螺纹旋转角度和密度对种植体初期稳定性影响的三维有限元研究

目的利用三维有限元模型研究种植体螺纹的旋转角度和密度对种植体初期稳定性的影响。方法建立即刻负载的5种种植体三维有限元模型（0．8mm、1．6mm和2．4mm螺距单螺纹种植体以及双螺纹和三螺纹种植体），进行垂直和水平加载，分析5种种植体颈部和根部的相对位移。结果在3种不同螺距的单螺纹种植体中，垂直加载时0．8mm螺距单螺纹种植体颈部和根部的综合相对位移最小（分别为1．600μm和1．199μm），2．4mm螺距单螺纹种植体颈部和根部的综合相对位移最大（分别为2．451μm和2．019μm）；在螺纹密度相同、旋转角度不同的3种种植体中，0．8mm螺距单螺纹种植体颈部和根部的综合相对位移最小，三螺纹种植体颈部和根部的综合相对位移最大（分别为1．994μm和1．602μm）；在螺纹旋转角度相同、密度不同的种植体中，双螺纹种植体颈部和根部的综合相对位移（分别为1．913μm和1．495μm）均比1．6mm螺距单螺纹种植体（分别为2．412μm和1．799μm）小，三螺纹种植体颈部和根部的综合相对位移均比2．4mm螺距单螺纹种植体小。结论随着种植体螺纹螺距的增加，种植体对抗垂直载荷的能力减弱；随着种植体螺纹旋转角度的增加，种植体对抗垂直载荷的能力减弱；随着种植体螺纹密度增加，种植体对抗垂直载荷的能力增加。     

Reproducibility of the implant crown aesthetic index--rating aesthetics of single-implant crowns and adjacent soft tissues with regard to observer dental specialization

Aim: The Implant Crown Aesthetic (ICA) Index evaluates the aesthetic outcome of implant-supported single crowns in the anterior zone by awarding nine points for the shape, color, and surface characteristics of the crowns and surrounding soft tissue. The aim of this study was to measure the reproducibility of the ICA Index and assess the influence exerted by the examiner's degree of dental specialization.
Materials and Methods: Ten examiners (two general dentists, two prosthodontists, two oral surgeons, two orthodontists, and two dental technicians) applied the ICA Index to 23 implant-supported single crowns twice at an interval of 4 weeks. The inter- and intra-examiner ratings were analyzed. Cohen's kappa (K) was used to measure the interexaminer reliability of estimations by two appraisers at a significance level of p  < .05.
Results: Within the various parameters, the observer agreement ranged 53 to 81%. All the examiners achieved moderate agreement between the first and second ratings, whereby Cohen's kappa was 0.49 ( p  < .001). The most agreement was obtained by surgeons (K = 0.62, substantial) and the least by orthodontists (K = 0.24, sufficient). The lowest level of agreement with other occupational groups was manifested by the orthodontists (≤44.3%). The ICA Index produced a moderate Cohen's kappa of 0.42 and agreement amounting to 67% between the two ratings within the occupational groups. There was minimum agreement among the occupational groups (Cohen's K = 0.11–0.37, observer agreement: 40.2–66.3%); again, the least agreement was between the orthodontists and others.
Conclusions: The ICA Index resulted in poor to moderate intra- and interexaminer agreement. The validity and reproducibility of the ICA indexing as an objective tool in rating implant aesthetics is questionable.     

下颌后牙区不同骨质内种植体即刻负载的三维有限元分析

目的 采用三维有限元分析探讨种植体在下颌后牙区不同骨质条件下即刻负载的应力分布,以期为即刻负载的应用选择提供参考.方法 建立下颌后牙区654-|种植体及上部牙冠和牙槽骨的即刻负载模型,根据骨皮质和骨松质比例构成不同分为B1(颌骨完全由均质的骨皮质构成)、B2(3 mm厚骨皮质包绕致密骨松质)、B3(1.5 mm厚骨皮质包绕致密骨松质)、B4(1.5 mm厚骨皮质包绕疏松骨松质)4种骨质条件,模拟颊舌向45°、100 N的力在修复体中心集中加载,分析各种植体在不同骨质内的von Mises应力分布.结果 颊舌向加载后von Mises应力主要集中于种植体颈部舌侧骨皮质,由B1至B4种植体4-|颈周骨内应力平均值[分别为(13.17±9.32)、(12.95±9.14)、(15.00±9.44)、(16.81±10.74)N]和种植体5-|颈周骨内应力平均值[分别为(15.51±10.32)、(14.73±8.96)、(16.79±8.40)、(18.34±8.45)N]的改变趋势一致,B3应力明显高于B1、B2,B4应力明显高于B3(P＜0.05).从B1～B4种植体6-|颈周骨内应力平均值[分别为(42.45±25.71)、(41.66±25.29)、(42.70±23.24)、(42.06±23.66)N]随骨质改变不大,但均显著高于相应骨质内4-|、5-|颈周骨内应力(P＜0.05).结论 在本项实验条件下进行即刻负载,种植体周围应力分布不仅受颌骨骨质的影响,种植体的植入位置以及建立合理的咬合同样非常重要.

