Search

For decades, the histologic evidence about osseointegration and the bone-implant interface has been discussed in the literature. In this review, the effectiveness of dental implants retrieved for different causes was evaluated. A literature search was performed in databases for papers about implants retrieved from humans published by the Implant Retrieval Center of the University of Chieti-Pescara, Italy. Sixty-eight articles were selected into categories based on topics. The data indicated high level of bone-to-implant contact, lamellar bone close to the surface, roughness related to an increased bone response, organized and remodeled bone after loading, and peri-implant interfaces subjected to a continuous dynamic function.

This report describes the restoration of the healed single implant in the posterior region by using a lithium disilicate crown supported by an Acuris abutment. The restored implants were placed in the premolar and molar region of both the mandible and the maxilla by using a 1-stage approach. The definitive Acuris abutment was placed after an implant healing period of at least 3 months. Definitive impressions were made at least 3 months after surgery. The precrystallized lithium disilicate crown was adapted to a laboratory abutment and evaluated. The crown was then crystallized, finished, colored, and cemented to the definitive abutment by using an adhesive resin cement. The definitive restoration engaged the abutment without the use of screws or cement. A single healed implant can be successfully restored by using a lithium disilicate restoration supported by an Acuris abutment.

Background: In more than three decades of work of the Retrieval Bank of the Laboratory for Undemineralized Hard Tissue Histology of the University of Chieti-Pescara in Italy, many types of biomaterials were received and evaluated. The present retrospective review aimed to evaluate the histological and biological aspects of the evaluated bone substitute biomaterials. Methods: In the present study, the authors prepared a retrospective analysis after the screening of some databases (PubMed, Scopus, and EMBASE) to find papers published from the Retrieval Bank of the Laboratory for Undermineralized Hard Tissue Histology of the University of Chieti-Pescara analyzing only the papers dealing with bone substitute biomaterials and scaffolds, in the form of granules and block grafts, for bone regeneration procedures. Results: Fifty-two articles were found, including in vitro, in vivo, and clinical studies of different biomaterials. These articles were evaluated and organized in tables for a better understanding. Conclusions: Over three decades of studies have made it possible to assess the quality of many bone substitute biomaterials, helping to improve the physicochemical and biological properties of the biomaterials used in daily clinical practice.

To provide a 1-year assessment of friction-retention abutments (Acuris, Dentsply Sirona) used to retain a single lithium disilicate (LSA total of 522 implants were placed to treat single-tooth premolar and molar edentulous sites in the mandible or maxilla. Three types of implants were used. The tested abutments were connected 3 months after implant placement. A single pressed LSA total of 507 patients (284 women and 223 men) received a restoration (T0), and 504 of them reached the T2 1-year follow-up. One restoration fractured after 10 months in function. No statistically significant difference was assessed in the soft tissue measurements or in the measurements of the distance between the supporting implant platform and the bone peak. None of the restorations detached during the observation period.The friction retention abutment is a viable option to retain an implant-supported monolithic LS

In guided surgery, implants can be planned from radiographic guide information according to a restoratively driven treatment plan. Unfortunately, the palatal or lingual surface of teeth cannot be easily identified. The present article describes the use of a digitally designed prosthetic shell to improve the accuracy of guided-welded approach planning for immediate restorations supported by conometric abutments. Importing the virtual shell into the planning software provides an effective protocol for using the definitive prosthetic space information to plan the framework shape and position predictably. This method increases the accuracy of virtual planning and reduces the time needed to reline the prosthetic shell.

Purpose To evaluate the 2-year performance of definitive implant- or tooth-supported three-unit fixed dental prostheses made of zirconia-reinforced lithium silicate placed to restore premolars and molars in clinical cases of partial edentulism. Materials and methods All patients received a three-unit fixed restoration made of monolithic, hot-pressed, zirconia-reinforced lithium silicate glass-ceramic. The restoration was cemented to two natural teeth or attached to two 3.5- or 4.5-mm-diameter square threaded, grit-blasted, acid-etched integrated implants with a Morse taper connection. Peri-implant pocket depth and bone and soft tissue remodeling were recorded for 2 years at each follow-up visit. Esthetic, functional, and biologic United States Public Health Services (USPHS) parameters modified by the World Dental Federation study design were assessed yearly until the final follow-up appointment. At the time of placement of the definitive restorations and at the 2-year follow-up visit, the opposing dentitions were identified by type of restoration and supporting structures. Results A total of 100 patients were consecutively enrolled in the period between June 2016 and July 2017, and 50 patients each received an implant-supported restoration (Group A) or a tooth-supported restoration (Group B). One (2%) of the 50 implant-supported prostheses fractured after 21 months of function. None of the other prostheses failed or became loose or detached. No significant differences involving probing levels or bone and soft tissue remodeling were found between the follow-up times. No cases of inflammation or infection of the mucosal cuff around the neck of the implants were recorded. The most common issue occurred immediately after placement of the prosthesis, when 3 patients (6%) from Group A and 4 patients (8%) from Group B asked for a modification of tooth shade. Conclusion Implant-supported or tooth-supported three-unit fixed dental prostheses made of zirconia-reinforced lithium silicate can be used to successfully restore cases of posterior partial edentulism. The 2-year results of this report will be studied more in depth in ongoing long-term research.

