The association of Morse taper implant-abutment design with the use of a smaller abutment diameter (platform switching) may improve dental implant success rate and prevent peri-implant bone loss. The aim of the present study was to histologically and histomorphometrically evaluate the behavior of peri-implant tissues around an implant with a conical connection associated with platform switching. A platform-switched Morse-cone connection implant was inserted in the left posterior mandible of a 61-year-old patient. The implant was inserted at the level of the alveolar crest. After 11 months from placement and 6 months of loading, the implant was retrieved for psychological reasons and processed for histological evaluation. The retrieved implant was wholly surrounded by bone tissue, except for a small area in the apical portion. At higher magnification, in the coronal portion of the implant, it was possible to observe bone directly at the implant platform level. No resorption of the coronal bone was present, except for 0.2 mm on the vestibular aspect. Crestally, bone remodeling with areas of newly formed bone was detected; the bone-implant contact was 73.9%. Apposition of bone was detected even upon the platform. Peri-implant crestal bone preservation can be achieved with the combination of Morse taper conical internal implant-abutment connection with the use of a smaller abutment diameter (platform-switching).

No well-established evidence supporting safe use of bisphosphonates (BPs) or other antiresorptive agents prior, during, or after dentoalveolar surgery, are currently available; moreover, the real risk of osteonecrosis of the jaw (ONJ) development is still unknown. The aim of the present systematic review was to assess the scientific literature concerning the implants placement in antiresorptive agent users and the related risk of implants failure and ONJ development. English papers published from January 2003 until December 2014 were identified on the MEDLINE database. Titles and abstracts retrieved form electronic search were screened separately by 2 examiners; thus, original studies dealing with dental implants placement during or before bone antiresorptive agent therapy and the relative risk of implant failure or development of osteonecrosis were evaluated. Due to the heterogeneity of the included studies and the high risk of bias, there is no evidence of the safe use of oral antiresorptive agents prior or after dental implant surgery. Indeed, implant failure and ONJ development can occur and represent a devastating side effect that should be considered during treatment. Within the limitation of the present systematic review, high quality studies are needed to provide an adequate level of evidence regarding the safety of dentoalveolar surgery during or before bone resorption inhibition therapy and the increase predisposition to osteonecrosis of the jaw (ONJ) development. Therefore, antiresorptive agent therapy should be considered a risk factor until further evidence is prospectively obtained.

Analysis of human retrieved dental implants is a useful tool in the evaluation of implant success and failure. More human histological data are needed from samples of long-term implant service. The aim of the present case series was a histological and histomorphometrical evaluation of the peri-implant bone responses in implants retrieved for fracture after more than 20 years loading. The archives of the Implant Retrieval Center of the Department of Medical, Oral and Biotechnological Sciences of the University of Chieti-Pescara, Italy were searched. A total of 5 implants, retrieved after a loading period of more than 20 years, were found: 2 had been retrieved after 20 years, 1 after 22 years, 1 after 25 years, and 1 after 27 years. All these implants were histologically processed. Compact, mature bone in close contact with the implant surface was observed in all specimens, with no gaps or connective tissue at the interface. Bone in different maturation stages was found around some implants. Primarily newly formed bone was observed in proximity of the implant surface, while mature compact bone with many remodeling areas and cement lines were detected in areas distant from the implant. Many primary and secondary osteons were present. Bone to implant contact percentage varied from 37.2% to 76%. In conclusion, histology and histomorphometry showed that even after many years of function, all implants presented more than adequate bone to implant contact and they appeared to be very well integrated in the peri-implant bone.

