Influence of Metal Guide Sleeves on the Accuracy and Precision of Dental Implant Placement Using Guided Implant Surgery: An In Vitro Study

Purpose

Metal sleeves are commonly used in implant guides for guided surgery. Cost and sleeve specification limit the applications. This in vitro study examined the differences in the implant position deviations produced by a digitally designed surgical guide with no metal sleeve in comparison to a conventional one with a metal sleeve.

Materials and Methods

The experiment was conducted in two steps for each step: n = 20 casts total, 10 casts each group; Step 1 to examine one guide from each group with ten implant placements in a dental cast, and Step 2 to examine one guide to one cast. Implant placement was performed using a guided surgical protocol. Postoperative cone-beam computed tomography images were made and were superimposed onto the treatment-planning images. The implant horizontal and angulation deviations from the planned position were measured and analyzed using t-test and F-test (p = 0.05).

Results

For Step 1 and 2, respectively, implant deviations for the surgical guide with sleeve were –0.3 ±0.17 mm and 0.15 ±0.23 mm mesially, 0.60 ±1.69 mm, and –1.50 ±0.99 mm buccolingual at the apex, 0.20 ±0.47 mm and –0.60 ±0.27 mm buccolingual at the cervical, and 2.73° ±4.80° and –1.49° ±2.91° in the buccolingual angulation. For Step 1 and 2, respectively, the implant deviations for the surgical guide without sleeve were –0.17 ±0.14 mm and –0.06 ±0.07 mm mesially, 0.35 ±1.04 mm and –1.619 ±1.03 mm buccolingual at the apex, 0.10 ±0.27 mm and –0.62 ±0.27 mm buccolingual at the cervical, and 1.73° ±3.66° and –1.64° ±2.26° in the buccolingual angulation. No statistically significant differences were found in any group except for mesial deviation of the Step 2 group (F-test, p < 0.001).

Conclusions

A digitally designed surgical guide with no metal sleeve demonstrates similar accuracy but higher precision compared to a surgical guide with a metal sleeve. Metal sleeves may not be required for guided surgery.     

Maintenance of Implant Hybrid Prostheses: Clinical and Laboratory Procedures

Fixed implant hybrid prostheses have been used for the last 40+ years in the treatment of edentulous patients. These prostheses have provided long‐term masticatory function for thousands of patients. The original treatment protocol included fabrication of cast metal frameworks that fit accurately on the restorative platforms or abutments and/or endosseous implants. Frameworks were designed to splint implants together; they also provided retention and support for the functional and esthetic portions of the fixed hybrid prostheses. Initially, edentulous patients were treated with maxillary complete dentures and mandibular fixed, hybrid prostheses. Denture teeth were used in both prostheses. Over the span of many years, occlusal surfaces of the denture teeth in the mandibular prostheses exhibited signs of occlusal abrasion and wear, sometimes completely abrading the teeth and denture bases, resulting in framework exposures. Ultimately, this resulted in decreased chewing efficiency and loss of vertical facial height. Patients would then return to clinicians and ask for retreatment. In certain instances, the underlying frameworks would have to be remade. This involved replicating the original series of appointments and significant additional expense to patients and clinicians alike. The protocol presented in this article avoids having to remake the most expensive portion of fixed implant prostheses—the frameworks. The protocol identifies the clinical and laboratory procedures involved in using existing frameworks and replacing preexisting denture bases and denture teeth, with minimal inconvenience to patients.     

无牙下颌固定种植义齿带末端悬臂的应力分析

目的:比较不同悬臂设计下颌种植支持全口义齿的骨及种植体应力分布特点,为临床种植修复提供生物力学分析依据。方法:建立3组下颌6个种植支持全口义齿的三维有限元模型,悬臂分别为3、6、9 mm。在悬臂末端垂直加载100 N的力。结果:种植全口义齿悬臂末端垂直加载时,末端种植体骨应力集中,易发生松动失败;末端种植体及中间种植体颈部应力集中,易发生植入体与基桩连接失败;连梁应力集中在与末端种植体连接处,此处易发生折断。悬臂长度增加骨应力、种植体应力及连梁应力明显增加。结论:悬臂越短越有利于力的均匀分布。6个种植体支持短悬臂修复设计较符合生物力学分布原理。     