The goal of this case series was to evaluate the clinical outcome at the 2-year follow-up of immediately loaded combined screw- and conometric-retained implant-supported full-arch restorations virtually planned using digital scanning technology.This series included 12 patients presenting hopeless teeth in the maxilla treated with computer-guided flapless implant placement. A total of 72 implants were inserted. All implants were immediately loaded with a complete-arch restoration supported by an intraorally welded framework. Digital scanning technology was used to virtually plan a combined screw and conometric retention of the frameworks. Clinical parameters were assessed at 1 week and at 1, 3, 6, 12, and 24 months follow-up.The survival rate after 2 years was 98.6%, as one implant failed during the osseointegration period. No major prosthetic complications were observed such as issues with mobility, unscrewed abutments, disconnected conometric copings, and prosthetic fracture. Only one patient registered the chipping of a prosthesis.Based on the results of the present study, the use of combined screw and conometric retention for fixed immediate restorations properly planned using digital scanning technology seems to be a viable treatment alternative to screw or conometric retention alone for immediately loaded rehabilitations.

Background: The aim of the present review was to assess the histological and histomorphometrical data from the paper published by our Laboratory on peri-implant bone in dental implants in different loading conditions. Methods: The papers published in different implant loading conditions, in dental implants retrieved from humans, and in the Hard Tissues Research Center of the University of Chieti-Pescara, Italy, were screened on MEDLINE/PubMed, Embase, Scopus, and other electronic databases until 31 December 2018. Only articles that reported the histological and histomorphometrical values of the Bone-Implant Contact (BIC) were selected. Results: The system selection provided a total of 155 papers. The manuscripts included for the narrative review were 57. These papers provided histological and histomorphometrical data. Conclusions: The bone remodeling around dental implants was found to be a dynamic process; loading changed the microstructure of the peri-implant bone; and implants were found to provide a successful function, over several decades, with different range of degrees of BIC in vivo (varying from a little more than 30% to a little more than 90%). Loaded implants presented a 10%−12% higher BIC values when compared to submerged, unloaded implants, and rougher surfaces had, on average, about a 10% higher BIC than machined surfaces.

Purpose To evaluate the performance of definitive, implant-supported, lithium disilicate fixed dental prostheses (LS2 FDPs) manufactured with a computer-assisted design/computer-assisted manufacturing (CAD/CAM) system. All patients received two-unit restorations placed in posterior regions, supported by osseointegrated implants with cone-in-cone connection abutments. Materials and methods Two implants (Ankylos) were placed into healed sites or fresh extraction sockets in the maxillary/mandibular posterior regions of partially edentulous patients. Definitive digital impressions were made 3 months after surgery. Twenty-four patients received fixed monolithic LS2 restorations manufactured with the CEREC system. All restorations were connected to the implants using cone-in-cone connection abutments. Peri-implant pocket depths were recorded for 2 years at each follow-up visit. Esthetic, functional, and biologic United States Public Health Services (USPHS) parameters modified by the FDI World Dental Federation study design were assessed yearly until the last follow-up appointment. The opposing dentitions were identified by type of restoration and supporting structures at the time of placement of the definitive restorations and at the 2-year follow-up visits. Results One patient (4.16%) moved to an unknown location during the study. A total of 23 FDPs (95.8%) supported by 46 implants reached the 2-year follow-up. None of the prostheses failed, or became loose or detached. No significant difference involving probing levels between the experimental times were found. Conclusions The results of this research indicated that the abutment-prostheses connection using a cone-in-cone approach was successful within the 2-year period of this study. None of the studied monolithic LS2 glass-ceramic prostheses milled using the CEREC CAD/CAM system fractured or became detached.

Symmetric and well-organized connective tissues around the longitudinal implant axis were hypothesized to decrease early bone resorption by reducing inflammatory cell infiltration. Previous studies that referred to the connective tissue around implant and abutments were based on two-dimensional investigations, however, only advanced three-dimensional characterizations could evidence the organization of connective tissue microarchitecture in the attempt of finding new strategies to reduce inflammatory cell infiltration. We retrieved three implants with a cone morse implant–abutment connection from patients, they were investigated by high-resolution X-ray phase-contrast microtomography, cross-linking the obtained information with histologic results. We observed transverse and longitudinal orientated collagen bundles intertwining with each other. In the longitudinal planes, it was observed that the closer the fiber bundles were to the implant, the more symmetric and regular their course was. The transverse bundles of collagen fibers were observed as semicircular, intersecting in the lamina propria of the mucosa and ending in the oral epithelium. No collagen fibers were found radial to the implant surface. This intertwining three-dimensional pattern seems to favor the stabilization of the soft tissues around the implants, preventing inflammatory cell apical migration and, consequently, preventing bone resorption and implant failure. This fact, according to the authors’ best knowledge, has never been reported in the literature and might be due to the physical forces acting on fibroblasts and on the collagen produced by the fibroblasts themselves, in areas close to the implant and to the symmetric geometry of the implant itself.

