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: The aim of this study was to compare the bone loss pattern and soft tissue healing of immediately versus one‐stage loaded 3.0‐mm‐diameter implants in cases involving a single missing ...lateral maxillary incisor.
Methods: Sixty patients with a missing lateral incisor in the maxilla were randomized to one of the treatments: 30 patients in the immediate‐restoration group and 30 patients in the one‐stage group. All implants were placed in healed sites and had to be inserted with a torque >25 Ncm. The implants in the immediate‐restoration group were fitted with a non‐occluding temporary crown on the day of surgery. Both groups received a full occluding final crown 6 months after surgery. Mean marginal bone loss, probing depth, and bleeding on probing were assessed at 6‐, 12‐, 24‐, and 36‐month follow‐up examinations by a masked examiner.
Results: Sixty 3.0‐mm‐diameter implants were placed between July 2003 and February 2006; 27 (45.0%) were in men, and 33 (55.0%) were in women. All implants osseointegrated and were clinically stable at the 6‐month follow‐up. No statistically significant differences were observed for bleeding or plaque index. No implant fractures occurred. At the 36‐month follow‐up, the accumulated mean marginal bone loss and probing depth were 0.85 ± 0.71 mm and 1.91 ± 0.59 mm, respectively, for the immediate‐loading group (n = 30) and 0.75 ± 0.63 mm and 2.27 ± 0.81 mm, respectively, for the one‐stage group (n = 30). There was no statistically significant difference (P >0.05) for the tested outcome measures between the two procedures.
Conclusions: In the rehabilitation of a single missing lateral maxillary incisor, no statistically significant difference was assessed between immediately and one‐stage restored small‐diameter implants with regard to implant survival, mean marginal bone loss, and probing depth. Three‐millimeter‐diameter implants proved to be a predictable treatment option in our test and control groups if a strict clinical protocol was followed.
Purpose The purpose of this present study was to investigate the relation between implant site underpreparation and primary stability in the presence of poor-quality bone. Materials and Methods A ...study was performed on fresh humid bovine bone; samples presented no cortical layer with a cancellous structure inside and were obtained from the hip. The bones were firmly attached to a base device. Sixty sites were prepared according to the protocol provided by the manufacturer: a 2-mm pilot drill was introduced to the proper depth and then twist drills of 3 and 3.4 mm were used. After site preparation, 20 3.4- × 11-mm (standard protocol group), 20 3.8- × 11-mm (10% undersized group), and 20 4.5- × 11-mm (25% undersized group) implants were inserted at a calibrated maximum torque of 70 N-cm at the predetermined speed of 30 rpm. After implant insertion, variable torque work (VTW), maximum insertion torque (peak IT), and resonance frequency analysis (RFA) values were recorded. Results The standard protocol group showed a mean VTW of 565.77 ± 219.12 N-cm, a peak IT of 11.3 ± 4.44 N-cm, and an RFA of 69.35 ± 7.35 implant stability quotient (ISQ). The 10% undersized group showed a mean VTW of 1,240.24 ± 407.78 N-cm, a peak IT of 20.26 ± 7.03 N-cm, and an RFA of 73.40 ± 2.33 ISQ. The 25% undersized group showed a mean VTW of 1,254.96 ± 727.49 N-cm, a peak IT of 17.15 ± 10.39 N-cm, and an RFA of 72.30 ± 6.70 ISQ. For VTW, the difference between the standard and undersized protocol values was statistically significant; for peak IT, the difference between the standard and 10% undersized protocol values was statistically significant; no other statistical differences were found between mean values. Conclusions In the presence of poor-bone quality, a 10% undersized protocol is sufficient to improve the primary stability of the implant; additional decreases do not seem to enhance primary stability values.
ABSTRACT
Objectives: The aims of the present study are to evaluate the primary stability of a sample of 4,135 implants and to investigate the correlations between primary stability and mechanical ...characteristic of the implant and bone density at insertion time.
Material and Methods: The study was conducted from March 2002 to January 2009 at a private practice in Bologna (Italy). Patients were eligible for the study if they needed the insertion of single or multiple implants. Bone density, length, and diameter of each implant were recorded. During surgery for each implant, peak insertion torque (IT) was recorded; the resonance frequency analysis (RFA) values were also collected. Finally, it was recorded whether an implant was lost or removed at an early stage (within 6 months from insertion surgery).
