour or plastic base die systems for single or multiple crowns. For this purpose, a flask previously intended for the production of ceramic inlays and onlays was used. Duplication was obtained using a high-precision addition silicon material and a low-shrinkage polyurethane resin. The duplicated implant abutment was used to finalize the fixed partial denture restorations after the originals were delivered to the patients. Fifty abutments were tested consecutively. The castings (19 single crowns, 31 fixed partial dentures) produced on the original abutments were seated on the duplicate abutments and evaluated by two prosthodontists and two dental technicians using a visual inspection method (laboratory microscope at 16X magnification). Forty-eight restorations were "good" (completely seated, no marginal opening) and 2 were "acceptable" (incomplete seating but amendable), with a 98% success rate. The technique presented demonstrates efficacy and predictability in reducing the number of clinical sessions for delivering precisely fitting cementable implant-supported restorations.

The use of a narrower-diameter abutment over a larger-diameter implant platform has been shown to decrease peri-implant bone resorption. This technique, known as platform switching, shifts the implant-abutment microgap inward. The aim of this study was to examine whether shifting the microgap further inward by increasing the discrepancy between the implant platform and abutment diameter would result in a decrease in crestal bone loss. Ten patients requiring mandibular or maxillary implant restorations were included in this study. The inclusion criteria called for an alveolar crest thickness of at least 8.0 mm at the implant placement site. Fifteen Certain PREVAIL implants with a body diameter of 5.0 mm, an expanded platform feature with a maximum diameter of 5.8 mm at the collar, and a prosthetic seating surface of 5.0 mm were used in lengths of 8.5, 10.0, 11.5, or 13.0 mm. The implants were connected to 4.1-mm healing abutments in a single-stage protocol. Periapical radiographs taken before and immediately after surgery, 8 weeks after implant placement, immediately after definitive prosthesis insertion, and at 12 and 18 months after loading revealed an average peri-implant bone loss of 0.30 mm. Increasing the discrepancy between the diameter of the implant platform and the restorative abutment may lead to a decrease in the amount of subsequent coronal bone loss.

Platform switching is a concept recently introduced in implant dentistry. It is intended to reduce the crestal bone loss that is commonly found around implants exposed to the oral environment. The aim of this study was to examine biopsy specimens to help explain the biologic processes occurring around a platformswitched implant. A mandibular implant was removed 2 months after placement because of prosthetic rehabilitation difficulties. The implant was then sectioned and subjected to histologic and histomorphometric analysis. An inflammatory connective tissue infiltrate was localized over the entire surface of the implant platform and approximately 0.35 mm coronal to the implant-abutment junction, along the healing abutment. A possible reason for bone preservation around a platformswitched implant may lie in the inward shift of the inflammatory connective tissue zone at the implant-abutment junction, which reduces its injurious effect on the alveolar bone.