Purpose: The aims of this study were to evaluate the ability of a stepped osteotomy to improve dental implant primary stability in low-density bone sites and to investigate possible correlations between primary stability parameters. Materials and Methods: The study was performed on fresh humid bovine bone classified as type III. The test group consisted of 30 Astra Tech EV implants inserted following the protocol provided by the manufacturer. The first control group consisted of 30 Astra Tech EV implants inserted in sites without the underpreparation of the apical portion. The second control group consisted of 30 Astra Tech TX implants inserted following the protocol provided by the manufacturer. Implant insertion was performed at the predetermined 30 rpm. The insertion torque data were recorded and exported as a curve; using a trapezoidal integration technique, the area underlying the curve was calculated: this area represents the variable torque work (VTW). Peak insertion torque (pIT) and resonance frequency analysis (RFA) were also recorded. Results: A Mann-Whitney test showed that the mean VTW was significantly higher in the test group compared with the first control and second control groups; furthermore, statistical analysis showed that pIT also was significantly higher in the test group compared with the first and second control groups. Analyzing RFA values, only the difference between the test group and second control group showed statistical significance. Pearson correlation analysis showed a very strong positive correlation between pIT and VTW values in all groups; furthermore, it showed a positive correlation between pIT and RFA values and between VTW and RFA values only in the test group. Conclusion: Within the limitations of an in vitro study, the results show that stepped osteotomy can be a viable method to improve implant primary stability in low-density bone sites, and that, when a traditional osteotomy method is performed, RFA presents no correlation with pIT and VTW.

The only way to evaluate the short- and long-term response of human bone tissue to the insertion of dental implants and to corroborate the results of in vitro and of animal experimental studies is to study well-integrated human-retrieved dental implants, with surrounding human bone tissue, possibly after different time periods after the insertion in the bone. Several papers report that moderately rough implant surfaces are, probably, the best in terms of mineralized tissues response at the bone-implant interface. Results from our Laboratory, in a span of 30 years, have found that immediate loading did not create adverse effects regarding the formation of mineralized tissues at the interface with dental implants and has, probably, a beneficial effect on the peri-implant bone response, producing changes in the peri-implant bone microstructure. Osseointegration is a very dynamic ongoing process with the peri-implant bone tending to become more organized over the years; these higher degrees of organization are reflected by the large quantity of remodeling areas in the mature, lamellar bone, indication of multiple remodeling cycles over the years of loading. Bone remodeling is a prerequisite for dental implants to support functional loading in the long term, and remodeling, very well-organized, mineralized, lamellar bone is found at the interface of retrieved implants even after three decades of loading. Bone-implant contact (BIC) and bone mechanical properties were found to increase over time, and the bone tissue adapted to loading conditions to increase its biomechanics. In the specimens evaluated in our Laboratory, high percentages of bone-implant contact was found in all well-integrated retrieved implants, with the presence of mineralized, mature, lamellar bone in close contact with the metal surface, around all the implant perimeter, with no epithelium migration downward or presence of fibrous, connective tissue. In the specimens evaluated in our Laboratory over several decades, the bone-implant contact percentage was found to vary from 32 to 37% to more than 90–95%. These results point to the fact that dental implants could function with different percentages of mineralized tissues at the interface, and even implants with a low bone-implant contact percentage were stable, well-integrated, and able to bear loading conditions over the years. Mineralized bone was absent at the base of the threads in unloaded implants, and, at the tip of the threads in loaded implants, osteocytes (the mechanosensors in bone) were always found in the peri-implant bone, with a significantly higher number in loaded implants than in unloaded implants. Loaded implants presented a significantly higher number and thickness of bone trabeculae.

Purpose This study evaluated the retention strength of welding caps for Ankylos standard abutments using a pull-out test. Materials and methods Each sample consisted of an implant abutment and its welding cap. The tests were performed with a Zwick Roell testing machine with a 1-kN load cell. Results The retention strength of the welding caps increased with higher abutment diameters and higher head heights and was comparable or superior to the values reported in the literature for the temporary cements used in implant dentistry. Conclusion Welding caps provide a reliable connection between an abutment and a fixed prosthesis without the use of cement.

Objectives The aims of the present cross-sectional study are to evaluate the bone remodeling around Morse-cone implants placed subcrestally 1 year after loading and the prevalence of bone loss >0.5 mm after at least 3 years of loading. Material and methods Subjects who underwent a radiographic check in 2013 with implants that had been in function for at least 3 years were considered for inclusion. The study population comprised of 145 subjects with a total of 523 implants. At the moment of insertion, all the implants were placed subcrestally from 1 to 3 mm as clinically measured. Radiographs taken at baseline, that is 1 year after loading (T0), and at the follow-up visit in 2013 (T1) were examined. The distance between the rim of the implant and the marginal bone level at mesial and distal aspects of each implant was determined and the mean bone loss calculated. Results In the total sample, the mean bone loss occurred between baseline and 2013 examination was 0.42 ± 0.77 mm; at T1 424 implants presented the marginal bone level at the implant rim (78) or above it (346). On the other hand, 99 implants presented the rim above the bone crest. Fifty-one implants that at T1 presented the rim above the bone crest, and that between T0 and T1 had lost at least 0.5 mm, were considered losers: 10 implants lost up to 0.5 mm, 11 lost from 0.6 to 1 mm, 16 lost from 1.1 to 2 mm, and 14 lost more than 2 mm of bone. On a subject basis, 34 subjects (group A) with a total of 200 implant sites presented loser implants, while 111 subjects (group B) with 323 implants displayed non-loser implants. Conclusions Within the limits of a cross-sectional study, the results show that Morse-cone implants placed subcrestally in the vast majority of cases (89.9%) are able to maintain the bone crest at level of the rim or above it 1 year after loading. The incidence of loser sites (bone loss >0.5 mm) after at least 3 years of follow-up is 9.7% at implant level and 23.5% at patient level.