In this study, the in vivo behavior of a custom-made three-dimensional (3D) synthetic bone substitute was evaluated when used as scaffold for sinus augmentation procedures in an animal model. The scaffold was a calcium phosphate ceramic fabricated by the direct rapid prototyping technique, dispense-plotting. The geometrical and chemical properties of the scaffold were first analyzed through light and electron scanning microscopes, helium picnometer, and semi-quantitative X-ray diffraction measurements. Then, 6 sheep underwent monolateral sinus augmentation with the fabricated scaffolds. The animals were euthanized after healing periods of 45 and 90 days, and block sections including the grafted area were obtained. Bone samples were subjected to micro computerized tomography, morphological and histomorphometric analyses. A complete integration of the scaffold was reported, with abundant deposition of newly formed bone tissue within the biomaterial pores. Moreover, initial foci of bone remodeling were mainly localized at the periphery of the implanted area after 45 days, while continuous bridges of mature lamellar bone were recorded in 90-day specimens. This evidence supports the hypothesis that bone regeneration proceeds from the periphery to the center of the sinus cavity. These results showed how a technique allowing control of porosity, pore design, and external shape of a ceramic bone substitute may be valuable for producing synthetic bone grafts with good clinical performances.

Several procedures have been proposed to achieve maxillary ridge augmentation. These require bone replacement materials to be manually cut, shaped, and formed at the time of implantation, resulting in an expensive and time-consuming process. In the present study, we describe a technique for the design and fabrication of custom-made scaffolds for maxillary ridge augmentation, using three-dimensional computerized tomography (3D CT) and computer-aided design/computer-aided manufacturing (CAD/CAM). CT images of the atrophic maxillary ridge of 10 patients were acquired and modified into 3D reconstruction models. These models were transferred as stereolithographic files to a CAD program, where a virtual 3D reconstruction of the alveolar ridge was generated, producing anatomically shaped, custom-made scaffolds. CAM software generated a set of tool-paths for manufacture by a computer-numerical-control milling machine into the exact shape of the reconstruction, starting from porous hydroxyapatite blocks. The custom-made scaffolds were of satisfactory size, shape, and appearance; they matched the defect area, suited the surgeon's requirements, and were easily implanted during surgery. This helped reduce the time for surgery and contributed to the good healing of the defects.

Prevention of microbial leakage at the implant-abutment junction is a major challenge for the construction of 2-stage implants in order to minimize inflammatory reactions and to maximize bone stability at the implant neck. The aim of the present in vitro study was an evaluation of the leakage observed over a period of 28 days in Cone Morse taper internal connections and in screwed-abutments connections. In the present study 10 specimens of Cone Morse (Group 1) and 10 of internal hexagon (Group 2) implants were used. The inner parts of 5 implants per group were inoculated with Pseudomonas aeruginosa (PS) suspension and 5 implants per group with Aggregatibacter actinomycetemcomitans (AA). The possible penetration of bacterial suspension into the surrounding solution was determined by the observation of turbidity of the broth. In Group 1, bacterial contamination was found in 3 out of 5 implant-abutment assemblies seeded with the PS and in 2 samples out of 5 in the assemblies seeded with AA, with a total of leaked assemblies in this group of 5 out of 10. In Group 2, bacterial contamination was found in 4 out of 5 implant-abutment assemblies seeded with the PS, and in 4 out of 5 samples seeded with AA, with a total of leaked assemblies of 8 out of 10. The present data confirm the reported high permeability to bacterial leakage of screw-retained abutment connections, and the lower infiltration rates— although not significantly —of Cone Morse taper internal connections.

The long-term fate of some biomaterials is still unknown, and the reports present in the literature are not conclusive as to whether these biomaterials are resorbed over time or not. Different reports can be found with regard to the resorption behavior of anorganic bovine bone (ABB). The aim of the present study was to provide a comparative histological and histomorphometrical evaluation, in the same patient, of 2 specimens retrieved from a sinus augmented with ABB and with anorganic bovine matrix added to a cell-binding peptide (PepGen P-15), respectively, after a healing period of 6 months and after 8 years of implant loading, to evaluate the resorption of both biomaterials. A unilateral sinus augmentation procedure with ABB (50%) and with PepGen P-15 (50%) was performed in a 54-year-old male patient. Two titanium dental implants with a sandblasted and acid-etched surface were inserted after 6 months. During this procedure, 2 tissue cores were retrieved from the sinus with a trephine, before implant insertion. After an additional 6 months, a fixed prosthetic restoration was fabricated. One of these implants, after a loading period of 8 years, fractured in the coronal portion and was removed. Both specimens, one retrieved after a 6-month healing period and the other after an 8-year loading period, were treated to obtain thin ground sections. In the 6-month specimen, the histomorphometry showed that the percentage of newly formed bone was 27.2% ± 3.6%, marrow spaces 35.6% ± 2.3%, residual ABB particles 25.1% ± 1.2%, and residual PepGen P-15 particles 12.1% ± 2.2%. In the 8-year specimen, the histomorphometry showed that the percentage of newly formed bone was 51.4% ± 4.8%, marrow spaces 40% ± 7.1%, residual ABB particles 6.2% ± 0.7%, and residual PepGen P-15 particles 2.4% ± 0.5%. Both biomaterials underwent significant resorption over the course of this study.

