In Chul Rhyu

The Effect of Internal Versus External Abutment Connection Modes on Crestal Bone Changes Around Dental Implants: A Radiographic Analysis

BACKGROUNDnTo the best of our knowledge, the influence of external versus internal implant-abutment connections on crestal bone remodeling has not been reported. The aim of the present study is to investigate the influence of the abutment connection on peri-implant crestal bone levels (CBLs) using radiographic recordings.nnnMETHODSnRadiographic recordings from 40 single-tooth implants (20 external and 20 internal octagonal connections; one implant/patient) in 40 patients (15 males and 25 females; mean age: 54.3 years) were selected for analyses. The radiographic evaluation included the following: 1) linear bone change (LBC); 2) dimensional change (DC); and 3) angle between the implant and adjacent bone (AIB). Differences in LBC, DC, and AIB between implant placement and 1 year after loading for each system were evaluated using a paired t test. Comparison of LBC, DC, and AIB between systems at 1 year after loading was done using analysis of covariance. The significance level was set at P ≤0.05.nnnRESULTSnRadiographic CBLs (LBCs) were reduced at 1 year after loading compared to those at implant placement to reach statistical significance for the external connection (P = 0.000) but not the internal connection (P = 0.939). CBL changes were significantly greater for the external compared to the internal connection (P = 0.000). Similarly, the DC for the external connection was significantly greater compared to that for the internal connection (P = 0.004).nnnCONCLUSIONnWithin the limitations of this study, the implant-abutment connection technology appears to have a significant impact on peri-implant CBLs, with the external connection paralleled by a significant reduction of CBLs.

Evaluation of single-tooth implants in the second molar region: a 5-year life-table analysis of a retrospective study.

BACKGROUNDnTo our knowledge, no study has evaluated the success or survival rate of single-tooth implants that replaced missing maxillary and mandibular second molars. The purpose of the present study was to evaluate the 1- to 5-year cumulative survival rate (CSR) for single-tooth implants placed in the second molar region and the effects of associated factors.nnnMETHODSnFour hundred eighty-nine patients (298 males and 191 females; age range: 23 to 91 years; mean age: 47 years) who were admitted to the Seoul National University Dental Hospital between March 2003 and July 2008 and treated with single-tooth implants in the second molar region (227 maxillary implants and 294 mandibular implants; total: 521 implants) were included in the study. Thirty-two subjects received two implants each. A 1- to 5-year CSR was calculated using a life-table analysis. A comparison of CSRs between maxillary versus mandibular implants, one-stage versus two-stage implants, short (<or=8.5 mm) versus long (>10 mm) implants, and standard-diameter (<or=4.0 mm) versus wide-diameter (>or=5.0 mm) implants was performed using Wilcoxon (Gehan) statistics. P <0.05 was considered significant.nnnRESULTSnFifteen of the 521 implants were lost between insertion and the follow-up examinations. The 1- to 5-year CSR was 95.1%. There were no statistically significant differences in CSRs between implants placed in maxillas and mandibles (96.3% versus 94.9%, respectively; P = 0.084), one- and two-stage implants (95.6% versus 94.7%, respectively; P = 0.267), short and long implants (100% versus 95.1%, respectively; P = 0.582), and standard- and wide-diameter implants (93.8% versus 96.8%, respectively; P = 0.065).nnnCONCLUSIONSnWithin the limitations of the study, the placement of single-tooth implants in the second molar region was an effective and reliable treatment modality. Also, associated factors such as implant diameter, length, and location (the maxilla versus the mandible) may not have an impact on the long-term success of implants.

In-vivo-induced antigenic determinants of Fusobacterium nucleatum subsp. nucleatum.

Fusobacterium nucleatum plays a pivotal role in dental plaque biofilm formation and is known to be involved in chronic inflammatory systemic disease. However, limited knowledge of F.xa0nucleatum genes expressed in vivo interferes with our understanding of pathogenesis. In this study, we identified F.xa0nucleatum genes induced in vivo using in-vivo-induced antigen technology (IVIAT). Among 30,000 recombinant clones screened, 87 reacted reproducibly with pooled sera from 10 patients with periodontitis. The clones encoded for 32 different proteins, of which 28 could be assigned to their functions, which were categorized in translation, transcription, transport, energy metabolism, cell envelope, cellular process, fatty acid and phospholipid metabolism, transposition, cofactor biosynthesis, amino acid biosynthesis, and DNA replication. Putative virulence factors detected were ABC transporter, butyrate-acetoacetate CoA-transferase, hemin receptor, hemolysin, hemolysin-related protein, LysR family transcriptional regulator, serine protease, and transposase. Analysis of immune responses to the in-vivo-induced (ivi) antigens in five patients demonstrated that most were reactive to these proteins, confirming results with pooled sera. IVIAT-identified F.xa0nucleatum genes in this study may accelerate the elucidation of F.xa0nucleatum-mediated molecular pathogenesis.

Bone reconstruction after surgical treatment of experimental peri‐implantitis defects at a sandblasted/acid‐etched hydroxyapatite‐coated implant: an experimental study in the dog

OBJECTIVESnThe objective of this study was to evaluate bone formation/osseointegration following surgical treatment of experimental peri-implantitis at dental implants with different surface characteristics exposed to ligature-induced breakdown conditions.nnnMETHODSnTen turned (control), 10 sandblasted/acid-etched (SA), and 10 SA/hydroxyapatite nanocoated (HA) implants were installed into the edentulated posterior mandible in five Beagle dogs and allowed to osseointegrate for 12xa0weeks. Ligature-induced breakdown defects were then induced over 23xa0weeks using stainless steel wire ligatures. The ligatures were removed and soft tissues were allowed to heal for 3xa0weeks. Next, exposed implant surfaces were decontaminated followed by guided bone regeneration using a collagen membrane and submerged wound healing. The animals were euthanized for histometric analysis at 12xa0weeks post-surgery.nnnRESULTSnThe radiographic analysis showed vertical bone loss following ligature-induced breakdown without statistically significant differences among implant technologies. The histometric analysis showed significantly enhanced bone formation (height) at SA and SA/HA compared with turned implants (pxa0=xa00.028) following reconstructive surgery. Bone formation area was greater at SA/HA compared with turned implants, however the difference did not reach statistical significance.nnnCONCLUSIONSnWhile ligature-induced defect progression does not appear implant surface dependent in this animal model, bone formation at the decontaminated implant surfaces appears more favourable at SA and SA/HA over turned implants following reconstructive surgery.

Rescue of a periodontally compromised tooth by non-surgical treatment: a case report

Purpose This article describes a case of the successful non-surgical management of a periodontally compromised maxillary premolar. Methods A combination therapy, including root planing, occlusal adjustment, and tooth splinting, was applied. Clinical and radiographic examinations were performed during the 16-month follow-up period. Results All periodontal parameters were improved. There were dramatic decreases (3–6 mm) in the probing pocket depth, tooth mobility, and marginal bone loss. Interestingly, gradual resolution of the periapical radiolucency and alveolar bone regeneration were observed in the radiographs, and the periodontal condition was maintained during the follow-up period. Conclusions Within the limits of this study, these results demonstrate the importance of natural tooth preservation through proper periodontal treatment and occlusal adjustment of the periodontally compromised tooth, which is typically targeted for tooth extraction and dental implantation.