This study aimed at a histologic and histomorphometric analysis of the periimplant tissues and bone-titanium interface reactions in successfully osseointegrated, clinically stable, and immobile human titanium dental implants retrieved after a long loading period.In the last 30 months (2013-2015), 21 implants, retrieved from individuals for different causes after a loading period ranging from 4 to 20 years, were sent to the Implant Retrieval Center, University of Chieti-Pescara, Italy. In 4 cases, almost all the bone had been lost during the retrieval, whereas in the remaining 17 cases, mineralized bone was still present.Around the majority of the implants, mature compact bone with few marrow spaces was found. The trabecular bone, constituted by a few thin bone trabeculae, was in a periimplant location around only a few implants. A high percentage of bone-implant contact (BIC) (comprised between 32 ± 4.1% and 83 ± 2.9%) was present. In almost all implants, the space within the threads was almost completely filled by compact lamellar bone or by a thin layer of bone. Close and tight contact between bone and implant surface was observed in all specimens with no gaps or connective tissue at the interface.All implants appeared to be well integrated in the surrounding mineralized bone, and all of them showed adequate bone-to-implant contact percentages.

The use of the cone-in-cone connection to support definitive restorations was previously evaluated in cases involving full-acrylic resin or hybrid acrylic-resin composite prostheses. The aim of this study was to evaluate the performance of definitive fixed partial prostheses made with monolithic zirconia and supported by cone-in-cone abutments and integrated implants. Implants were placed into healed sites and fresh extraction sockets. The prostheses were placed in the posterior regions of partially edentulous patients after healing periods of 3 months. A total of 76 patients received fixed monolithic zirconia restorations splinted with cone-in-cone connections to two implants that were followed up yearly for 5 years. At each follow-up visit, peri-implant bone levels and pocket depths were recorded. Esthetic, functional, and biologic United States Public Health Services parameters modified by the World Dental Federation study design were assessed at the last follow-up appointments. The opposing dentition was categorized by type of restoration and supporting structure at the time of placement of the definitive zirconia partial restoration and at the 5-year follow-up. The treatment achieved an 88.2% success rate and a 97.4% survival rate at the 5-year follow-up. None of the prostheses became loose or detached. One fixed prosthesis (0.76%) fractured 41 months after placement. No significant difference involving peri-implant bone and probing levels between the experimental times was found. The results of this research indicated that abutment-prosthesis cone-in-cone connections were successful within the 5-year study period.

The aim of this study was to analyze the degree of mineralization around nine clinically stable titanium dental implants retrieved after 2 months to 17 years for mechanical complications from five patients. The micromorphology and microchemistry of the interface bone at the coronal and apical sides of the threads were analyzed by environmental scanning electron microscope and energy-dispersive X-ray spectroscopy (EDX) on histologic samples. Mineralization was investigated by atomic calcium-to-nitrogen (Ca/N), phosphorous-to-nitrogen (P/N), and calcium-to-phosphorous (Ca/P) ratio evaluation (statistical analysis by two-way analysis of variance with Student-Newman-Keuls; P < .05). EDX showed higher Ca/N, P/N, and Ca/P values for the bone at the coronal side compared to the apical side of the threads in the long-term (≥ 14 years) samples. The two most significant findings were that (1) the interface bone located at the coronal side of the implant threads was generally more mineralized than the interface bone located at the apical side, and (2) the mineralization of the peri-implant bone at the interface increased over time. A higher degree of mineralization was found at 2 months in an immediately loaded implant when compared to the 2-month submerged unloaded control, likely related to the different remodeling events (coronal vs apical side of the implant threads) due to the direction of the loading forces.

Inaccuracy of computer-guided implant placement may lead to complications when combined with an immediately loaded prefabricated prosthesis. The aim of this case series was to describe the use of an intraoral welding technique to increase the predictability of immediately loaded implants supporting a fixed full-arch prosthesis after computer-guided flapless implant placement. A total of 60 Ankylos plus implants (Dentsply) with a width of 3.5 mm and a length of 8 to 14 mm were placed consecutively in 10 patients. The implants were functionally loaded using the intraoral welding technique on the day of surgery. The accuracy of guided implant placement was assessed by matching the planning cone beam computed tomography (CBCT) scans with postoperative CBCT scans. No mechanical or biologic complications were registered at the 1-year follow-up. The global coronal deviation of implant placement from the guide plan ranged from 0.25 to 2.84 mm (SD: 0.6 mm), with a mean of 1.28 mm. Average angle deviation was 3.42 degrees (range 0.38-7.82 degrees; SD: 1.52 degrees). The global apical deviation ranged between 0.36 and 3.85 mm (SD: 0.71 mm), with a mean of 1.65 mm. Despite the inaccuracy registered, this guided-welded approach allowed successful achievement of a passive fit of the full-arch prosthesis on the inserted implants the same day of the surgery and provided a high implant and prosthetic survival rate at the 1-year follow-up.

Conometric retention has recently been proposed as an alternative to cemented or screwed retentions for fixed restorations. Conometric copings can only compensate for slightly nonparallel placement without interfering with retention. This article describes a method of using digital scanning technology to facilitate computer-guided implant planning when an immediate restoration supported by conical abutments is planned with a guided-welded approach. The procedure involves importing the scan data of the conometric coping and of the definitive cast obtained from the surgical template into the implant planning software. This approach increases the accuracy of computer-guided implant planning and reduces the time needed for the surgery.

