”one abutment-one time”: optimizing platform-switching concept. 3-year controlled prospective study

Background: The “platform-switching” concept showed better peri-implant crestal bone preservation in post-extraction immediately restored implants when compared to matching diameter abutment configuration. However repeated abutment dis/reconnections during restorative procedures from provisional to final crown could produce apical shifting of peri-implant tissues. Aim: Aim of this controlled prospective study was to evaluate on bone levels (MBL) the influence of restoration using immediately definitive abutments (one abutment-one time concept) versus provisional abutment later replaced by a definitive abutment. Materials and methods: 26 patients with 26 hopeless maxillary premolars received a post-extraction wide diameter implant. Immediately after insertion, 11 patients (Control Group, CG) were immediately restored using a platform-switched provisional titanium abutment. In 15 patients (Test Group, TG), 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: for the final impression, in CG, traditional impression technique with coping transfer was adopted, dis/reconnecting abutments several times; in TG, metal prefabricated coping was used and final restoration was seated avoiding abutment disconnection. Digital standardized periapical radiographs using a customized film holder were recorded at baseline (T 0 = implant insertion), final restoration (T1=3 months after), 18 (T2) and 36 months (T3) follow-ups. The MBL was evaluated with a computerized measuring technique applied to radiographs. Digital subtraction radiography software was used to evaluate radiographic density of bone tissue around implants. The Student’s t-Test (confidence level: P<0.05) was selected to identify differences between test and control groups at different follow-ups concerning MBL values. Results: In the CG peri-implant bone resorption was 0.41mm (SD=0.15mm) at T1, 0.38mm (SD=0.12mm) at T2, 0.53mm (SD = 0.13mm) at T3. In the TG, on average, peri-implant bone resorption was 0.59 mm (SD=0.19mm) at T1, 0.31mm (SD=0.11mm) at T2, 0.32mm (SD = 0.16mm) at T3. Statistically significant difference between groups was only found at T3. At the same follow-up period, higher density in radiographic bone appearance around implant neck was recorded in the TG compared to CG. Conclusions and clinical implications: The implant/abutment stability following the minimally invasive prosthetic strategy adopted (“platform-switching” and “one abutment- one time”) could longitudinally produce additional hard tissue preservation compared to implants restored according to “platform-switching” only. Despite of the encouraging data reported, however, controlled clinical studies on larger patient sample and histologic investigations are required to confirm this hypothesis, analyzing biologic mechanism

Rimodellamento osseo perimplantare:background scientifico e implicazioni cliniche

