Novel Implant Design Improves Implant Survival in Multirooted Extraction Sites: A Preclinical Pilot Study

• Autores: Adi Sivan-Gildor
• Localización: Journal of periodontology, ISSN 0022-3492, Nº. 10, 2014, págs. 1458-1463
• Idioma: inglés
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• Resumen

  • Background: The primary aim is to evaluate clinical, radiographic, and histologic parameters of novel implants with �three roots� design that were inserted into fresh multirooted extraction sockets. A secondary aim is to compare this new implant to standard root-form dental implants.

    Methods: Immediate implantation of novel or standard design 6 × 6-mm implants was performed bilaterally into multirooted sockets in mandibles of mini-pigs. Twelve weeks later, clinical, radiographic, stability, histomorphometric, and microcomputed tomography (micro-CT) analyses were performed.

    Results: Survival rates were significantly higher in the test implants compared with control (92.8% versus 33.3%, respectively; P <0.001). Bone loss was greater in the control compared with the test by sounding (mean 3.42 ± 0.68 versus 1.96 ± 0.34 mm) and radiography (mean 3.35 ± 0.62 versus 2.27 ± 0.33 mm). Histologic and micro-CT analyses demonstrated bone fill in the inner part of the test implants. Moreover, bone-to-implant contact was higher in the test implants (55.50% ± 3.68% versus 42.47% ± 9.89%). Contrary to the clinical, radiographic, and histomorphometric results, resonance frequency analysis measurements were greater in the control group (77.74 ± 3.21 implant stability quotient [ISQ]) compared with the test group (31.09 ± 0.28 ISQ), P = 0.008.

    Conclusions: The novel design implants resulted in significantly greater survival rate in multirooted extraction sites. Further studies will be required to validate these findings.

    Dental implants have become a widely accepted treatment option for a variety of cases of missing teeth. Currently, >1,300 types of dental implants are available for clinical use; they feature different materials, shapes, lengths, widths, and surface characteristics.1 A review paper found that there is not enough scientific evidence to demonstrate superiority of any particular type of implant; on the other hand, the randomized clinical trials (RCTs) in that review had a �high risk of bias.�1,2 Although some changes in the macro-geometry of implants have been made, research has focused mainly on surface modification.2,3 Whereas implant survival rates reach almost 100%, current research is looking to shorten healing time and improve esthetics.

    In 2006, Esposito et al.4 published a classification of timing of implant placement after tooth extraction: 1) immediately (e.g., at the same time as extraction); 2) immediate-delayed (?8 weeks after extraction); or 3) delayed (>8 weeks after extraction).

    Immediate implant placement has several advantages, including: 1) reduced number of surgical procedures; 2) shorter healing period; 3) improved soft tissue esthetics; and 4) socket orientation for ideal implant placement.5 On the other hand, it has some limitations, including: 1) unpredictable resorption pattern of the alveolar crest; 2) the challenge of achieving primary stability; 3) less soft tissue for primary closure; and 4) local pathology that may compromise healing.6,7 The success rates of immediately placed implants have been studied extensively; systematic reviews and meta-analyses failed to show significant differences between techniques (i.e., immediate versus delayed), a finding that can be related to the heterogeneity of the data and lack of long-term RCTs.8,9 Another problem is that most of the RCTs assessed single-rooted teeth.10-12 RCTs that describe placement of implants immediately into the extraction sockets in the molar area show great diversity in results. In a study by Cafiero et al.13 with 12-month follow-up of immediate implantation in the molar area, a 100% success rate was reported. Another study reported a 94.3% survival rate for immediate implant placement in the maxillary molar area.14 However, in that study, the implants were placed into the palatal-root socket, which mimics a single-rooted socket. Such an approach is likely to compromise the prosthetic results due to palatal deviation of the final restoration and to increase risk for overload. A recent RCT by Atieh et al.15 compared the survival rates of wide implants that were inserted immediately into human molar extraction sockets or into healed molar extraction sites. Overall (delayed and immediate implants), one year survival rates were 75%, however, in the immediate implant group only 66% of the implants survived. The reduced survival rate in this scenario might be associated with reduced primary stability and greater regenerative challenge associated with these large sockets.

    To meet these challenges, a new dental implant was designed specifically to enable higher initial stability and enhanced osseous growth around the implant in molar sites where the socket is wide and or the septum is missing. The three-rooted implant design with its unique hollow space among the three roots was intended to improve initial stability and also allow bone accumulation into the inner part of the implant during implant placement to facilitate osseointegration.

    The primary aim of this study is to evaluate the survival rates, bone height, stability, and bone-to-implant contact (BIC) of this new implant design inserted into fresh multirooted extraction sockets in mandibles of miniature pigs. A secondary aim is to compare this novel implant to standard root-form dental implants with a similar outer diameter.