Various grafts or combination of bone substitute materials have been used in sinus lift procedures. Currently, ongoing developments in several disciplines, from molecular biology and chemistry to computer science and engineering, have contributed to the understanding of biological processes leading to bone healing after the use of bone substitute materials (BSBs) and therefore of the behavior of BSBs. The understanding of the properties of each graft enables individual treatment concepts and therefore allows shift from a simple replacement material to the modern concept of an individually created composite biomaterial. Indeed, the choice of the best BSB still remains crucial for success in maxillary sinus augmentation procedures. The present article provides an overview of most of the materials currently available for sinus lift, with a specific focus on their histological, molecular, cellular and pharmaceutical aspects.

Fatigue behavior of the titanium bars is of utmost importance for the safe and reliable operation of dental implants and prosthetic constructions based on these implants. To date, however, only few data are available on the fatigue strength of dental prostheses made with electric resistance welding and laser welding techniques. This in-vitro study highlighted that although the joints made with the laser welding approach are credited of a superior tensile strength, joints made with electric resistance welding exhibited double the minimum fatigue strength with respect to the joints made with laser welding (120 vs 60 N).

The aim of this study was to histologically and histomorphometrically analyze the peri-implant tissue reactions and the bone-titanium interface in loaded Ankylos implants retrieved after loading periods of longer than 1 year. The archives of the Implant Retrieval Center of the Dental School of the University of Chieti- Pescara were searched for Ankylos implants retrieved from humans after a loading period of longer than 1 year. A total of four implants were found: one had been retrieved after 3 years (Friadent plus surface), two after 3.5 years (Friadent plus surface), and one after 10 years (Deep Profile surface). All implants had been loaded; two had been loaded immediately. One implant was retrieved after fracture, one was retrieved after fracture of the superstructure, and the other two were retrieved because of bone resorption with or without infection. Compact bone with few small marrow spaces was present around the three implants retrieved after 3 and 3.5 years; trabecular bone was present around the implant retrieved after 10 years. The bone-implant contact of the three best threads was 35% for the implant retrieved after 10 years, 99% for the implant retrieved after 3 years, and 100% for the implants retrieved after 3.5 years. No untoward effects were present at the interface, and a high bone-implant contact was present around the implants with the microstructured surface. The data show that these implants had the potential to maintain osseointegration under long-term function with continuous and ongoing bone remodeling.

Angiogenesis plays a key role in bone formation and maintenance. Bone formation has been reported to initiate in the concavities rather than the convexities in a hydroxyapatite substratum and the implant threads of dental implants. The aim of the present study was to evaluate the number of the blood vessels inside the concavities and around the convexities of the threads of implants in a rabbit tibia model. A total of 32 thread-shaped implants blasted with apatitic calcium phosphate (TCP/HA blend) (Resorbable Blast Texturing, RBT) (Maestro, BioHorizons(®), Birmingham, AL, USA) were inserted in 8 rabbits. Each rabbit received 4 implants, 2 in the right and 2 in left tibia. Implants were retrieved after 1, 2, 4, and 8 weeks and treated to obtain thin ground sections. Statistically significant differences were found in the number of vessels that had formed in the concavities rather than the convexities of the implants after 1 (p = 0.000), and 2 weeks (p = 0.000), whilst no significant differences after 4 (p = 0.546) and 8 weeks (p = 0.275) were detected. The present results supported the hypothesis that blood vessel formation was stimulated by the presence of the concavities, which may provide a suitable environment in which mechanical forces, concentrations and gradients of chemotactic molecules and blood clot retention may all drive vascular and bone cell migration.

Purpose The present study aimed to assess clinical and biological performances of several bone substitute biomaterials (BSBs). Materials and Methods The evaluation was conducted at 6 months and after several years on 295 patients undergoing sinus augmentation with 13 different BSBs; the data belonging to previously published studies have been analyzed using innovative mathematical models to evaluate the bone regenerative index (Br) and the structural density index (Ds). Results After 6 months, compared to the Ds index of native bone, the regenerated bone showed a D3 bone type; while, after several years, the regenerated bone type was D2, with an evident increase in the density of the regenerated bone over time. Moreover, the values of Br were higher for combined biomaterials indicating a fewer amount of residual particles and marrow spaces, while the values of Ds were higher for anorganic bovine bone indicating a greater new bone formation and a lesser amount of marrow spaces. After 20 years, the bone regenerated using hydroxyapatite still had a D4 bone quality. Conclusions After 6 months of healing, the regenerated bone had a composite structure resembling poor D3 bone type, and covered approximately one-third of the space filled by BSBs. None of the evaluated biomaterials seemed to be ideal.

Analysis of human-retrieved implants provides a unique opportunity to evaluate osseointegration processes. There is evidence that faster bone apposition is present at textured surfaces, with a very high success percentage. Aim of the present retrospective analysis was an evaluation of 14 human retrieved from humans implants with a wettable, highly hydrophilic, microstructured surface.The archives of the Implant Retrieval Center of the Dental School, University of Chieti-Pescara, Italy, were searched, and a total of 14 implants FRIADENT plus surface (Dentsply Implants Manufacturing GmbH, Mannheim, Germany) retrieved after a loading period comprised between 4 and 8 weeks were found.Around all implants, newly formed bone was found in direct contact with the implant surface, with no connective fibrous tissue found at the interface. In all implants, no epithelial downgrowth was present. A very high bone-to-implant contact percentage was found.The efficacy of dental implants is related to biological and biomechanical stability and to the integration between the bone and the implant. This integration plays the key role in the fixation and anchoring of the implants.

