Epithelial and Connective Tissue Sealing around Titanium Implants with Various Typical Surface Finishes

Abstract

Soft tissue barrier around a dental implant plays a crucial role in the success of dental implants because it protects underlying hard tissue structures. A number of surface alteration procedures of implants have been introduced to improve bone−implant contact, but there has been little research on the peri-implant soft tissue (PIS) seal. The present study focuses on the "biologic width" of epithelial and connective tissue seals around implants with various typical surface finishes by testing surfaces that have been machined (Ms), roughened by sandblasting and acid etching (Rs), treated hydrothermally with CaCl 2 (Cs), or anodized (As). Ms, Rs, and As techniques are commonly used to finish surfaces of commercially available dental implants. The Cs technique was reported to produce strong epithelial cell−titanium adhesion. For culture study, rat oral epithelial cells (OECs) and fibroblasts were cultured on Ms, Rs, Cs, and As titanium plates. There was less cell adherence of OECs and more collagen expression when cultured on Rs and As plates than when cultured on Ms and Cs plates. For the in vivo study, implants with Ms, Rs, Cs, and As surfaces were placed in the rats' oral cavity. Although the PIS structure was similar to that around natural teeth, a horseradish peroxide assay revealed that the sealing ability around the Ms and Rs implants was weaker than that around Cs implants. After 16 weeks, Rs implants exhibited peri-implant epithelial apical down-growth and had lost bone support. Thus, although a smooth surface (Ms and Cs) showed better epithelial attachment, rough surfaces (Rs and As) are more suitable for binding to the connective tissue. Strong epithelium−implant attachment seems to be a fundamental defense against foreign body penetration. Selecting suitable surfaces to ensure strong sealing is important for implant success.

Localization of Integrin Beta-4 Subunit at Soft Tissue–Titanium or Zirconia Interface

“…In our animal study, there was no statistically significant difference in the length of the Inβ4-positive band between Ti and zirconia groups, both of which were significantly shorter than that for teeth. As previously reported, the length of the laminin-332-postive band on the substratum side of the attachment structure was significantly shorter around Ti than that around teeth [ 7 , 11 ]. The present study showed that the localization of Inβ4 on the cell side of the attachment structure was similar to that of laminin-332.…”

“…The attachment structure between the gingival epithelium and substrata such as enamel or implants comprises two components, namely basal lamina and cell-adhesion protein. Previous studies indicated that the length of the band of laminin-332, which is a main component of basal lamina, is shorter around Ti implants than around the enamel [ 7 , 11 ]. In contrast, another component of the attachment structure, transmembrane receptors in epithelial cells, has not yet been studied in detail.…”

“…The experiment protocol was previously reported [ 11 ]. In brief, 6-week-old Wistar rats (20 males; 120–150 g) underwent extraction of maxillary right first molars under systemic anesthesia.…”

“…The oral mucosa was removed from the maxillary bone, and sections were cut on the coronal plane using a cryostat (−20 °C) after demineralization using a 5% ethylenediaminetetraacetate solution. For immunohistochemical staining, these sections were incubated with rabbit anti-Inβ4 (1:100 dilution, Chemicon International, Billerica, MA, USA) and biotinylated anti-rabbit IgG (1:100 dilution, Sigma-Aldrich, St. Louis, MO, USA), and the presence of Inβ4 was visualized using a diaminobenzidine (DAB) staining kit (Vector Laboratories, Burlingame, CA, USA), as described in a previous paper [ 11 ]. In the present study, the vertical distance between the top of the PIE or JE and the bottom of the Inβ4-positive area was measured in a direction parallel to the implant or natural tooth (Nt) surface.…”

“…The surface roughness value (Ra) of each plate was identical to the implant surface for the animal study. Oral epithelial cells (OECs) were obtained from the oral mucosa of 4-day-old Wistar rats as reported previously [ 11 , 12 , 13 ]. Briefly, oral mucosa were incubated with dispase (1 × 10 3 IU/mL) in Mg 2+ - and Ca 2+ -free Dulbecco’s phosphate-buffered saline for 12 h at 4 °C and removed from the connective tissue layer.…”