Simultaneous flapless implant placement and peri-implant defect correction: an experimental pilot study in dogs

BACKGROUND: Minimally invasive implant surgery allows clinicians to place implants in less time, without extensive flaps, and with less bleeding and postoperative discomfort. The purpose of this study was to evaluate a new surgical technique by which implants are inserted in a deficient alveolar ridge using a flapless technique simultaneously with a peri-implant defect correction that is performed using a subperiosteal tunneling procedure. METHODS: Bilateral, horizontal defects of the alveolar ridge were created in the mandibles of five mongrel dogs. After 3 months of healing, one implant was placed on each side of the mandible by a flapless procedure. The exposed threads of the implant on one side of the mandible were covered with a 1:1 autogenous bone/xenograft mixture using a subperiosteal tunneling technique. Four months later, biopsies of the implant sites were taken and prepared for ground sectioning and analysis. RESULTS: All implants were well osseointegrated with the host bone. All of the peri-implant defects at the test sites were covered with tissue that resembled bone. In all specimens, a mixture of bone, connective tissue, and residual bone particles was observed in the graft area. In the control sites, where no graft was used, none of the exposed threads on any implants were covered with new bone. CONCLUSION: This preliminary report indicates the potential use of a minimally invasive flapless technique as a substitute for a more invasive implant placement and ridge augmentation procedure.     

Patient-centred outcomes comparing transmucosal implant placement with an open approach in the maxilla: a prospective, non-randomized pilot study

It was the aim of the study to assess differences in patient morbidity between transmucosal implant placement and implant installation after elevation of mucoperiosteal flaps. In five of the patients, implants were placed in the maxilla transmucosally using a CAD/CAM surgical template [test group (TG)]. In the remaining five patients, the implants were installed after the elevation of mucoperiosteal flaps [control group (CG)]. Directly after surgery, at days 1 and 7 after surgery the patients rated pain and discomfort on a visual analogue scale (0=minimal pain and discomfort, 100=maximal pain and discomfort). Optical three-dimensional images were assessed preoperatively and at days 1 and 7 after surgery to determine the visible soft tissue swelling of the upper lip and cheeks. Directly postoperatively, the mean pairwise difference between both groups in view of pain and discomfort ratings (control minus test) was 45.6 (SD, 20.7). At days 1 and 7, the mean differences were 51.6 (SD, 21.8) and 19 (SD, 8), respectively. The overall test of the area under curve (AUC) against the null hypothesis 'AUC of pairwise differences of pain score over study time equals null' yielded a significant difference (P=0.01). The mean pairwise difference between both groups in view of soft tissue volume increase was 6.1 (SD, 2) cm(3) at day 1 after surgery and 4.6 (SD, 1.2) cm(3) at day 7. The overall test of the AUC against the null hypothesis 'AUC of pairwise differences of oedema measurements over study time equals null' yielded a significant difference (P=0.002). Within the limitations of this pilot study, it could be shown that transmucosal implant placement reduces patient morbidity significantly compared with an open approach.     

Immediate transmucosal implant placement: a report of 2 cases

Immediate placement of implants into fresh extraction sockets has the advantages of decreasing the recommended period of healing, reducing the resorption of the alveolar bone, and achieving optimal esthetic results. A high rate of success with immediately placed implants has been reported in the literature. Conventional intervention involves 2 or 3 surgical visits, and this may not be accepted by the patient or may be of some inconvenience. The technique described involves only one surgical visit at which a transmucosal endosseous root-form implant is inserted, followed by application of a resorbable membrane.     

A model study on flapless implant placement by clinicians with a different experience level in implant surgery

INTRODUCTION: Some implant companies advocate that flapless surgery is easy to perform and beneficial for aesthetics and patients morbidity. However, studies objectively analyzing the position in the bone of implants installed with this approach are lacking. This in vitro model study was performed to analyse deviations in position and inclination of implants placed with flapless surgery compared with the ideally planned position and to examine whether the outcome is affected by experience level. METHODS: Identical radio-opaque resin models were developed with a silicon lining mimicking the soft tissues and six edentulous single tooth spaces. Eighteen clinicians (six periodontists, six general dentists and six students) drilled four implant sites each (Straumann AG, Basel, Switzerland) with a flapless approach. Corresponding CT-scan images of the models were available. A virtual implant program (Simplant, Materialise NV, Leuven, Belgium) was used to plan the ideal position and to compare this with the implant angulation and position of the test implants. RESULTS: There were no significant differences between the experience groups for all parameters except for global deviations between dentist and students, angle deviations between dentists and students and horizontal deviations between specialists and students. In incisor sites, specialists and students deviated significantly more in global deviation and depth than dentists. In premolar and molar sites, there were no significant differences except for horizontal deviations between specialists and dentists in molar sites. As a consequence of the malpositioning, perforations were seen in 59.7% (43/72) of the implant occasions when the artificial mucosa was removed from the model. CONCLUSION: The three-dimensional location of implants installed with flapless approach differs significantly from the ideal, although neighbouring teeth were present and maximal radiographical information was available. Within the limitations of this in vitro model study it seems necessary to point out that these deviations would in a clinical situation lead to complications such as loss of implant stability, aesthetical and phonetical consequences. The outcome is not influenced by the level of experience with implant surgery. This points out that more precise measurements of soft tissue in situ or additional use of guiding systems are recommendable.     