Purpose The aim of this trial was to assess if the nonremoval of abutments placed at the time of surgery would improve bone and gingival healing around single immediately restored implants placed in postextraction sockets. Materials and Methods All patients received a single square-threaded tapered implant placed in postextraction sockets and immediately restored. All the implants were placed 2.0 mm below the bone crest, avoiding any contact with the coronal portion of the buccal wall. Six months after surgery, 35 patients were treated following the control standard prosthetic protocol: the abutments were removed and impressions were made directly on the implant platform. Thirty-three patients underwent the “one abutment at one time” test protocol: impressions were made of the abutments using snap-on abutment copies. The dimensional changes of the soft and hard tissues were assessed using digital photography and cone beam computed tomography radiographs immediately after surgery and at 6-, 12-, and 24-month follow-up examinations. Results All implants were osseointegrated and clinically stable at the follow-up examinations. No statistically significant difference was evidenced between the two groups regarding the measurement of vertical bone healing. After the placement of the final restoration, a significant horizontal loss in the hard tissue portion over the implant platform was assessed (p = .03 mesial sites; p = .04 distal sites). An 87% increase of the mean recession of the buccal soft tissue was observed in the control group (+0.27 mm) in the same time frame. Conclusions The nonremoval of abutments placed at the time of the surgery improves the stability of healed soft and hard tissues around the immediately restored, subcrestally placed tapered single maxillary implant.

Purpose The surface chemical and physical properties of materials used for implants have a major influence on blood clot organization. This study aims to evaluate the blood clot extension (bce) on zirconia and titanium. bce was measured in association to surface roughness (Ra) and static contact angle (θ). Materials and Methods Forty disk-shaped samples of sandblasted yttria tetragonal zirconia polycrystal (sb-YTZP), machined titanium (m-Ti), and sandblasted, high-temperature, acid-etched titanium (p-Ti) were used in the present study. About 0.2 mL of human blood, immediately dropped onto the specimen's surface and left in contact for 5 minutes at room temperature, was used to measure the bce. Specimens were observed under confocal scanning laser and scanning electron microscopes. Results The bce (mean × 107 ± standard deviation [SD] × 106 μm2) was 2.97 ± 6.68 for m-Ti, 5.64 ± 6.83 for p-Ti, and 3.61 ± 7.67 for sb-YTZP. p-Ti samples showed a significantly higher bce. Ra (mean ± SD [μm]) was 0.56 ± 0.7 for m-Ti, 3.78 ± 0.8 for p-Ti, and 2.68 ± 0.6 for sb-YTZP. The difference was not significant between sb-YTZP and p-Ti. θ (mean ± SD) was 55.6 ± 5.6 for m-Ti, 48.7 ± 2.8 for sb-YTZP, and 38.0 ± 2.2 for p-Ti. The difference was not significant between m-Ti and sb-YTZP. Conclusions The sb-YTZP demonstrated a significantly lesser amount of bce compared with p-Ti specimens, notwithstanding that any significant difference was present between Ra and θ.

Background Differences in implant microtexture are important in conditioning the bone response around dental implants. Purpose The aim of the present study was an evaluation of the bone response in machined (M), blasted with apatitic calcium phosphate (tricalcium phosphate/hydrossyapatite [HA] blend) particles (resorbable blast texturing [RBT]), and coated with HA implants. Methods A total of 48 (16 M, 16 RBT, and 16 HA) threaded screw-shaped implants were inserted into the tibia of 12 rabbits. The specimens were retrieved after 1, 2, 4, and 8 weeks and processed for histology. Results All experimental groups showed an increase of the bone-implant contact percentages through the study period. Higher and highly statistically significant differences were found in the percentages of bone observed in the concavities rather than in the convexities of the implants retrieved after 1, 2, and 4 weeks, while no significant differences were found after 8 weeks. In the different time periods, higher percentages of bone-implant contact were found in the RBT and HA-coated implants both in the concavities and in the convexities, but these differences were not statistically significant. Conclusions The newly formed bone present in the concavity of the threads was not influenced by the implant surface in the first healing period, while after 4 to 8 weeks, the percentage of bone observed in the concavities and convexities was similar. Additional histological studies are necessary to further evaluate the critical role of the concave geometry in bone differentiation and formation around dental implants.

The use of the conical coupling connection to support definitive restorations was evaluated in cases involving full acrylic resin or hybrid acrylic resin-composite prostheses. The aim of this study was to evaluate the performance of definitive fixed partial prostheses made with lithium disilicate and supported by coupling connection abutments and healed implants.The prostheses were placed in the posterior regions of partially edentulous patients; 65 patients received fixed lithium disilicate restorations splinted with conical coupling connections to two implants. Implants were placed into healed sites and fresh extraction sockets. The prostheses were placed after healing periods of 3 months: restorations were followed yearly for 3 years. At each follow-up visit, peri-implant bone levels and pocket depths were recorded. Esthetic, functional, and biologic United States Public Health Services (USPHS) parameters modified by the FDI World Dental Federation study design were assessed at the last follow-up appointments.Two prostheses (3.07%) fractured: one was related to framework design error; one was caused by a car accident. Three patients reported small chips: these restorations were immediately polished. No significant difference involving peri-implant bone and probing levels between the experimental times were found. None of the prostheses became loose.The results of this research indicated that abutment-prostheses coupling connections were successful within the timeframe of this study.