The aim of this study was to compare the esthetic outcome of single implants placed in fresh extraction sockets with those placed in fully healed sites of the anterior maxilla. This retrospective study was based on data from patients treated with single-tooth Morse taper connection implants placed in fresh extraction sockets and in fully healed sites of the anterior maxilla. Only single implant treatments were considered with both neighboring teeth present. Additional prerequisites for immediate implant treatment were intact socket walls and a thick gingival biotype. The esthetic outcome was objectively rated using the pink esthetic/white esthetic score (PES/WES). The Mann-Whitney U test was used to compare the PES and the WES between the 2 groups. Twenty-two patients received an immediate implant, and 18 patients had conventional implant surgery. The mean follow-up was 31.09 months (SD 5.57; range 24–46) and 34.44 months (SD 7.10; range 24–48) for immediately and conventionally inserted implants, respectively. No implants were lost. All implants fulfilled the success criteria. The mean PES/WES was 14.50 (SD 2.52; range 9–19) and 15.61 (SD 3.20; range 8–20) for immediately and conventionally placed implants, respectively. Immediate implants had a mean PES of 7.45 (SD 1.62; range 4–10) and a mean WES of 7.04 (SD 1.29; range 5–10). Conventional implants had a mean PES of 7.83 (SD 1.58; range 4–10) and a mean WES of 7.77 (SD 1.66; range 4–10). The difference between the 2 groups was not significant. Immediate and conventional single implant treatment yielded comparable esthetic outcomes.

This histologic report evaluated the early human bone response to a direct laser metal sintering implant surface retrieved after a short period of healing. A selective laser sintering procedure using a Ti-6Al-4V alloy powder with a particle size of 25–45 µm prepared this surface topography. One experimental microimplant was inserted into the anterior mandible of a patient during conventional implant surgery of the jaw. The microimplant and surrounding tissues were removed after 2 months of unloaded healing and were prepared for histomorphometric analysis. Histologically, the peri-implant bone appeared in close contact with the implant surface, whereas marrow spaces could be detected in other areas along with prominently stained cement lines. The mean of bone-to-implant contact was 69.51%. The results of this histologic report suggest that the laser metal sintering surface could be a promising alternative to conventional implant surface topographies.

Smoking has adverse effects on peri-implant bone healing and can cause bone loss around successfully integrated implants placed on type IV bone. This study evaluated the influence of implant surface topography of microimplants retrieved from posterior maxilla of smokers after 2 months of unloaded healing. Seven partially edentulous patients received 2 microimplants (machined and sandblasted acid-etched surface) each during conventional implant surgery. Histometric evaluation showed that the mean bone to implant contact was 10.40 ± 14.16% and 22.19 ± 14.68% to machined and sandblasted acid-etched surfaces, respectively ( P < .001). These data suggest that the sandblasted acid-etched surface presented better results than the machined surface after a short healing time in smokers.

Fracture of the implant is one of the possible complications affecting dental implants; it is a rare event but of great clinical relevance. The aim of the present study was to perform a scanning electron microscopy (SEM) fractography evaluation of 7 International Team for oral Implantology (ITI) hollow implants removed because of fracture. The most common clinical risk factors, such as malocclusion, bruxism, and cantilevers on the prosthesis, were absent. Seven fractured ITI hollow implants were retrieved from 5 patients and were analyzed with the use of SEM. SEM analysis showed typical signs of a cleavage-type fracture. Fractures could be due to an association of multiple factors such as fatigue, inner defects, material electrochemical problems, and tensocorrosion.

