lNTRODUCTlON

Adequate bone height and bone width are essential for dental implant placement. In the posterior mandible, alveolar bone volume could be resorbed too severely to accommodate a dental implant due to persistent periodontal disease, early loss of teeth, or prolonged use of removable prostheses[1]. Short dental implants are recommended when the residual bone height (RBH) is more than 6 mm[2,3].Vertical bone augmentation approaches [like onlay bone graft, guided bone regeneration, and distraction osteogenesis][1,4] and inferior alveolar nerve (IAN) reposition[5] are recommended when the RBH is less than 6 mm. However, these approaches are technically challenging and accompanied by complications, such as soft tissue dehiscence, barrier membrane exposure[6], infection, displacement of the transport segment[7], and neurosensory abnormalities[5]. Therefore, a minimally invasive, less risky, and more accurate technique is needed for severe atrophic posterior mandible edentulous patients.

圖9為不同風(fēng)場下輸電塔L1層位移響應(yīng)隨風(fēng)向角的變化，圖中同時給出三個典型風(fēng)速下的結(jié)果。由圖9可見，在風(fēng)向角0°～90°變化過程中，輸電塔x向位移響應(yīng)整體上呈減小趨勢，y向位移響應(yīng)呈增大趨勢；x向約在15°風(fēng)向角、y向約在60°風(fēng)向角分別存在響應(yīng)極值，且風(fēng)速越大，這一特征越顯著。綜合不同風(fēng)向下位移響應(yīng)來看，x向位移響應(yīng)要高于y向位移響應(yīng)，這主要與x向的投影面積較大有關(guān)。從響應(yīng)隨風(fēng)向的變化規(guī)律看，沖擊風(fēng)場與B類風(fēng)場具有一定的相似性。

Computer-assisted dynamic navigation systems (CADNSs) based on cone-beam computed topography (CBCT) navigation have been introduced into the field of dental implantology to improve the accuracy of implant placement and avoid potential complications[8,9]. A CADNS is a surgical navigation system which can design the location of a virtual implant according to CBCT data. In addition, it allows real-time tracking of implant drills in three dimensions (3D) on a monitor[10]. It is significantly predictable, accurate, and less risky than freehand implant surgeries[11]. Therefore, it is suitable for guiding implant insertion surgery in edentulous patients with critical alveolar bone volumes. This article reports a case using CADNS in the posterior mandible with severe bone resorption to avoid IAN injury. This article follows the recommendations of the CARE guidelines[12].

CASE PRESENTATlON

Chief complaints

A 50-year-old woman was referred to our clinic with the chief complaint of loss of posterior mandibular teeth over 5 years. Oral examination showed that teeth 36 and 37 were missing (Figure 1A). Tooth 38 had erupted and was occluded with the upper teeth. The distance between the gingiva and maxillary teeth at the edentulous area was 6-7 mm, while the mesiodistal distance was about 18 mm (Figure 1B).

整個教學(xué)設(shè)計由導(dǎo)入、體驗和歸納三個階段組成。在導(dǎo)入階段，以一部學(xué)生已經(jīng)非常熟悉的電影展開回顧并提問，在這一過程中導(dǎo)入本課主題的概述；在體驗階段，教師將電影內(nèi)容分層次再現(xiàn)，并布置合理的學(xué)習(xí)任務(wù)，要求學(xué)生模仿完成練習(xí)并加以運用；在歸納階段，學(xué)生根據(jù)教師引導(dǎo)，對所學(xué)虛擬語氣的三個基本形態(tài)予以歸納總結(jié)，形成系統(tǒng)知識，進一步提高他們的自學(xué)能力。

History of present illness

The patient reported no systemic diseases.

通過測試、計算9個注水系統(tǒng)效率和注水系統(tǒng)效率存在問題的分析因素，確定了影響吐哈油田注水系統(tǒng)效率有以下六個方面問題，并針對相應(yīng)的注水系統(tǒng)問題提出相應(yīng)的節(jié)能技術(shù)措施。

History of past illness

The final diagnosis of the presented case was Kenney III dentition defect.