The aim of this prospective study was to demonstrate the feasibility of the conic coupling connection as a novel approach for the retention of immediately loaded, titanium-reinforced, temporary fixed partial restorations. The patients received a fixed, immediate partial restoration, attached using the conic coupling connection to two implants placed in a fresh extraction socket. Changes in marginal peri-implant bone level or probing depth measurements, biologic or technical complications, and any other adverse event were recorded at yearly follow-ups up to 3 years after implantation. A total of 78 implants placed in 39 patients reached the 3-year follow-up. A trend of bone overgrowth over the implant platform (mean: 0.2 mm) and a complete fill of the vertical gap between the implant platform level and the first point of contact of the bone with the implant surface was seen after the 6-month follow-up. No disconnection of any prosthesis was noted during 3 years of full occlusal function. The results of this study suggest that titanium-reinforced, temporary partial restorations with conic coupling retention supported by immediate implants provide a successful, cost-effective treatment modality.

Sinus augmentation procedure has been demonstrated to be a highly predictable treatment in posterior maxilla atrophy. All the surgical interventions in the maxillary region require deep knowledge of anatomy and possible anatomical variations. In this article, pre-operative and post- operative assessments of sinus cavity as well as novel approaches to deepen our knowledge of the behavior of bone substitute materials are described. The awareness of the patient's morphologic conditions enables exact planning of invasive surgery and aids to avoid complications. Pre- operative radiologic evaluation of the region before sinus lift is advisable both for a planning of the sinus augmentation and for selection and alignment of the optimum placement of implants. On the orthopantomography it is possible to measure the vertical dimension of graft, but not the volume and 3D changes. Cone-beam computed tomography (CBCT) has become the "gold standard" to plan a comprehensive implant treatment and to achieve a post-operative assessment. A computer-aided design/computer-aided manufacturing (CAD/CAM) technique is proposed to produce custom-made block grafts for sinus lift procedure, and a customized cutting guide to accurately place the lateral wall and ease membrane elevation. This procedure allows to reduce intervention time, to precisely adapt the scaffold, to reduce risk of complications and to improve operation quality. Recently, a novel approach has been used to deepen our knowledge of the behavior of BSBs: by means of synchrotron micro-tomography (SCT). It is a 3-D analyzing method, suitable to examine the dynamic and spatial arrangement of regenerative phenomena in complex anatomical structures such as bone, where tissues with several morphologies (alveolar process, unmineralized extracellular matrix, regenerated vessels, etc.) compete to achieve the final goal of bone regeneration.

Over the past decades, the technological development in the medical field, coupled with the ongoing scientific research, has led to the development and improvement of dental prostheses supported by screw-retained metal frameworks. A key point in the manufacture of the framework is the achievement of a passive fit, intended as the capability of an implant-supported reconstruction to transmit minimum strain to implant components as well as to the surrounding bone, when subject to any load. The fitting of four different kinds of screw-retained metal frameworks was tested in this article. They differ both in materials and manufacturing process: two frameworks are made by casting, one framework is made by computer-aided design and computer-aided manufacturing and one framework is made by electric resistance spot welding (WeldONE, DENTSPLY Implants Manufacturing GmbH, Mannheim, Germany). The passivity of the frameworks was evaluated on the entire system, composed of a resin master cast, the implant analogues embedded in the cast and the frameworks. Strains were recorded by means of an electrical strain gauge connected to a control unit for strain gauge measurements. The experimental tests were carried out in the laboratories of the Department of INdustrial engineering at the University of Bologna. The results of the test campaigns, which compared three samples for each technological process, showed that no significant differences exist between the four framework types. In particular, the frameworks made by the resistance welding approach led to a mechanical response that is well comparable to that of the other tested frameworks.

The presence of a microgap between implant and abutment could produce a bacterial reservoir which could interfere with the long-term health of the periimplant tissues. The aim of this article was to evaluate, by x-ray 3-dimensional microtomography, implant-abutment contact surfaces and microgaps at the implant-abutment interface in different types of implant-abutment connections.A total of 40 implants were used in this in vitro study. Ten implants presented a screw-retained internal hexagon abutment (group I), 10 had a Morse Cone taper internal connection (group II), 10 another type of Morse Cone taper internal connection (group III), and 10 had a screwed trilobed connection (group IV).In both types of Morse Cone internal connections, there was no detectable separation at the implant-abutment in the area of the conical connection, and there was an absolute congruity without any microgaps between abutment and implant. No line was visible separating the implant and the abutment. On the contrary, in the screwed abutment implants, numerous gaps and voids were present.The results of this study support the hypothesis that different types of implant-abutment joints are responsible for the observed differences in bacterial penetration.

Control of heat dissipation and transmission to the peri-implant area during intra-oral welding is very important to limit potential damage to the surrounding tissue. The aim of this in vitro study was to assess, by means of thermal infrared imaging, the tissue temperature peaks associated with the thermal propagation pathway through the implants, the abutments and the walls of the slot of the scaffold, generated during the welding process, in three different implant systems. An in vitro polyurethane mandible model was prepared with a 7.0 mm v-shape slot. Effects on the maximum temperature by a single welding procedure were studied using different power supplies and abutments. A total of 36 welding procedures were tested on three different implant systems. The lowest peak temperature along the walls of the 7.0 mm v-shaped groove (31.6 ± 2 °C) was assessed in the specimens irrigated with sterile saline solution. The highest peak temperature (42.8 ± 2 °C) was assessed in the samples with a contemporaneous power overflow and premature pincers removal. The results of our study suggest that the procedures used until now appear to be effective to avoid thermal bone injuries. The peak tissue temperature of the in vitro model did not surpass the threshold limits above which tissue injury could occur.