Results: A total of 1,045 consecutive patients were included in the study. A total of 4,135 of implants were inserted. The sample presented 1,184 implants inserted in a postextractive site. The mean peak IT was 34.82 ± 19.36. The mean RFA was 71.57 ± 10.63 implant stability quotient. Spearman correlation analysis shows the presence of a weak positive correlation between IT and RFA. The statistical analysis shows a relevant dependency between IT and bone quality and a very weak dependency between RFA and bone quality. Again, the statistical analysis shows a quite weak correlation between length or diameter and IT, but it shows a relevant correlation between length and RFA. Postextractive implants presented a higher mean IT and a lower RFA compared with implants inserted in healed sites. Twenty‐eight (0.7%) implants were considered to have failed and removed within 6 months.
Conclusions: The results show that the implants studied obtain a good primary stability with a standard protocol. The IT and RFA appear as two independent features of primary stability. Data show that only IT is influenced by bone density as well as only RFA is correlated to the length of implants used. Finally, it is possible to obtain a good primary stability also in postextractive sites.
Background: Narrow diameter implants (NDIs; diameter <3.75 mm) are a potential solution for specific clinical situations such as reduced interradicular bone, thin alveolar crest, and replacement of ...teeth with small cervical diameter. NDIs have been available in clinical practice since the 1990s, but only a few studies have analyzed their clinical outcome.
Methods: From November 1996 to February 2004, 237 patients were selected, and 510 NDIs were inserted. Implant diameter ranged from 3.0 to 3.5 mm, multiple implant systems were used, and 255 implants were restored immediately without loading (IRWL). No statistical differences were detected among the studied variables. Consequently, marginal bone loss (MBL) was considered an indicator of the success rate (SCR) to evaluate the effect of several host‐, surgery‐, and implant‐related factors. A general linear model (GLM) was used to detect those variables statistically associated with MBL.
Results: Only three of 510 implants were lost (survival rate SRR = 99.4%), and no differences were detected among the studied variables. On the contrary, the GLM showed that delayed loading and longer (>13 mm) and larger (3.4 and 3.5 mm) NDIs reduced MBL.
Conclusions: NDIs have a high SRR and SCR, similar to those reported in previous studies of regular diameter implants. Moreover, IRWL of NDIs is a reliable procedure, although a slightly higher bone resorption is reported compared to delayed loading. No implant fractures were detected in the present series.
Conometric retention has recently been proposed as an alternative to cement- or screw-retention 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.
Background: The aim of the present study in humans was to conduct a comparative immunohistochemical evaluation of vascular endothelial growth factor (VEGF) and nitric oxide synthase (NOS) expression, ...inflammatory infiltrate, proliferative activity expression, and microvessel density (MVD) in peri‐implant soft tissues of titanium and zirconium oxide healing caps.
Methods: Five patients, three men and two women (aged 30 to 66 years; mean: 49 years), participated in this study. All patients received dental implants that were 3.8 mm in diameter and 11 mm in length. All implants were left to heal in a non‐submerged (single‐stage) mode. Healing caps (3.8 mm in diameter and 3.0 mm in height) were inserted in all implants. Half of the implants were supplied with standard, prefabricated caps of commercially pure titanium, whereas the other half were provided with test zirconium oxide caps. After a 6‐month healing period, a gingival biopsy was performed with a circular scalpel (5.5 mm in diameter) around the healing caps of both groups, without unscrewing or removing the healing caps. The dimensions of the gingival biopsies were 1.7 mm (5.5 − 3.8 mm) in thickness and 3 mm in height.
Results: Statistically significant differences were found in the microvessel density between titanium and zirconium oxide healing caps and group II (P ≤0.0001). Statistically significant differences were likewise found in the low and high intensities of NOS1, NOS3, and VEGF (P ≤0.0001). In conclusion, the high intensity of NOS1, NOS3, and VEGF were mostly expressed in the titanium group, whereas the low intensity of NOS1, NOS3, and VEGF were mostly expressed in the zirconium oxide group.
Conclusions: In our specimens, the inflammatory infiltrate was mostly present in the titanium specimens. Their extension was much larger than that of the zirconium oxide specimens. Higher values of MVD were observed in the titanium specimens (29.1 versus 15.8). In addition, a higher expression of VEGF intensity was observed in the peri‐implant tissues of titanium healing caps, whereas predominantly lower expressions of VEGF intensity were noted around the zirconium oxide healing caps. The Ki‐67 expression was higher in the titanium specimens. All these data revealed that the tissues around titanium healing caps underwent a higher rate of inflammation‐associated processes, most probably correlated to the higher inflammation processes observed in these tissues. A higher intensity expression of NOS1 and NOS3 was recorded in the tissues around titanium, whereas, on the contrary, a lower intensity of expression was found in the tissues around zirconium oxide specimens. These latter data indicate that the higher expression of these two mediators could be correlated to the higher amount of bacteria present around the titanium samples.
Abstract 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(R), 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.
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.
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