Serge Szmukler-Moncler

Purpose: To evaluate interproximal bone stability in cases of inter-implant distance (IID) < 3 mm over a follow-up period of up to 10 years, and to assess the agreement between digital and radiographic methods for measuring implant spacing. Materials and methods: This retrospective cohort study included 18 pairs of adjacent implants, featuring platform-switching and internal conical connection, placed with an IID < 3 mm and followed for a mean period of 7.32 ± 2.31 years. IID was determined using three approaches: periapical radiography with simple internal calibration, a composite radiographic calibration incorporating vertical and horizontal distortion factors of both implants, and a digital three-dimensional workflow based on intraoral scanning and STL superimposition. Peri-implant marginal bone levels and mid-interproximal bone height were evaluated relative to the implant–abutment junction (IAJ) and to a reference line connecting adjacent IAJs, respectively. Agreement between measurement methods was assessed using Bland–Altman analysis and intraclass correlation coefficients; equivalence testing was performed using two one-sided tests (TOST). Associations between IID and bone parameters were explored using Spearman correlation. Results: The mean digitally measured IID was 1.81 ± 0.71 mm, with 55.6% of sites presenting an IID < 2 mm. Peri-implant marginal bone levels were coronal to the IAJ in 88.9% (32/36) of sites. Mid-interproximal bone was located 1.97 ± 0.88 mm coronal to the line connecting adjacent IAJs. No statistically significant association was found between IID and peri-implant or interproximal bone levels. IID measurement methods demonstrated a high agreement of ICC = 0.95; nonetheless, simple radiographic calibration tended to underestimate IID. At an equivalence margin of ± 0.1 mm, only composite calibration was interchangeable with the digital method. Conclusions: Within the limitations of this retrospective cohort, inter-implant distances below 3 mm, with the majority below 2 mm, were not associated with interproximal bone loss after up to 10 years of function. The digital workflow enabled distortion-free assessment of implant spacing and provided a reference for evaluating radiographic calibration methods. The present findings warrant confirmation in prospective studies with larger cohorts.

Purpose: The biological response of dental tissues to implants placed in contact with retained roots is poorly documented. The aim of this report is to describe the histological findings of three implants that inadvertently engaged inflammation-free retained root fragments during placement and were retrieved after 10 and 12 weeks of healing in the pig mandible. Materials and methods: Three implants were retrieved from a preclinical pig model in which fractured root remnants were inadvertently left in situ following tooth extraction; implants were placed after a three-month healing period and were harvested after 10 and 12 weeks. Histological evaluation was carried out using optical microscopy, polarized light microscopy, and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy to characterize the tissue responses at the implant–root interface. Three configurations of implant–root contact were identified: (1) an implant fully embedded within a retained root composed of dentin and osteodentin; (2) an implant presenting apical contact with a retained root; and (3) an implant apex engaging fractured-root debris. Results: The implant fully embedded within the retained root exhibited uninterrupted contact with dentin and osteodentin, with no intervening soft-tissue layer. Areas of tight implant–dentin apposition were devoid of cellular activity; conversely, in regions where microgaps or interfacial space were present, osteodentin showed active modeling and remodeling along the implant surface. In the second and third samples, osseointegration was observed along the implant body in contact with bone despite the presence of apical contact with residual root tissues. Newly formed osteodentin was intimately adapted to the implant apex, whereas the periodontal ligament that persisted did not extend appreciably onto the implant surface. Conclusions: This preclinical report describes the histological response to three implants in contact with non-infected retained roots. In two specimens with partial root contact, bone was present at the interface and osseointegration was observed. In all three specimens, newly formed osteodentin was present at the implant interface, with evidence of early modeling and remodeling. Further controlled investigations are required to confirm these observations and to assess their reproducibility and broader biological relevance.

Background: A minimum interimplant distance (IID) of 3 mm has been recommended to preserve the interproximal bone crest and soft tissue papilla. In immediate full‐arch rehabilitations requiring tilted posterior implants, anatomical constraints may not allow such spacing. When implants are placed in close proximity, conventional angulated multiunit abutments (MUAs) can lead to prosthetic interference and compromised mechanical resistance. This case report describes the management of two tilted implants with an IID <1 mm using a novel eccentric MUA. Implant spacing was precisely quantified using a superimposition‐based digital workflow. Case Presentation: A 72‐year‐old woman underwent extraction and immediate placement of six implants in the maxilla for full‐arch rehabilitation. Two posterior maxillary implants were positioned less than 1 mm apart. This prevented the use of conventional angulated MUAs. An eccentric MUA providing a 3.6 mm horizontal offset enabled restoration of adequate prosthetic spacing. A definitive prosthesis with a titanium laser‐welded framework and composite veneering was fabricated and delivered 24 h after surgery. At the 6‐year follow‐up, no biological or major mechanical complications were observed. In the narrow interimplant area, bone extended above both implant necks and the papilla persisted. After unscrewing the prosthesis, digital intraoral scanning with scan bodies and STL superimposition allowed digital measurements of the IID. Conclusions: This 6‐year case report documents the use of a noncustomized eccentric MUA with a 3.6 mm offset as a practical solution for managing an IID <1 mm. This was achieved without compromising prosthetic function or papilla formation. The crestal bone between the close implants appeared to remain stable over the follow‐up period. It is speculated that it may be related to the platform‐switching design and stability of the internal conical connection. Further clinical studies are warranted to assess the biomechanical reliability of eccentric abutments and the long‐term behavior of interimplant crestal bone when spacing is <1 mm.