Osteoporosis is a disease that influences the quality of bone tissue. At present, osteoporosis represents a contraindication or a risk factor for osseointegration. The aim of this report was to evaluate the bone-to-implant contact of 2 loaded implants retrieved after prosthetic failure in a woman with type 1 osteoporosis. Histologically, only one implant was osseointegrated, and it appeared surrounded by healthy bone tissue. The bone-to-implant contact presented a mean of 51.25%. No foreign body reaction was found at the bone-to-implant contact, although epithelial downgrowth was observed at the interface. Data from this case report demonstrate that the peri-implant bone histology of the dental implant retrieved from an osteoporotic patient presented no alteration. However, the role of osteoporosis in the long-term success of dental implants needs further investigation.

The aim of this study is a comparative histological and histomorphometrical evaluation of the effect on early bone formation of 2 different implant surfaces: a machined and a new acid-etched implant surface (Leader, Milano, Italy). Ten screw-type microimplants were placed in 5 patients. Each patient received 2 microimplants (2 mm in diameter and 5 mm in length): 1 with a machined surface (control) and 1 with an acid-etched surface (test). The microimplants were retrieved after 60 days of healing with a 4-mm trephine bur and processed for histology. Moreover, 24 regular size implants—12 with a machined surface (control) and 12 with an acid-etched surface (test)—were placed in 2 adult nonhuman primates 3 months after the extraction of premolars and molars. Each animal received 3 machined implants (control) in the right hemimandible and 3 acid-etched implants (test) in the left hemimandible. The same animals received 3 control implants and 3 test implants in the rectus abdominis muscle. After 1 month, the implants were retrieved from the mandible and the rectus abdominis muscle and processed for histology. Histomorphometric evaluation demonstrated a higher bone-to-implant contact in the test implants compared with the controls in both primates (25.55% vs 15.8%) and humans (62% vs 45%). Moreover, in nonhuman primates after 1 month of healing, it was possible to observe a poor osseointegration in the control specimens, while newly formed bone in direct contact with test implants was evident. The rectus abdominis muscle specimens showed that the acid-etched surfaces can stimulate the formation and attachment of new connective and vascular tissues more than machined surfaces can. Implant surface geometry can speed up bone formation by the development of a special microenvironment that promotes angiogenesis. Long-term studies are needed to further test this new acid-etched implant surface.

The aim of this study was to evaluate the microbiota and surface of failed titanium dental implants from 4 manufacturers. Twelve mobile dental implants were retrieved from 10 smokers after 3 to 10 years of functional loading. Before implant removal, microbial samples were taken and evaluated using polymerase chain reaction. After implant removal, analyses of the failed implant surfaces were performed using scanning electron microscopy and energy-dispersive spectrometer x-ray. Periodontal pathogens such as Aggregactibacter actinomycetemcomitans , Campylobacter rectus , Eikenella corrodens , Fusobacterium nucleatum , Porphyromonas gingivalis , Prevotella intermedia , Tannerella forsythia , and Treponema denticola were detected in all implants in different proportions. Surface analysis showed varying degrees of surface roughness between the samples and the presence of proteinaceous material, appearing mainly as dark stains. Foreign carbon, oxygen, sodium, calcium, aluminum, and silicon elements were also found. Although no material-related causes of implant failure were detected, several periodontal pathogens were identified independently of the surface topography or manufacturer.