Personal and family history

The patient reported no drug allergy, long-term medication family genetic disease, or smoking.

Physical examination

The patient’s temperature was 36.5 °C, heart rate was 84, blood pressure was 87/61 mmHg, without any other pathological signs.

Laboratory examinations

The blood biochemistry analyses were normal.

Imaging examinations

內(nèi)部審計部門和被審計部門是公司的不同部門，這從本質(zhì)上就就形成了內(nèi)部審計根植于服務(wù)企業(yè)的理念當(dāng)中，這必然造成對內(nèi)部審計職能不能夠全面地認識和理解，把維護本公司的利益當(dāng)成是內(nèi)部審計的職責(zé)所在。在本公司與國家利益產(chǎn)生矛盾的時候，傾向于對本公司利益的維護。更有甚者，在審計過程中對本單位的違法違紀行為含糊處理。

FlNAL DlAGNOSlS

The patient had a free previous medical history.

TREATMENT

The vertical bone heights above the IAN at teeth 37 was insufficient for standard-length implant placement. The following treatment options were considered: (1) Short implants, although the shortest implant available was 6 mm, which was not applicable for tooth 37; (2) onlay bone augmentation,although excessive compression would encroach on prosthesis space, and vertical bone augmentation in the posterior area is challenging; (3) IAN reposition, although this approach can lead to neurosensory disturbances and spontaneous mandibular fractures[5]; (4) trans-IAN implant placement guided by a 3D-printed surgical guide, although the upper surface of the 3D guide needs to be 5 mm away from the alveolar ridge, and the full length of the implant drill is 18-22 mm (since the defect site was rather posterior, the surgery would require the patient’s mouth to remain wide open for a long time, which can be challenging for patients); or (5) trans-IAN implant placement guided by a CADNS for tooth 37.

Based on these factors, a trans-IAN implant placement guided by a CADNS was used. Informed consent of the patient was obtained before the surgery.

Preoperative preparation

Clinical and CBCT examination after restoration (Figure 7A) showed that the marginal bone was fine,the soft tissues around the implants were healthy, and the adjacency and occlusion were appropriate.CBCT examination at the 6-month follow-up (Figure 7B) revealed that the marginal bone was stable and that the implants’ osseointegration was healthy, which fulfilled the success criteria stated by Papaspyridakos

[13].

Prosthodontic treatment planning included evaluating the occlusion, placing the prosthesis(Figure 3C), choosing the implants below the crowns (Figure 3D), and arranging proper position, length,diameter, and abutment for each implant. Because of the insufficient bone height above the IAN, a 4.1 mm × 8 mm implant (ITI, BLT) and a straight abutment were planned for tooth 36 (Figure 2B and C). In addition, a 4.1 mm × 10 mm trans-IAN implant (ITI, BLT) on the buccal side and an angled abutment were planned for tooth 37 (Figure 2E and F). Screw-retained united crowns were designed. Then, the treatment plan was imported into the dynamic navigation software.

Dynamic navigation surgery

Routine operation disinfection and local infiltration anesthesia were performed. The Digital-care Implant Surgery Navigation System (Dcarer, Suzhou, China) was used to assist the surgery. The instruments were calibrated for tracking by the dynamic system. A reference plate was firmly fixed on the mandibular anterior teeth using self-curing resin. Next, the geometry of the patient-tracking array relative to the reference plate was also registered into the dynamic system. Afterwards, implant placement was conducted according to the preoperative planning (Figure 4) with the guide of a realtime navigation operation view on the monitor (Figure 5A-C). The reference plate was removed after implants insertion. Cover screws were connected, and the wound was sutured.

Accuracy verification

After 4 mo, second-stage surgery was performed (Figure 6A). A 1.5-mm straight composite abutment was placed at the first molar site, and a 2.5-mm 17°-angled composite abutment was placed at the second molar site (Figure 6B). Restoration was finished with the screw-retained porcelain-fused-metal union crowns (Figures 6C and D).

