Light-Microscopic Evaluation of the Dimensions of Peri-Implant Mucosa Around Immediately Loaded and Submerged Titanium Implants in Monkeys

Contour angle and peri-implant tissue height: Two interrelated features of the implant supracrestal complex

OBJECTIVES

Recent research has suggested the contour of the prosthesis and the vertical height of the peri-implant mucosa as important parameters that can influence the long term health and stability of the peri-implant tissue. In particular, overcontouring of the prosthesis has been correlated with an increased risk for peri-implantitis, while reduced soft tissue height has been associated with marginal bone loss, recession, and other soft tissue complications. Although these two parameters have been investigated as independent in the current literature, clinical experience points toward a close interrelation between transmucosal tissue height and prosthesis contour angle. It is often found that a reduced vertical height of the implant supracrestal complex is the main reason for overcontouring of the prosthesis. At the same time, achieving a favorable contour of 30o or less is not possible unless the clinician has ensured an adequate vertical height of the soft tissue. The purpose of this short communication is to establish the relation between tissue vertical height and prosthesis contour by utilizing a theoretical geometry equation based on the Pythagorean theorem. In doing so, one can use the dimensions of the implant as well as those of the prosthesis at the mucosal margin to calculate the essential vertical height for achieving a favorable prosthesis contour.

CONCLUSIONS

As the treatment plan of the implant supracrestal complex is "top-down," in case of deficient vertical height, subcrestal placement of the implant should be considered to achieve a proper prosthesis contour.

Peri-implantitis and extracellular matrix antibodies: A case-control study

OBJECTIVE

The aim of this case-control study was to compare patients with a healthy peri-implant environment and patients affected by peri-implantitis, evaluating the occurrence of antibodies to extracellular matrix (ECM) molecules. The authors hypothesized the presence of ECM autoantibodies in serum of peri-implantitis patients.

MATERIALS AND METHODS

Patients were divided into two groups: one with dental implants with a diagnosis of peri-implantitis and one control group with implants classified as being "healthy." Enzyme-linked immunosorbent assay was performed on patients' sera to detect human antibodies to type I, III, IV, and V collagens, laminin, and fibronectin. Fisher exact test was performed to evaluate statistical association, with a significant P < 0.05.

RESULTS

Forty-two patients were enrolled in this study, 27 females (64.28%) and 15 males (35.72%) with a mean age of 53 ± 29.69 years (age range 32-74). The presence of antibodies to CIII was recorded in 6/21 (28.57%) patients of test group, compared to just 2/21 (9.52%) for the control group, showing a statistically significant difference (P < 0.05). Other antibodies tested were found to be not statistically significant or absent.

CONCLUSIONS

Within the limitations of this study, it can be concluded that further studies, with larger sample and different design, are necessary to address the research purpose, evaluating possible associations between anti-ECM antibodies and peri-implantitis.

Use of Porous Implants for the Prosthetic Rehabilitation of Fibula Free Flap Reconstructed Patients

Vascularized free flaps represent today the gold standard in Maxillo-Facial reconstructive treatment of the upper and lower compromised maxillas.The aim of this study is to perform the advantages and disadvantages of the vascularized fibula free flap and the available rehabilitation options with porous implants.In this study the authors analyzed 45 patients with 211 inserted implants treated and reconstructed with vascularized fibula flaps. The authors compared the use of 103 titanium tapered implants (with micro rough surface) versus 108 tantalum-titanium porous implants to evaluate the bone reabsorption and implant survival. Immediate implant stability, the peri-implant reabsorption, and the survival were evaluated. The follow-up was after 3, 6, 12, and 24 months.The authors found that for the 108 Zimmer TM they had an average bone loss of 1 mm ± 0.2 mm after 1 year of follow-up, compared with the other implants where the average bone loss was 2.27 mm ± 0.4.This study demonstrated that the problems caused by different fibula flaps level, compared with the mandibula or, with adjacent teeth in the maxilla, can be solved using TM porous implants that almost duplicate the fixture surface and guarantees long life prognosis to the authors' prosthetic devices.

Does Peri-Implant Mucosa Have a Prognostic Value?

The need for keratinized tissue around implants remains a controversial topic. However, reconstruction of keratinized mucosa may be needed to facilitate restorative procedures, improve aesthetics, and control plaque during oral hygiene. Free gingival grafts, connective tissue grafts, allogenic/xenograft materials, and apically positioned flaps have been used to augment soft tissue around implants. Four different timing protocols have been explored with regard to soft-tissue augmentation: before and during implant placement, during the second-stage surgery, or after restoration. The timing and technique of soft-tissue augmentation remain controversial and lack support from literature. Long-term clinical studies to establish clear guidelines are warranted.