Background: Dental implant systems provide standard cylindrical healing abutments of various diameters; however, they do not match the larger shape of the complex emergence profile of the prosthetic crowns. Adaptation of the soft tissues from a circular emergence profile to the one that suits the prosthetic crown involves a simultaneous squeezing and stretching of the gingiva. Often, this translates into local blanching of the gingiva and the prosthodontist must assess that blanching is transient. There is no literature about how much strain exerted by the prosthetic crown is leading or not to gingiva blanching. Aim of this paper is to present a digital workflow that allows measuring, upon prosthesis delivery, how much the strained gingiva is displaced under the crown and leads or not to blanching of the peri-implant soft tissues. Method and Results: The digital workflow involves 3 intra-oral scans (IOS), IOS#1 at completion of the soft tissue healing, IOS#2 at prosthesis delivery, IOS#3 after soft tissue conditioning, and the STL files of the healing cap, the abutment, the implant and the prosthetic crown. The above are superposed and merged following a dedicated protocol that provides access to the distance the delivered crown deforms the strained gingiva. The present case study displayed distinct blanching intensities. Severe blanching was present when the strains applied to the gingiva caused a displacement of 1.3 mm and above; a displacement of 0.9 mm led to moderate blanching. No blanching was observed up to a displacement of 0.6 mm. Conclusion: A digital protocol, involving the superposition and merging of IOSs taken along a defined timeline and STLs of the implant hardware, allowed measuring the displacement distances a prosthetic crown wields upon delivery on the gingiva beneath the prosthesis. Various intensities of gingiva blanching could be related to distinct displacement distances of the healed gingiva that were triggered by attaching a prosthetic crown to the implant neck.

Peri-implantitis is a steadily rising disease and is caused by oral bacterial pathogens able to form biofilm on implant surfaces and peri-implant tissues, making antibiotics treatment less effective. The use of commercial probiotics against oral pathogens could serve as an alternative to prevent biofilm formation. Streptococcus intermedius is one of the early colonizers of biofilm formation in dental implants. The aim of this study was to model the interaction between S. intermedius and Streptococcus salivarius strain K12, a probiotic bacterium producing bacteriocins. S. intermedius was co-cultured with S. salivarius K12 in an in vitro model simulating the biofilm formation in a dental implant composed by a titanium cylinder system. Biofilm formation rate was assessed by Real-Time PCR quantification of bacterial count and expression levels of luxS gene, used in response to cell density in the biofilm. Biofilm formation, bacteriocin production, luxS expression patterns were found to be already expressed within the first 12 h. More importantly, S. salivarius K12 was able to counter the biofilm formation in a titanium cylinder under the tested condition. In conclusion, our dental implant model may be useful for exploring probiotic-pathogen interaction to find an alternative to antibiotics for peri-implantitis treatment.

Our purpose was to physically characterize the surface, and the subsurface, of a macro- and micro-textured titanium grade 5 dental implant surface obtained by etching only, without sandblasting. The topography, surface roughness, as well as the surface structure and subsurface distribution of elements, were determined by scanning electronic microscopy (SEM), non-contact profilometry, X-ray diffraction (XRD), and a concentration profile performed by Auger electron spectroscopy (AES). The hydrogen concentration in the implants was measured; the ability to generate nanostructures when stored in deionized water was also investigated. Under SEM, the surface resembled a sandblasted and etched titanium surface with its typical macro- and micro-texture; roughness was moderate with average roughness (Sa) 1.29 µm. No titanium hydride was found at the implant surface and no enrichment of any alloying element was identified at the surface and subsurface. Hydrogen concentration was 79 ppm, within the normative tolerance (<130 ppm). After storage in water for 6 months, densely packed finger-like nanostructures were observed. The clinical advantage of this textured titanium alloy surface is that it displays the typical macro- and micro-features of a moderately rough sandblasted and etched (SLA) titanium surface without leaving behind any foreign sandblasting material.