OUTCOME AND FOLLOW-UP

Postoperative CBCT (Figure 5D-F) showed that safe distances were ensured between implants and the IAN. The implant at tooth 37 was placed through the buccal side of the IAN, and the distance from the IAN to the implant was 1.7 mm (Figure 5F). The preoperative planning and postoperative CBCT images were imported into the navigation software and matched to calculate the deviation. The deviations at teeth 36 and 37 were 0.831 mm and 0.682 mm at the implant shoulders and 0.574 mm and 0.867 mm at the implant tips, respectively. The angular deviations at teeth 36 and 37 were 3.118° and 2.317°,respectively.

A U-shaped fixture was fixed at the edentulous region after filling with polyether impression material(Figure 1C). Subsequently, both jaws and the U-shaped tube were scanned using CBCT (Figure 1D). The volumetric data was converted into Digital Imaging and Communications in Medicine (DICOM) format.Surface images of dentition and occlusion were obtained by an intraoral optical scanner and were converted to standard tessellation language (STL) format. Both the DICOM and STL files were uploaded into the treatment planning software. The software superimposed the 3D files, and displayed the jaw,dentition (Figure 3A), soft tissue, the alveolar nerve, and occlusion (Figure 3B) in a common coordinate system as a merged file.

DlSCUSSlON

It is challenging to restore a severely atrophic posterior mandible with dental implants. Short implants and vertical bone augmentation are recommended as the priority options in these cases[14]. IAN reposition is also an alternative option when the RBH is less than 6 mm. However, many complications are associated with these treatment options. In this case, the RBH at tooth 37 was 4.5 mm, while there was sufficient bone volume from the IAN to the buccal cortical bone (8.1 mm). Therefore, a tilted implant was inserted into the buccal side of the IAN with guided dynamic navigation. This technique is recommended for patients with sufficient residual alveolar bone width.

2.產(chǎn)業(yè)結(jié)構(gòu)得到了合理調(diào)整，改變了產(chǎn)品結(jié)構(gòu)單一的現(xiàn)狀。不同地區(qū)適合生長和發(fā)展的農(nóng)作物不一樣，有的地方可能不適合生長農(nóng)作物，有的地方雖然適合生長但是由于各種交通和市場條件的限制不適合發(fā)展。通過一系列的政策發(fā)展現(xiàn)代農(nóng)業(yè)，比如丘陵山地地區(qū)不適合發(fā)展農(nóng)作物，但是適合發(fā)展經(jīng)濟作物。所以在這些地方成立專業(yè)的合作發(fā)展經(jīng)濟作物，適當(dāng)發(fā)展小部分的農(nóng)作物，從而改變單一的產(chǎn)品結(jié)構(gòu)。

他的身體如出膛的炮彈，猛地朝著遠處那團紅影射過去。身在空中，六只節(jié)足盤繞擰轉(zhuǎn)，合成了一柄巨大的尖錐。這柄尖錐將盤旋的黑風(fēng)撕開一道豁口，破開前方密密麻麻擁上來的骷髏頭，直射天葬師！

In the past decade, computer-guided implantology techniques have been used widely and play important roles in edentulous patients with severe bone resorption with a favorable accuracy and success rate. Computer-guided implantology technologies include static and dynamic navigation. Both can achieve a satisfactory accuracy in implant surgeries. Block

[15] reported similar accuracies between dynamic and static navigation. Mediavilla Guzmán

[16] reported no significant difference between dynamic and static navigation at the coronal and apical levels, but a significantly smaller angular deviation was observed in the dynamic system. In the present case, the deviations at the implant shoulder of teeth 36 and 37 were 0.831 mm and 0.682 mm, respectively; 0.574 mm and 0.867 mm at the implant apical level, respectively; and angular deviations of 3.118° and 2.317°, respectively. The results were consistent with preliminary studies on the accuracy of dynamic navigation surgeries[8,15,17].