Little is known about the in vivo healing processes at the interface of implants placed in different grafting materials. For optimal sinus augmentation, a bone graft substitute that can regenerate high-quality bone and enable the osseointegration of load-bearing titanium implants is needed in clinical practice. Calcium sulphate (CaS) is one of the oldest biomaterials used in medicine, but few studies have addressed its use as a sinus augmentation material in conjunction with simultaneous implant placement. The aim of the present study was to histologically evaluate an immediately loaded provisional implant retrieved 7 months after simultaneous placement in a human sinus grafted with CaS. During retrieval bone detached partially from one of the implants which precluded its use for histologic analysis. The second implant was completely surrounded by native and newly formed bone, and it underwent histologic evaluation. Lamellar bone, with small osteocyte lacunae, was present and in contact with the implant surface. No gaps, epithelial cells, or connective tissues were present at the bone–implant interface. No residual CaS was present. Bone–implant contact percentage was 55% ± 8%. Of this percentage, 40% was represented by native bone and 15% by newly formed bone. CaS showed complete resorption and new bone formation in the maxillary sinus; this bone was found to be in close contact with the implant surface after immediate loading.

The aim of this preliminary study was to evaluate the influence of a sandblasted acid-etched surface on bone-implant contact percentage (BIC%) as well as the bone density in the threads area (BD%) in type 4 bone after 2 months of unloaded healing. Five subjects (mean age = 42.6 years) received 2 microimplants each during conventional implant surgery in the posterior maxilla. The microimplants with commercially pure titanium surface (machined) and sandblasted acid-etched surface served as the control and test surfaces, respectively. After a healing period of 2 months, the microimplants and the surrounding tissue were removed and prepared for ground sectioning and histomorphometric analysis. One microimplant with a machined surface was found to be clinically unstable at the time of retrieval. Histometric evaluation indicated mean BIC% was 20.66 ± 14.54% and 40.08 ± 9.89% for machined and sandblasted acid-etched surfaces, respectively ( P = .03). The BD% was 26.33 ± 19.92% for machined surface and 54.84 ± 22.77% for sandblasted acid-etched surface ( P = .015). Within the limits of this study, the data suggest that the sandblasted acid-etched implant surface presented a higher percentage of bone-implant contact compared with machined surfaces, under unloaded conditions in posterior maxilla after a healing period of 2 months.

Immediate loading is a surgical-prosthetic procedure extensively used in implant dentistry. Despite its frequent use, minimal data are available on the long-term clinical success rate of immediate functional loading (IFL) and immediate nonfunctional loading (INFL) of implants. The aim of this study was to evaluate the long-term survival and bone loss of immediate nonfunctional single implant restorations in a group of patients that were monitored for 5 years. One hundred and eleven patients (41.4% men) with a median age of 40 years were included in this study. A total of 111 implants were placed. All implants were placed with a minimum insertion torque of 25 Ncm. A temporary restoration was relined with acrylic resin, trimmed, polished, and cemented or screw-retained 1 to 2 hours later. Occlusal contact was avoided in centric and lateral excursions. After provisional crown delivery, a periapical radiograph was performed by means of a customized Rinn holder device. Data were analyzed by means of Kaplan-Meier and life-table algorithms. Stratification of implant survival was performed for the available variables of interest, and comparisons were analyzed using a log-rank test. Investigated parameters were time of implant placement, bone quality, implant site, implant diameter and length, and type of implant surface enhancement. The parameters for overall success rate were defined by bone resorption <1.5 mm after the first year of loading and <0.2 mm thereafter. During the 5-year follow-up period, a survival rate of 95.5% was observed. All failures occurred within 4 months of implant loading. There were statistically significant differences regarding healed vs post-extraction implant sites (100% and 92.5%, respectively, P = .05) and type of bone (D1 vs D4 yielded 100% and 95.5%, respectively, P < .05). No differences were detected for: (1) site (100% for mandible and 94.6% for maxilla, P = .319); (2) implant diameter (survival rates of 97.26% for <4.5-mm diameter and 92.11% for >4.5-mm diameter, P = .206); (3) implant lengths (survival rates of 96.97% for implants >13 mm and 94.87% for implants <13 mm, P = .624); and (4) type of implant surface enhancement (survival rates of 94.03% for 67 cases of grit-blasted and acid-etched surfaces and a failure rate of 4 out of 5, and 94.12% for 17 cases of hydroxyapatite (HA)-coated surfaces with only 1 failure). The success rate (defined as bone resorption >1.5 mm after the first year of loading and >0.2 mm thereafter) was 97.2%. Immediate nonocclusal loading of single implants is a reliable surgical-prosthetic procedure with a low rate of implant loss and a low quantity of peri-implant bone loss over time.