Background: When a residual root is found in the way of a planned implant placement, invasive surgery is usually performed in order to remove it. Consequently, implant therapy is rendered more complex and lengthy.Purpose: We present 6 cases treated according to an unconventional protocol in which invasive surgery was avoided by allowing the implants to encroach upon the residual roots in order to permit a prosthetically driven surgery.Materials and Methods: Six patients were treated with 7 implants placed through a residual root (4 in the mandible and 3 in the maxilla). The residual roots had to be clinically and radiographically asymptomatic and covered by bone or healthy gingiva. The radiographic follow‐up ranged from 20 months to 9 years.Results: Healing was uneventful. Implants were clinically stable, and radiographic examination did not show any unusual feature at the root‐implant interface.Conclusion: Several types of new implant‐tissue interfaces were created in addition to the classical implant‐bone interface, but this did not seem to jeopardize implant integration. Reports of more cases with a longer follow‐up are needed before this protocol can be endorsed for routine application. Nonetheless, if confirmed as acceptable, this protocol might open intriguing possibilities; it might also lead to revision of one of the leading concepts in dental implantology.

Objectives: Acid etching is a popular method to texture the surface of dental implants. During etching, the titanium oxide protective layer is dissolved and small native hydrogen ions diffuse into the unprotected implant surface. They enrich the implant surface with hydrogen and precipitate into titanium hydride (TiH). The aim of this study was to measure the concentration of TiH at the implant surface and the total concentration of Hydrogen at five commercially available implant systems, made of either commercially pure (cp) titanium or titanium alloy.Material and methods: X‐Ray diffraction (XRD) was conducted on each implant system to determine the compounds present at the implant surface. Following a TiH₂/Ti calibration curve, the concentration of TiH was determined. Concentration of hydrogen in the implants was measured by the inert gas fusion thermal conductivity/infrared detection method.Results: XRD data showed that TiH was present on all cp titanium implants but not on the alloyed implants. TiH concentration varied between 5% and 37%. Hydrogen concentration varied between 43 and 108 ppm, no difference in uptake was found between the cp titanium and alloyed implants. Low solubility of hydrogen in α‐titanium is responsible for precipitation into TiH. Stronger etching conditions led to higher concentration of TiH2‐x.Conclusion: High solubility of hydrogen in the β‐phase of the alloy is preventing hydrogen from precipitating into TiH. All implants, even those lacking TiH at the surface, were enriched with hydrogen. In all implants, hydrogen concentration was within the normative limit of 130 ppm. To cite this article: Szmukler‐Moncler S, Bischof M, Nedir R, Ermrich M. Titanium hydride and hydrogen concentration in acid‐etched commercially pure titanium and titanium alloy implants: a comparative analysis of five implant systems. Clin. Oral Impl. Res. 21, 2010; 944–950. doi: 10.1111/j.1600‐0501.2009.01938.x

Surface texturing by acid etching has recently become popular among dental implant manufacturers. The aim of this study was to compare the surface topography of four implant systems and to check the reproducibility of the industrial process of each implant system. Three implants per system have been selected from three distinct batches. They were observed under a scanning electron microscope (SEM), and roughness was determined with a contact profilometer by measuring five height‐descriptive parameters (Ra, Rq, Rz_ISO, Rt, and Rsk, a texture parameter Sm, and a hybrid parameter RΔq. The analysis showed that each implant system displayed a distinct surface topography that could not be mistaken. When sandblasting was performed prior to etching, surface topography was a combination of macro‐ and microroughness. The roughness and the amount of remaining sand varied among the batches, showing that the industrial process is not fully developed. Deviation from the released technical information was found for two out of four implant manufacturers. Based on the available biological and clinical data on textured surfaces, it is suggested that it is bone interlocking at the interface that maintains the biological properties of textured surfaces, rather than a strong implant fixation per se. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 46–57, 2004

The SLA (sandblasted with large grit and acid etched) surface is a textured surface that has been documented to lead to a rapid and strong implant fixation. The purpose of the present study was to determine the contribution of sandblasting in addition to etching to implant anchorage. It was also aimed to determine if the pits carved during etching alone have a bone‐interlocking capacity that leads to microanchorage between the implant and bone. SLA implants and machined‐and‐acid‐etched (MA) implants were placed in the maxilla of Land Race pigs. After 10 weeks of healing, they were reverse torqued. The reverse torque of the SLA and MA implants was 157.29 ± 38.04 N cm and 105.33 ± 25.12 N cm, respectively. Sandblasting increased bone anchorage by 49.3%; the difference was statistically significant (p = .028). Bone was found attached to both surfaces; bone ingrowth was found in the pits of both surfaces. It is suggested that the two surfaces are able to generate bone interlocking and mechanical coupling at the interface. When finite‐element modeling is performed with these surfaces, it is suggested that the bound mode be used instead of the slip mode. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 68B: 149–159, 2004