Immediate transmucosal implant placement in molar extraction sites: a 12-month prospective multicenter cohort study

Aim: To assess the clinical and radiographic outcomes of immediate transmucosal placement of implants into molar extraction sockets. Study design: Twelve‐month multicenter prospective cohort study. Material and methods: Following molar extraction, tapered implants with an endosseous diameter of 4.8 mm and a shoulder diameter of 6.5 mm were immediately placed into the sockets. Molars with evidence of acute periapical pathology were excluded. After implant placement and achievement of primary stability, flaps were repositioned and sutured allowing a non‐submerged, transmucosal healing. Peri‐implant marginal defects were treated according to the principles of guided bone regeneration (GBR) by means of deproteinized bovine bone mineral particles in conjunction with a bioresrobable collagen membrane. Standardized radiographs were obtained at baseline and 12 months thereafter. Changes in depth and width of the distance from the implant shoulder (IS) and from the alveolar crest (AC) to the bottom of the defect (BD) were assessed. Results: Eighty‐two patients (42 males and 40 females) were enrolled and followed for 12 months. They contributed with 82 tapered implants. Extraction sites displayed sufficient residual bone volume to allow primary stability of all implants. Sixty‐four percent of the implants were placed in the areas of 36 and 46. GBR was used in conjunction with the placement of all implants. No post‐surgical complications were observed. All implants healed uneventfully yielding a survival rate of 100% and healthy soft tissue conditions after 12 months. Radiographically, statistically significant changes (P<0.0001) in mesial and distal crestal bone levels were observed from baseline to the 12‐month follow‐up. Conclusions: The findings of this 12‐month prospective cohort study showed that immediate transmucosal implant placement represented a predictable treatment option for the replacement of mandibular and maxillary molars lost due to reasons other than periodontitis including vertical root fractures, endodontic failures and caries.     

Zygomatic implant placement using a robot-assisted flapless protocol: proof of concept

Robotic assistance can help in physically guiding the drilling trajectory during zygomatic implant positioning. A new robot-assisted strategy for a flapless zygomatic implant placement protocol is reported here. In this protocol, a preoperative computed tomography scan is used to plan the surgical path. After surface registration, the ROSA robot (Zimmer Biomet Robotics) guides several steps, which are performed with shared control. The surgeon performs the drilling and tapping, guided by the robotic arm, which is positioned according to the planned trajectory. Placement of the zygomatic implant is done manually. Immediate intraoperative 3D verification is performed by cone beam computed tomography (flat-panel detector, Medtronic O-arm II). Four zygomatic implants were placed in the case patient according to the flapless protocol, with a mean vector error of 1.78 mm (range 0.52–4.70 mm). A screw-retained temporary prosthesis was placed on the same day. No significant complications were observed. The application of this robot-assisted surgical protocol, which guarantees a very high degree of precision, may reduce inaccuracies in the positioning of zygomatic implants that could deviate from the surgeon’s plan. This appears to be a potentially safe flapless surgery technique. Drill slipping on the crest or on the maxillary wall is the main source of error in this procedure, emphasizing the usefulness of the assisted surgical guidance with haptic feedback.     

Simplistic partially limiting surgical guide for flapless implant placement: a case report

The accurate positioning of implant in bone is important in order to meet the biological, esthetic, and biomechanical requirements of the prosthesis. This becomes crucial in flapless implant placement. The combination of bone sounding and use of a surgical guide will allow precise placement of a dental implant, abutment, and provisional restoration in a minimally invasive manner. A technique to transfer the diagnostic information to the surgical guide is described in this report. The chief advantage of the procedure is the ability to apply flapless implant placement surgery and immediate loading.     