In Vitro Assessment of Primary Stability of Straumann® Implant Designs

Background: Primary implant stability (PS) is one of the main factors influencing implant survival rate. Several methods to determine the PS have been used, such as Periotest values (PVs) and resonance frequency analysis (RFA) with implant stability quotient (ISQ) values. Purpose: The aim of this study was to compare different implant designs in regard to PS assessed by Periotest and RFA in vitro. Materials and Methods: A total of 90 implants were placed in freshly slaughtered cow ribs. The implants (Straumann®, Institute Straumann AG, Basel, Switzerland; length 10 mm, ø3.3 mm) had the following three designs: Bone Level (BL, 30 implants), Standard Plus (SP, 30 implants), and Tapered Effect (TE, 30 implants). Before implant placement, the investigator was calibrated for every design according to the manufacturer's instructions. An independent observer, blinded to the study, assessed the accuracy of placement. RFA based on the Osstell device and PVs were performed after abutment connection. One‐way analysis of variance and Tukey's post hoc test were used for statistical evaluation. Results: All implants were mechanically stable. The mean PV for BL was ?4.67(± 1.18), for SP, ?6.07(± 0.94), and for TE, ?6.57(± 0.57). The mean ISQ values were 75.02(± 3.65), 75.98(± 3.00), and 79.83(± 1.85), respectively. The one‐way ANOVA showed significant difference among three implant designs in PV (p < .0001) and for the ISQ between BL/TE or SP/TE implants (p < .0001). In addition, the Tukey's (pair‐wise comparison) test showed significant differences in PV and RFA between the BL/TE (p < .0001). Conclusion: Within the limitations of this study, higher implant stability was found for tapered designed implants.     

Distortion of Three-Unit Implant Frameworks During Casting, Soldering, and Simulated Porcelain Firings

PURPOSE: The aim of this study was to assess distortion inherent in casting, soldering, and simulated porcelain firings of screw-retained, implant-supported three-unit fixed partial dentures (FPDs). MATERIALS AND METHODS: Ten wax patterns were fabricated on a die-stone cast containing two implants, 20 mm apart from center to center. Five specimens were cast in a high-palladium alloy, exposed to simulated porcelain firings, sectioned, and then soldered with low-fusing solder. Five specimens were cast, sectioned, soldered with high-fusing solder, and then exposed to simulated porcelain firings. For each specimen, two horizontal and six vertical distances between appropriately scribed reference points were measured with a traveling microscope. Comparisons were made among the various measurements taken after wax-pattern fabrication, casting, high- and low-fusing soldering, and each porcelain firing. Data were analyzed using a repeated-measures factorial ANOVA (alpha = 0.05). RESULTS: Significant difference was detected in the amount of horizontal distortion during casting (53 +/- 24 microns) and high-fusing soldering (-49 +/- 50 microns), as well as in the amount of horizontal distortion during high-fusing soldering (-49 +/- 50 microns) and low-fusing soldering (17 +/- 26 microns). However, no clinically significant difference was found in the amount of horizontal distortion during casting, low-fusing, and high-fusing soldering. The greatest amount of distortion during the simulated porcelain firings took place during the oxidizing cycle. CONCLUSIONS: Soldering did not improve the casting misfit of a three-unit implant-retained FPD model. Metal-ceramic implant frameworks should be oxidized before intraoral fit evaluation.     

Three‐Dimensional Accuracy of Guided Implant Placement: Indirect Assessment of Clinical Outcomes