Abstract：

Objective To assess and compare the peri-implant stress distribution of three posterior implants under immediate loading with 4 different bone qualities using three dimensional (3D) finite element (FE) analysis. Methods A 3D finite element model representing three implants in a portion of mandible at the 654-| region was developed, and three implants received a crown each. Four types of bone qualities (B1,B2, B3 and B4) were designed for the model. Load of 100 N was applied on the occlusal surfaces of the crowns at a 45° angle to the vertical axis of the implants. Results Von Mises stresses in the peri-implant bone of4-| in bone quality from B1 to B4 were ( 13. 17 ± 9. 32), ( 12. 95 ± 9. 14), ( 15. 00 ± 9. 44 ), and(16.81 ±10.74) MPa, and those of 5-| were (15.51 ± 10.32), (14.73 ±8.96), (16.79 ±8.40), and(18. 34 ±8.45) MPa. Stress in bone quality B4 showed the highest value, followed by B3 bone, the loweststress were found in B1 and B2 bone. It was significantly different (P ＜0. 05). However, von Mises stresses in different quality of bone around 6-| [(42.45 ±25.71), (41.66 ±25.29), (42.70 ±23.24), (42.06 ±23.66) MPa] were close to each other, and were as twice or three times as those of 4-| and 5-| , irrespective of different bone qualities. Conclusions The stress distribution around implant under immediate loading was not only affected by different bone qualities, but also by the direction of loading, and the latter may have a greater impact when a severe load delivered.     

Evaluation of soft-tissue alteration around implant-supported single-tooth restoration in the anterior maxilla: the pink esthetic score

Purpose: To evaluate the alterations of soft tissue around a single‐tooth implant in the anterior maxilla with a new defined pink esthetic score (PES) at the time of crown placement and 6 months post‐loading. Material and methods: According to the case inclusion criteria, 29 patients subjected to single‐tooth replacement with ITI implant‐supported restoration in the anterior maxilla were included. Assessments of soft tissue after crown placement (baseline) and at 6 months (follow‐up) were performed by two orthodontists with PES. Results: No statistically significant difference was found between the two observers. PES for the single‐tooth implant varied from 6.90 to 9.55 at 6‐month follow‐up. The scores of the mesial and distal papilla, level of soft‐tissue margin, soft‐tissue contour, soft‐tissue color and soft‐tissue texture increased significantly at follow‐up. The highest percentage of improvement in PES was found in the cases scoring 0–4 at the baseline. Conclusions: The esthetic outcome of soft tissue around the single‐tooth implant had improved significantly at follow‐up compared with baseline according to PES assessment. The results suggested that the potential for significant changes in soft‐tissue levels after restorative therapy needs to be considered for single‐implant therapy in the anterior maxilla.     

Biologic and mechanical stability of single-tooth implants: 4- to 7-year follow-up

Background: Single‐tooth implants have been reported to achieve a high level of surgical and prosthetic success. However, close inspection of the literature reveals a paucity of data on the follow‐up of single‐tooth implants in function for 5 years or more. Since unsplinted implants may be considered to be subject to greater functional stresses, there is a need to report on the long‐term biologic and mechanical integrity of such implant‐supported restorations. Purpose: To report on the long‐term follow‐up of single‐tooth implants, restored and in function for 4 to 7 years. Materials and Methods: Twenty‐seven Astra Tech single‐tooth implants were subject to a clinical audit to evaluate implant and prosthetic success as well as response of both hard and soft tissues over a 1‐ to 4‐year follow‐up. This current report presents data on the biologic and mechanical integrity of 23 of these single‐tooth implants, which have been in function for up to 7 years (mean, 63 mo). Data are provided with respect to implant survival, maintenance of marginal bone levels, soft‐tissue health, and the recording of any adverse events, including prosthetic complications. Results: Only 14 implants in 13 patients were available for review, with no failures for this group of implants. One patient from the original group, who was lost to follow‐up, was known to have suffered an implant failure. Furthermore, in accordance with established criteria, the remaining 13 implants that are not included in this report must at this time also be considered as potential failures. As such, the best‐case scenario would be a 95.6% success rate for the 23 implants included in this review and the worst‐case scenario would be a 60.8% success rate. Mean marginal bone loss measured 0.49 mm mesially and 0.76 mm distally, with a frequency of bone loss of 50%. Soft tissues were clinically healthy. There were few adverse events, with only one case of abutment screw loosening, detected at the 6‐year review. In addition, crown decementation was recorded three times in two patients. Conclusions: It can be concluded that the Astra Tech single‐tooth implant can achieve long‐term biologic and mechanical stability when used to restore single missing teeth, over the long‐term.     