Immediate loading of dental implants offers treatment cost advantages to patients and avoids the functional and psychological problems caused by the wearing of provisional dentures. There is evidence that the amount of transverse collagen fiber orientation in bone is influenced by mechanical stresses and strains. Two osseointegrated dental implants in humans were used in the present study. Two implants inserted in the maxilla were analyzed: 1 short-term implant (implant A) immediately loaded and retrieved after 4 months of loading and 1 long-term implant (implant B) immediately loaded and retrieved after 12 years. We hypothesized that the bone functional strain caused by immediate loading correlated well with the collagen fiber organization occurring after both short- and long-term functional healing. Circularly polarized light (CPL) was used to assess the area fraction extension related to the transverse collagen fiber orientation in the bone matrix. After evaluating a total of 68 digitized images taken at ×50 magnification, birefringence measurements were performed all around the implant surfaces by using 2 central sections from each implant. The results showed that the bone-to-implant contact (BIC) percentage for implant A was 67.9% ± 9.5% (mean ± SD), whereas the BIC percentage for implant B was 74.6% ± 11.2% (mean ± SD). The area fraction extension was 2.7% ± 1.4 % (mean ± SD) for implant A, whereas the area fraction extension was 4.7% ± 1.2% (mean ± SD) for implant B. The CPL measurements of the birefringence for transverse collagen fibers of implant A vs implant B indicated that the bone fraction area difference was not high. In the bone near both dental implants, no differences were found in the amount of transverse collagen fibers. Immediate loading seemed to determine and maintain the collagen fiber's orientation over a long period.

Immediate loading of root-form dental implants has shown promising results and offers treatment cost and convenience advantages to patients. Although blade implants have been immediately loaded for over 2 decades, the ability of this implant design to achieve osseointegration has been debated. The aim of the present study was to histologically evaluate the peri-implant tissues of an immediately loaded blade implant retrieved for abutment fracture after a 20-year loading period. Histologic samples were prepared and examined by light microscope. Compact, cortical, mature bone with well-formed osteons was present at the interface of the implant. Bone-to-implant contact was 51% ± 6%. The histologic data showed that osseointegration was obtained in an immediately loaded blade implant inserted into the mandible, and that mineralized tissues were maintained at the interface over a long period (20 years).

Porous hydroxyapatite (HA) is a calcium-phosphate–based material that is biocompatible, nonimmunological, and osteoconductive, and has a macroporosity of about 200 to 800 μm. The pores seem to be able to induce migration, adhesion, and proliferation of osteoblasts inside the pore network and to promote angiogenesis inside the pore system. The aim of this study was to evaluate the clinical behavior and the histological and ultrastructural aspects of porous HA in maxillary sinus augmentation procedures. Twenty-four patients (19 men, 5 women; average age 53.4 years) in good general physical and mental health and with partially or completely edentulous maxillae were selected for this study. Six months after sinus floor elevation, at the time of dental implant placement, biopsies were carried out under local anesthesia. These bone cores were cut in half and were processed for light and transmission electron microscopy. After a mean 3 years after implantation, all implants are clinically in function and no surgical or prosthetic complications have occurred. Under light microscopy, newly formed bone was 38.5% ± 4.5%, whereas the residual biomaterial represented 12% ± 2.3% and the marrow spaces represented 44.6% ± 4.2%. In addition, in the majority of cases, the biomaterial particles were in close contact with the bone, which appeared compact with the characteristic features of well-organized lamellar bone. A cement-like line was slightly visible at the bone-biomaterial interface, but there were no gaps or interposed connective tissue in between. A high quantity (about 40%) of newly formed bone was present. Bone was closely apposed to the biomaterials particles as shown in light microscopy and transmission electron microscopy. Moreover, no signs of inflammatory cell infiltrate or foreign body reaction were present. Also, most of the biomaterial was resorbed and only a small quantity (a little more than 10%) was still present. The results of our study show that porous HA can be a suitable synthetic material for bone regeneration in maxillary sinus augmentation procedures.