Purpose: Precise preoperative implant planning and its exact intraoperative transfer are crucial for successful implant‐supported rehabilitation of partially or completely edentulous patients. In the present pilot study, optical laser scanning was used to evaluate deviations between three‐dimensonal computer‐assisted planned and actual implant positions by indirect methods. Material and Methods: Five patients receiving a total of 15 implants were included in this study. The used planning software was SimPlant 12.0 (Materialise Dental, Leuven, Belgium) to visualize the implant positions, and with an appropriate guided surgery protocol (Navigator?, Biomet 3i, Palm Beach Gardens, FL, USA) implant positions were implemented via tooth‐supported stereolithografic surgical guides. All implants (Osseotite?, Biomet 3i) were inserted in a flapless approach and immediately provided with prefabricated temporary splinted restorations. Intraoral pickup impressions were taken postoperatively, and the implant positions of the master casts were compared with presurgical casts. Implant replica deviations were evaluated by three‐dimensional optical laser scanning providing distances and angulations between implant replicas. Results: Overall, the postsurgical implant replica positions were found to deviate from the positions in the preoperative cast by a mean of 0.46 ± 0.21 mm (range: 0.09–0.85 mm). Positional deviations were 0.27 ± 0.19 mm (range: 0.04–0.60 mm) along the x‐axis representing the buccal‐lingual directions, 0.15 ± 0.13 mm (range: 0.0–0.34 mm) along the y‐axis representing the ventrodorsal direction, and 0.28 ± 0.19 mm (range: 0.02–0.59 mm) along the z‐axis representing cranial and apical directions. Rotational deviations amounted to 14.04 ± 11.6° (range: 0.09–36.47°). Conclusions: The results of this pilot study demonstrate precise transfer of implant replica position by means of simulated guided implant insertion into a preoperative cast and a postoperative cast obtained from impressioning. Further studies are needed to identify appropriate evaluation techniques and mechanisms to increase the transfer precision of three‐dimensional planning and guiding systems.     

软组织在炎症状态下对不同基台材料反应的组织学观察

目的:比较种植体周围软组织对不同基台材料的组织学反应。方法:构建钛和氧化锆愈合基台修复的犬动物模型,并构建种植体周围黏膜炎模型,采集临床牙周指标:菌斑指数、牙龈指数和探诊深度,并对种植体周围的软组织进行采样,对其中的炎性细胞进行免疫组化染色观察和分析。结果:钛和氧化锆愈合基台周围的牙周指标相似,愈合基台周围软组织中的炎性细胞主要位于基底层、靠近愈合基台的软组织和附近的小血管,两种愈合基台周围在炎性状态下的炎性细胞浸润相似。结论:种植体周围的软组织在炎症状态下对钛和氧化锆基台的组织学反应相似。     

牙种植体即刻负重临床疗效观察

目的：种植体即刻负重技术有益于缩短种植手术与修复的“等待期”,及时满足美观和咀嚼要求,进一步扩大种植义齿临床适应证。本文旨在探讨该技术的适应证、操作技巧,评价其临床疗效。方法：CDIC种植体植入23例牙缺失患者,共植入49枚种植体,术后1周内完成上部结构修复,经检测种植体动度、GI及有无种植体周围炎、口腔全景片等指标,评价临床成功率。结果：随访1-6年,23例患者中,仅1例患者的1枚种植体松动、脱落,其余种植体均获临床成功,临床成功率为98％。结论：即刻负重修复患者应为牙槽嵴丰满之中青年患者．种植体周围应有足够的骨壁包绕,以增加初期稳定性。从黏骨膜瓣环切至种植体窝洞预备,都应贯彻“宁小勿大”原则,增加种植体的嵌合能力。一期法、非翻瓣式手术有利于软组织愈合,减少种植体周围炎发生几率：前牙即刻负重修复时,多枚种植体的连冠（T-T）修复优于单枚种植体修复,后牙即刻负重适用于2颗以上的种植体支持式固定修复,以分散[牙合]力,增加稳定性。     

A Hydrophilic Dental Implant Surface Exhibit Thrombogenic Properties In Vitro

Background: Surface modifications of dental implants have gained attention during several years and the thrombotic response from blood components with these materials has become more important during recent years. Purpose: The aims of this study were to evaluate the thrombogenic response of whole blood, in contact with clinically used dental surfaces, Sandblasted Large grit Acid etched titanium (SLA) and Sandblasted Large grit Acid etched, and chemically modified titanium with hydrophilic properties (SLActive). Methods: An in vitro slide chamber model, furnished with heparin, was used in which whole blood came in contact with slides of the test surfaces. After incubation (60‐minute rotation at 22 rpm in a 37°C water bath), blood was mixed with ethylenediaminetetraacetic acid (EDTA) or citrate, further centrifuged at +4°C. Finally, plasma was collected pending analysis. Results: Whole blood in contact with surfaces resulted in significantly higher binding of platelets to the hydrophilic surface, accompanied by a significant increase of contact activation of the coagulation cascade. In addition, the platelet activation showed a similar pattern with a significant elevated release of β‐TG from platelet granule. Conclusions: The conclusion that can be drawn from the results in our study is that the hydrophilic modification seems to augment the thrombogenic properties of titanium with implications for healing into bone of, that is titanium dental implants.