Coating characteristics of dental implants such as composition and topography regulate cell response during implant healing. The aim of this study was to assess how surface topography can affect osteogenic differentiation of mesenchymal stem cells (MSCs) by analyzing the expression levels of bone-related genes and MSCs marker. Thirty disk-shaped, commercially pure Grade 2 titanium samples (10 × 2 mm) with 3 different surface topographies (DENTSPLY-Friadent GmbH, Mannheim, Germany) were used in the present study: 10 Ti machined disks (control), 10 Ti sandblasted and acid-etched disks (DPS(®)) and 10 sandblasted and acid-etched disks at high temperature (Plus(®)). Samples were processed for real-time reverse transcription-polymerase chain reaction (RT-PCR) analysis. By comparing machined and Plus(®) disks, quantitative real-time RT-PCR showed a significant reduction of the bone-related genes osteocalcin (BGLAP) and osteoblast transcriptional factor (RUNX2). The comparison between DPS(®) and Plus(®) disks showed a slight induction of all the genes examined (RUNX2, ALPL, COL1A1, COL3A1, ENG, FOSL1, SPP1, and SP7); only the expression of BGLAP remained stable. The present study, demonstrated that implant surface topography affects osteoblast gene expression. Indeed, Plus(®) surface produces an effect on MSCs in the late differentiation stages.

Stability of peri-implant crestal bone plays a relevant role relative to the presence or absence of interdental papilla. Several factors can contribute to the crestal bone resorption observed around two-piece implants, such as the presence of a microgap at the level of the implant-abutment junction, the type of connection between implant and prosthetic components, the implant positioning relative to the alveolar crest, and the interimplant distance. Subcrestal positioning of dental implants has been proposed to decrease the risk of exposure of the metal of the top of the implant or of the abutment margin, and to get enough space in a vertical dimension to create a harmoniously esthetic emergence profile.The present retrospective histologic study was performed to evaluate dental implants retrieved from human jaws that had been inserted in an equicrestal or subcrestal position. A total of nine implants were evaluated: five of these had been inserted in an equicrestal position, whereas the other four had been positioned subcrestally (1 to 3 mm).In all subcrestally placed implants, preexisting and newly formed bone was found over the implant shoulder. In the equicrestal implants, crestal bone resorption (0.5 to 1.5 mm) was present around all implants.The subcrestal position of the implants resulted in bone located above the implant shoulder.

Objectives: The aim of this prospective study was to assess the effects of abutment removal after 6 months on bone healing after the subcrestal placement of immediately restored, tapered implants in cases of partial posterior mandibular edentulism. Material and methods: Each of the 24 patients with partial posterior mandibular edentulism was consecutively treated with two immediately restored 3.5 mm diameter tapered implants. A total of 48 implants were placed in healed sites and immediately splinted with a temporary restoration, which was placed in such a way as to avoid occlusal contact. Twenty-four weeks after surgery, 12 patients underwent the standard prosthetic protocol: the abutments were removed and impressions were made directly on the implant platform. Twelve patients underwent the “one abutment at one time” protocol: impressions were made of the abutments using snap-on abutment copies. The final restoration was delivered approximately 6 months after implant insertion. Vertical and horizontal bone changes were assessed using periapical radiographs immediately after surgery and at 6-, 12-, 24- and 36-month follow-up examinations. Results: All implants osseointegrated and were clinically stable at the 6-month follow-up. No statistically significant difference was evidenced between the two groups regarding the measurement of vertical bone healing. A small but significant horizontal bone loss was evidenced in the hard tissue portion over the implant platform in the period of time between the 6-month and 1-year follow-up in the control group. Conclusions: The non-removal of an abutment placed at the time of surgery results in a statistically significant reduction of the horizontal bone remodeling around the immediately restored, subcrestally placed, tapered implant in cases of partial posterior mandibular edentulism. To cite this article: Degidi M, Nardi D, Piattelli A. One abutment at one time: non-removal of an immediate abutment and its effect on bone healing around subcrestal tapered implants. Clin. Oral Impl. Res. 22, 2011; 1303–1307. doi: 10.1111/j.1600-0501.2010.02111.x

The long-term high percentages of survival and success of dental implants reported in the literature are related mainly to new, innovative implant and thread designs, and new implant surfaces that allow to obtain very good primary and secondary stability in most anatomical and clinical situations, even in low quality and quantity of bone, promoting a more rapid osseointegration. The aim of this retrospective study was a histological and histomorphometrical evaluation of the bone response around implants with a parallel-wall configuration, condensing thread macrodesign, and self-tapping apex, retrieved from man for different causes. A total of 10 implants were reported in the present study, and these implants had been retrieved after a loading period comprised between a few weeks to about 8 years. Mineralized newly formed bone was found at the interface of all the implants, in direct contact with the implant surface, with no gaps or connective fibrous tissue. This bone adapted very well to the microirregularities of the implant surface. Areas of bone remodeling were present in some regions of the interface, with many reversal lines. High bone-implant contact percentages were found. In conclusion, both the macrostructure and the microstructure of this specific type of implant could be very helpful in the long-term high survival and success implant percentages.