Comparison between flapless and open-flap implant placement: a systematic review and meta-analysis

No consensus has been reached regarding the influence of the flapless and open-flap surgical techniques on the placement of dental implants. This systematic review compared the effects of flapless implant placement and implant placement with elevation of the mucoperiosteal flap in terms of marginal bone loss, implant survival rate and complications rates. This review followed PRISMA guidelines and was registered in PROSPERO with the registration number CRD42017071475. Two independent reviewers performed a comprehensive search of the PubMed/MEDLINE, Scopus, and Cochrane Library databases for studies published until December 2017. The search identified 559 references. After a detailed review, 24 studies were assessed for eligibility. A total of 1025 patients who had received a total of 1873 dental implants were included. There were no significant differences between the flapless and open-flap surgical techniques in terms of implant survival rates (P = 0.34; risk ratio (RR): 1.36; confidence interval (CI): 0.72–2.56), marginal bone loss (P = 0.23; MD: −0.20; CI: −0.52–0.13), or complication rates (P = 0.67; RR: 1.10; CI: 0.70–1.73). The current meta-analysis showed that the implant survival rate, marginal bone levels, and complications of flapless surgery were similar to those of open-flap surgery over a mean follow-up period of 21.62 months.     

Precision of implant placement with stereolithographic templates: a pilot in vitro study

This pilot study assesses the accuracy of 2 bone-supported stereolithographic surgical templates with respect to placement of implants in originally planned positions, and it tests the precision of dental volumetric tomography planning. Two mandibles retrieved from formalin-fixed human cadavers were scanned by dental volumetric tomography for planning of the implant positions, leading to stereolithographic models and fabrication of surgical guides. The situation immediately following drilling and implant insertion by an experienced surgeon was scanned and the outcome compared with the initial planning. The 3-dimensional discrepancies were then analyzed and determined. The results show deviations of the placed implants from the original planning, especially in the vertical direction, making the seating of a prefabricated denture impossible. At present, the flapless surgery technique based on stereolithographic surgical templates appears unsafe; further improvement is required.     

Computer-assisted flapless implant placement reduces the incidence of surgery-related bacteremia

Objective

Bacteremia—the access of bacterium to the bloodstream—may yield life-threatening complications. The aim of this study was to compare the incidence, duration, and type of bacterium leading to bacteremia with relation to conventional and computer-assisted flapless implant surgery.

Material and methods

A total of 377 implants were placed in 68 edentulous jaws using the conventional (conventional group) or a computer-assisted stereolithographic (SLA) template-guided surgery technique (flapless group). Bacteremia was monitored from pre- and postoperative blood samples.

Results

The duration of the surgical intervention was significantly shorter in the flapless group (p?=?0.3510). Baseline samples were sterile. Following the 15th minute after the placement of the last implant, bacteria were present in 62 and 12 % of the patients in the conventional and flapless groups, respectively (p?<?0.0001; relative risk: 3.05). The differences in the incidence of the bacteremia detected at the baseline and 15 min after the last implant placement were statistically significant in the conventional group (p?=?0.0001). However, no such statistical significance was present in the flapless group. Staphylocccus epidermidis, Bifidobacterium spp., Streptococcus viridans, Corynebacterium spp., and Streptococcus sanguinis were the isolated bacterium.

Conclusions

Irrespective of the utilized technique, bacteremia may occur upon the placement of four to eight implants to an edentulous jaw. The probability of bacteremia for the patients operated with the conventional technique is, however, 3.05 greater than those operated with the flapless technique.

Clinical relevance

Flapless implant placement reduces the incidence of surgery-related bacteremia and, therefore, may be beneficial to patients at risk.     

Risk assessment of inferior alveolar nerve injury for immediate implant placement in the posterior mandible: A virtual implant placement study

Objectives

To investigate the prevalence and morphological parameters of lingual concavity, and whether these factors are related to a higher risk of inferior alveolar nerve (IAN) injury when performing an immediate implant surgery in posterior mandible region.

Methods

The CBCT images from 237 subjects (1008 teeth) were analysed the shape of the mandibles (C, P, U type), dimensional parameters of lingual concavity (angle, height, depth), and its relation to inferior alveolar canal (IAC) (A, B, C zone), RAC (distance from root apex to IAC) and probability of IAN injury. Multiple logistic regression modelling to determine the odds ratio of variables that made an important contribution to the probability of IAN injury and to adjust for confounding variables.

Results

The U type ridge (46.7%) and the most concave point located at C zone (48.8%) are most prevalent in this region. The mandibular second molar presents highest risk for IAN injury than other tooth type (p < 0.001), which were 3.82 times to occur IAN injury than the mandibular second premolar. The concave point located at A zone and B zone were 7.82 and 3.52 times than C zone to have IAN damage, respectively. The probability of IAN injury will reduce 26% for every 1 mm increase in RAC (p < 0.001).

Conclusions

The tooth type, morphological features of lingual concavities, and RAC are associated with risks of IAN injury during immediate implant placement.