Dental Implants Placed in Patients with Mechanical Risk Factors: A Long-term Follow-up Retrospective Study

Objectives:

Risk factors in oral implantology are defined as local or systemic conditions that increase failure rates. The purpose of this paper is to evaluate the long-term survival rate of dental implants placed in patients presenting mechanical risk factors.

Materials and Methods:

This retrospective study was conducted only with patients presenting at least one of the following risk factors were included: Bruxism; crown-to-implant (C/I) ratio <0.8; abutment angulation. The overall implant survival was estimated using Kaplan–Meier analyses. Risk factors for implant failure were identified using the Cox proportional hazard regression models.

Results:

Eighty-nine eligible patients were enrolled in this study: They were both male (n = 56, 62.92%) and female (n = 33, 37.08%), with an average age of 53.24 (23–76 years), with 227 dental implants inserted. The mean follow-up was 13.6 years (range: 10–16 years). The overall 10-year Kaplan–Meier survival estimate with associated 95% confidence intervals was 86.34% (82.8, 87.1). Bruxism was the only variable that showed a statistically significant association with implant failure (P < 0.05) and a hazard ratio of 2.9, while both Crown to-implant and abutment angulations reported lower values of failure (P > 0.05).

Conclusions:

Within the limitations of this study, can be concluded that data suggested an evident relationship between bruxism and dental implant failure but further studies, with a larger sample and a different design are required to assess this relationship.

Unusual Case of Osseointegrated Dental Implant Migration into Maxillary Sinus Removed 12 Years after Insertion

Displacement of dental implants into the maxillary sinus is not an uncommon event in implant dentistry and may lead to serious complications, such as sinusitis. To avoid systemic problems, performing the removal of the foreign body as soon as possible is suggested. Despite the fact that early implants dislocation has been reported several times, late migration into maxillary sinus has been described by just a few studies. The purpose of this study was to report a rare case of dental implant migration into maxillary sinus after 12 years of function. A 61-year-old woman came to our attention in June 2015 after being visited by an otolaryngologist and being diagnosed with sinusitis and presence of a foreign body into the right maxillary sinus. A panoramic radiograph and a CT scan showed the migration of dental implant sited in 1.6 positions into the maxillary sinus. The implant was removed following a Caldwell-Luc procedure under local anesthesia. Postoperative course was uncomplicated and the patient reported no symptoms of sinusitis after 12 months of follow-up.

Biological width around one- and two-piece implants retrieved from human jaws

Several histologic studies regarding peri-implant soft tissues and biological width around dental implants have been done in animals. However, these findings in human peri-implant soft tissues are very scarce. Therefore, the aim of this case series was to compare the biological width around unloaded one- and two-piece implants retrieved from human jaws. Eight partially edentulous patients received 2 test implants in the posterior mandible: one-piece (solid implants that comprise implant and abutment in one piece) and two-piece (external hexagon with a healing abutment) implants. After 4 months of healing, the implants and surrounding tissue were removed for histologic analysis. The retrieved implants showed healthy peri-implant bone and exhibited early stages of maturation. Marginal bone loss, gaps, and fibrous tissue were not present around retrieved specimens. The biologic width dimension ranged between 2.55 ± 0.16 and 3.26 ± 0.15 to one- and two-piece implants, respectively (P < 0.05). This difference was influenced by the connective tissue attachment, while sulcus depth and epithelial junction presented the same dimension for both groups (P > 0.05). Within the limits of this study, it could be shown that two-piece implants resulted in the thickening of the connective tissue attachment, resulting in the increase of the biological width, when compared to one-piece implants.

Bone-to-implant contact around immediately loaded direct laser metal-forming transitional implants in human posterior maxilla

OBJECTIVE

Direct laser metal forming (DLMF) is a procedure in which a high-power laser beam is directed onto a metal powder bed and programmed to fuse particles according to a computer-aided design file, generating a thin metal layer. This histologic study evaluated the bone-to-implant contact (BIC%) around immediately loaded DLMF transitional implants retrieved after 2 months from posterior human maxillae.

METHODS

Twelve totally edentulous individuals (mean age, 66.14 ± 2.11 years) received DLMF transitional implants divided in twelve immediately loaded (IL) and twelve unloaded (UI) implants. These transitional implants were placed between conventional implants to support the interim complete maxillary denture during the healing period. After 8 weeks, the transitional implants and the surrounding tissue were removed and prepared for histomorphometric analysis.

RESULTS

Mature woven preexisting bone lined by newly formed bone in early stages of maturation were found around all retrieved implants. Histometric evaluation indicated that the mean BIC% was 45.20 ± 7.68% and 34.10 ± 7.85% for IL and UI, respectively (P <0.05).

CONCLUSION

The present data obtained in humans showed that, although both IL and UI presented good BIC%, IL DLMF implants had a higher BIC% in the posterior maxilla.