Biologic outcome of single-implant restorations as tooth replacements: a long-term follow-up study

Background: The replacement of a single tooth or several teeth by means of single‐implant restorations is an increasingly used method that needs long‐term validation. Purpose: The goal of this study was to evaluate the outcome of single‐implant restorations by means of fixed restorations and to define the prognosis through marginal bone level estimations. Materials and Methods: From November 1986 to June 1998, 270 Brånemark implants (215 in the upper jaw) were installed in 219 patients (106 males). Both anterior and posterior sites were involved. Of the 263 single restorations, 28 were placed in private dental offices. The patients were followed until June 1999. Results: Twelve implants failed before or at abutment connection or within 6 months afterward. Only four implants failed later. The cumulative success rates were 93% for the implants and 96.5% for the restorations over a period of 11 years. The marginal bone loss during the first 6 months after abutment connection reached 0.71 mm and then dropped to 0.036 mm annually over a period of 10 years. Conclusions: Single‐implant restorations (Brånemark System) are a reliable treatment with a good long‐term prognosis. Failures were concentrated during the healing period and early loading phase.     

全瓷冠熔附纯钛小基台种植修复体的临床应用

目的采用全瓷冠熔附纯钛小基台的方法制作种植体支持的修复体，并进行临床修复效果评价。方法机械加工制作颈环及轴壁薄的纯钛小基台，计算机辅助制作（computer aided manufacture，CAM）与基台匹配的全瓷冠，通过烧结遮色瓷将全瓷冠熔附于小基台上，获得修复体。对5例患者的6颗缺失牙进行修复，并对修复体进行临床效果评价。结果成功制作全瓷冠熔附纯钛小基台修复体6个。经临床评价，修复体在表面、外形、边缘及色泽等方面在修复时和修复1年后均获得满意的效果。结论全瓷冠熔附纯钛小基台修复体可作为种植义齿美学修复的新选择。     

A Retrospective Comparison of Outcome in Patients Who Received Both Nonsurgical Root Canal Treatment and Single-tooth Implants

Introduction

Currently, no study has compared the outcome of nonsurgical root canal treatment (NSRCT) and single-tooth implants (STIs) provided to the same patient. The purpose of this study was to determine if the survival outcome of the 2 treatment modalities is different.

Long-term clinical outcomes of immediate loading versus non-immediate loading in single-implant restorations: a systematic review and meta-analysis

Dental implant restoration is a predictable treatment option for replacing missing or damaged teeth. Conventional loading requires a prolonged treatment period and second surgical interventions. The aim of this study was to compare the clinical outcomes between immediate and non-immediate (early or conventional) loading in single-implant restorations. A literature search of the PubMed, Embase, Cochrane Library, Web of Science, and ClinicalTrials.gov databases was performed in January 2020. Only randomized clinical trials (RCTs) were included. The overall risk ratios (RRs), mean differences (MDs), and 95% confidence intervals (CIs) were used in the analyses. A total of 10 RCTs reporting on 423 patients were included. There was no significant difference in any of the outcomes of interest between the immediate and non-immediate loading cases: implant failure at the patient level (RR 1.29, 95% CI 0.35 to 4.78, P = 0.71), implant failure at the implant level (RR 1.19, 95% CI 0.40 to 3.51, P = 0.75), marginal bone loss (MD ?0.04, 95% CI ?0.16 to 0.08, P = 0.54). Subgroup analyses showed similar results. Immediate loading had predictable long-term clinical outcomes if the indicated patients were carefully selected. The influences of several technical factors need to be confirmed in additional clinical trials.