Il nuovo libro dei Dottori Canullo, Cocchetto e Loi è un manuale scritto assieme a più di dieci collaboratori. Il contenuto esamina gli aspetti fondamentali dell'implantologia odontoiatrica per poi passare ai più moderni concetti del platform switching, del carico immediato e della piezochirurgia . Il primo capitolo, corredato da ben 186 referenze bibliografiche, analizza i vari aspetti riguardanti il modellamento ed il rimodellamento dell'osso e i rischi ad esso collegati. I fattori locali e sistemici inerenti al paziente sono identificati e valutati. Sono altresi descritte le tre condizioni che maggiormente influiscono sul rimodellamento dell'osso peri-implantare, vale a dire i fattori chirurgici, sistemici e locali . Il secondo capitolo verte maggiormente sugli aspetti clinici: il disegno del lembo e la stabilità del tessuto peri-implantari sono discussi alla luce dei concetti di biotipo e di ampiezza biologica. Il terzo capitolo introduce il nuovo concetto della preaparazione minimamente invasiva del sito dell'impianto applicando le tecniche piezochirurgiche. I due capitoli successivi sono dedicati al concetto di platform switching, che viene trattato sia da un punto di vista teorico che da un punto di vista pratico. Grande enfasi è posta sulle conseguenze istologiche di questo concetto. Molta attenzione è stata data agli stuid sull'analisi degli elementi finiti (FEA). Questi dovrebbero descrivere gli effetti del platform switching sui livelli marginali ossei attorno agli impianti. Bisogna comunque ricordare che la FEA non può descrivere perfettamente qusto tipo di fenomeni biologici dal momento che l'osso, essendo un tessuto vivente, non segue le regole matematiche applicate alla FEA. Il sesto capitolo è incentrato sugli aspetti protesici dell'implantologia odontoiatrica . Lo schema delle preparazioni, gli aspetti delle finishing lines ed i profili d'emergenza sono presentate in maniera dettagliata e le problematiche a loro collegate sono discusse. Il capitolo successivo è incentrato sul ruolo dei protocolli protesici riguardanti la stabilità peri-implantare. Gli aspetti biologici, tecnici e clinici sono discussi conseguentemente. Molta attenzione è data alla protesizzazione provvisoria ed agli aspetti concernenti il paziente come la pianificazione e la riduzione del fastidio durante la riabilitazione protesica . Infine l'ultimo capitolo si dedica al titanio, in qualità di materiale principe per l'implantologia odontoiatrica. Particolare enfasi è data alla pulizia delle superfici in titanio quale prerequisito per un'ottima funzionalità. Per riassumere, il nuovo libro del Dottor Canullo e dei suoi co-autori fornisce una idea di trattamento di implantologia odontoiatrica che include platform switching ed una precisa assistenza protesica affinchè l'esito raggiunto sia un trattamento ottimale del paziente. Il libro è scritto in maniera chiara e può essere raccomandato a tutti i colleghi di implantologia odontoiatrica.The new book of Dr Canullo, Cocchetto and Loi as an editor is a multi-author textbook with more than 10 contributing authors. The content stretches from basic aspects of implant dentistry all the way to the most modern concepts of platform switching, immediate implant placement and the application of piezo-surgery. A well-documented (186 references) first basic chapter discusses the various aspects and risks affecting bone modeling and remodeling. Patient related systemic and local factors are identified and evaluated. Three conditions that definitely affect peri-implant bone remodeling, namely systemic, local and surgical factors are described. In a more clinical, second chapter, flap design and peri-implant tissue stability are discussed in the light of the concept of the biotype and the biologic width. The third chapter presents the novel concept of minimally invasive implant site preparation applying piezo-surgical techniques. Quite a number of paragraphs in two comprehensive chapters are devoted to the platform switching concept. This is dealt with both from a theoretical as well as a practical point of view. Emphasis is placed on the histological consequences of this concept. A lot of attention, perhaps too much, is given to the studies on finite element analysis (FEA). These are supposed to describe the effects of platform switching on the marginal bone levels around implants. It has to be kept in mind, however, that FEA cannot reflect such biological phenomena owing to the fact that bone as a living tissue does not follow the mathematical rules that are applied with FEA. Chapter six is devoted to the prosthetic aspects of implant dentistry. Design of preparations, aspects of finishing lines and emergence profiles are presented in a comprehensive way and pertinent issues are addressed. The clinical concept of a “shoulderless” abutment is discussed. The chapter is illustrated with a few relevant clinical cases to support single issues. Another chapter presents the role of prosthetic protocols on peri-implant stability. Biological, technical and clinical aspects are discussed in harmony. A lot of attention is given to the temporarisation and to patient-centred aspects such as scheduling and reduction of discomfort during prosthetic rehabilitation. Finally, the last chapter is devoted to titanium as a material of choice for implant dentistry. Emphasis is given to the cleaning of titanium surfaces as a prerequisite for optimal function. In summary, the new book by Luigi Canullo and his co-workers provides a implant dentistry treatment concept that includes platform switching and strict prosthetic guidance to reach optimal treatment outcomes. The book is written in a lucid way and may be recommended to all colleagues who are involved in implant dentistry

Immediate positioning of a definitive abutment versus repeated abutment replacements in post-extractive implants: 3-year follow-up of a randomised multicentre clinical trial

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 (T(0) = implant insertion), final restoration (T(1) = 3 months later), and at 18-month (T(2)) and 3-year (T(3)) 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 T(1), 0.43 mm at T(2), and 0.55 mm at T(3). In the DA group, peri-implant bone resorption was 0.35 mm at T(1), 0.33 mm at T(2), and 0.34 mm at T(3). Statistically significant lower bone losses were found at T(2) (0.1 mm) and T(3) (0.2 mm) for the DA group. At T(3), 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 abutmen-one time' concept might be a possible additional strategy in post-extraction immediately restored platform-switched single implants to further minimise pen-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

Immediate positioning of a definitive abutment versus repeated abutment replacements in post-extractive implants: 3-year follow-up of a randomised multicentre clinical trial

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 ( &lt; 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

Soft and hard tissue response to an implant with a convergent collar in the esthetic area: preliminary report at 18 months

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