Clinical significance

Pre-surgical mapping of the IAC and identification of its proximity relative to the lingual concavity in the posterior mandible regions may avoid unpleasant complications, specifically when performing immediate implant procedures.     

上颌单颗前牙不翻瓣即刻种植的临床应用研究

目的：研究上颌单颗前牙不翻瓣即刻种植的短期临床效果。方法：17例上颌单颗前牙微创拔除后不翻瓣即刻植入种植体,经软组织塑形后,完成最终上部结构。随访3-9个月,对种植体周围软硬组织进行评价。结果：17例种植体均获得良好骨结合,种植体无松动脱落。种植体周围软硬组织状态良好,美学效果满意。结论：上颌单颗前牙不翻瓣即刻种植短期内可获得较满意的临床效果。     

下颌磨牙即刻种植临床探讨

目的：介绍一种简单易行的下颌磨牙即刻种植方法并对其临床效果进行评估。方法：20颗下颌磨牙经微创拔牙后,不翻瓣植入特定形状的种植体和愈合基台,无须植入人工骨或覆盖胶原膜,种植体采用穿龈愈合方式。种植体植入3个月后常规印模,完成上部结构修复。种植体完成修复后随访3-24月。结果：所有的种植体均获得良好的骨结合,种植体周软硬组织保持完好,美学效果令人满意。随访期内所有种植牙正常行使功能。结论：下颌磨牙不翻瓣即刻种植方法简单易行,临床效果可靠,减少了手术次数,缩短了治疗时间,降低了治疗费用,值得临床推广。     

Ridge alterations following immediate implant placement in the dog: flap versus flapless surgery

Objective: To assess the healing process after flap or flapless surgery in immediate implant placement.
Material and Methods: This study was carried out on five Beagle dogs. Four implants were placed in the lower jaw in each dog immediately after tooth extraction. Flap surgery was performed before the extraction on one side (control), and flapless on the contrary (test). After 3 months of healing, the dogs were sacrificed and prepared for histological analysis.
Results: Ten implants were placed in each group. Two failed (one of each group). The percentage of bone–implant contact was very similar in both groups: 64.8% and 65.1% for the flap and the flapless group, respectively. The difference between the mean distance from the peri-implant mucosa margin to the first bone–implant contact at the buccal aspect was statistically significant between both groups (3.02 mm. flapless and 3.69 mm. flap group). The mean first bone–implant contact at the buccal aspect was located in relation to the sand-blasted and acid-etched level at 0.82 mm for the flapless group and 1.33 mm for the flap group. This difference was not statistically significant.
Conclusion: Flapless immediate implant surgery produces a significant reduction in the vestibular biologic width and a minor reduction in buccal bone plate resorption.     

Erbium:YAG laser application in the second phase of implant surgery: a pilot study in 20 patients

PURPOSE: Conventional implant dentistry implies 2 surgical stages. In this context, pain is often present in the second stage, despite the fact that it is comparatively less aggressive for the patient. The present pilot study proposes application of Erbium:YAG (Er:YAG) laser for second-stage implant surgery. MATERIALS AND METHODS: Twenty patients were studied with a total of 50 implants in which osseointegration was complete. The subjects were divided into 2 groups: a control group (10 patients with 25 implants), subjected to conventional second-stage surgery; and a group of 10 subjects (also with 25 implants) treated with the Er:YAG laser at second-stage implant surgery. RESULTS: The use of Er:YAG laser obviated the need for local anesthesia and minimized postoperative pain and time needed before starting the second stage. With regard to surgical duration, quality of hemostasis, and success in implant treatment, no differences were reported. DISCUSSION: In the second stage of implant surgery, different types of laser have been used, taking advantage of their bacteridal effect; disadvantages arise from inducing damage to the implant surface and adverse thermal effects. CONCLUSION: The advantages afforded by laser treatment include technical simplicity, the possibility of obviating local anesthesia, absence of postoperative pain and edema, and complete tissue healing by day 5, thus facilitating rapid prosthetic rehabilitation. The technique described can be used in all cases except situations where esthetic considerations prevail in anterior areas, or in the event of a lack of keratinized gingiva surrounding the implant.     

Optimized placement of angled abutments for external-hex implant platforms: a pilot study

A survey demonstrated that angled abutments for external-hex implant platforms are difficult to place because of the handling of the components and screwdriver. The purpose of this study was to evaluate the performance of a device facilitating the placement of prefabricated angled abutments. This new instrument features improved ergonomics and is based on the design of a modified pickup impression coping. Forty experienced professionals tested two methods of placing angled abutments in a typodont on implants replacing a maxillary central incisor and a maxillary first molar. Using the new device, the abutments could be placed with a 43.9% reduction in time compared to the original manufacturer's instrument.