CBCT images showed that the distance from the IAN to the crestal ridge was 9.4 mm, and the distance from the IAN to the buccal cortical bone wall was 5.5 mm at tooth 36 (Figure 2A). The volumes of tooth 37 were 4.5 mm and 8.1 mm, respectively (Figure 2D).

Compared to static navigation, dynamic navigation has many advantages. First, 3D-printed surgical guide plates are not needed, thus reducing expenses and surgical time[18]. Second, no special drills are required. Third, it has a lower requirement regarding an open bite. Fourth, the risk of overheating is decreased due to sufficient irrigation. Finally, it allows for real-time feedback on the preparation and insertion on the implant in 3D[10].

HBV感染診療中，常常選擇HBsAg進行篩查，以HBeAg陽性作為判斷是否存在病毒復(fù)制及具有傳染性的血清學(xué)標志物。但存在乙肝病毒S區(qū)突變［5］或者特殊的血清型(如ay)引起HBsAg漏檢及前C區(qū)啟動子突變導(dǎo)致HBeAg假陰性的現(xiàn)象，因此有必要引入其他的標志物進行補充［6－9］。Pre-S1Ag、Pre-S2Ag、HBV-LP 作為 HBV 表面蛋白的組成成分，參與HBV復(fù)制、感染細胞的識別，并與HBV相關(guān)疾病的進展密切相關(guān)［10－13］，對其檢測可作為HBV感染診斷、HBV復(fù)制監(jiān)測和預(yù)后判斷的有用工具。

Chen LW contributed to treatment planning and manuscript drafting; Zhao ΧE contributed to treatment plan implementation and photo collection; Yan Q contributed to treatment plan implementation and manuscript revision; Χia HB contributed to treatment plan implementation; and Sun Q contributed to manuscript revision and treatment planning.

CONCLUSlON

CADNS can ensure the accuracy and safety of implant placement and avoid the risk of damaging the IAN. Therefore, CADNS-guided trans-IAN placement could be a recommended technique for patients with an extremely insufficient RBH but sufficient buccal bone width in the posterior mandibular area.

在推特上，普通人擁有的潛在影響力不亞于政治人物、官方機構(gòu)和傳統(tǒng)媒體。據(jù)統(tǒng)計，推特上關(guān)注度排名前20的賬號中除去身為政治人物的美國前總統(tǒng)奧巴馬和現(xiàn)總統(tǒng)特朗普，15個是個人賬號，包括演藝明星凱蒂·派瑞、脫口秀主持艾倫·德詹尼斯、足球運動員克里斯蒂亞諾·羅納爾多等，關(guān)注數(shù)均在7400萬以上，遠高于新聞媒體賬號中關(guān)注數(shù)最高的前兩名“CNN突發(fā)新聞”（關(guān)注數(shù)5510萬）和“紐約時報”（關(guān)注數(shù)4231萬）。雖然上述個人均為公眾人物，但反映出個人推特的傳播力絲毫不遜于傳統(tǒng)話語“建制”。

FOOTNOTES

Although a CADNS offers significant advantages, there are some disadvantages. One limitation is the huge initial investment in equipment (CBCT equipment, intraoral scan equipment, and dynamic navigation equipment) and training. Learning to use new software and adapting to virtual imageguided operation may also require effort. Many researchers believe that there is a learning curve to achieve proficiency in this technique. A study showed that dentists become statistically equivalent and proficient after 20 implant placements[15]. As for this case, there is a disadvantage of the CADNSguided trans-IAN technique that it is not always possible to place an implant that provide an ideal prosthetic position.

Clinical New Technology and New Business Project (2021), School and Hospital of Stomatology of Wuhan University.

The patient has given her written informed consent to publish the case (including publication of images).

S P F級T L R 4基因敲除小鼠7 0只，6周齡，（20.3±2.5）g，雄性，購自南京大學(xué)模式動物研究所，合格證號：201800971.普通飼料由湖南中醫(yī)藥大學(xué)動物實驗中心提供，高脂飼料由上海普路騰生物科技有限公司生產(chǎn)提供，動物飼養(yǎng)于湖南中醫(yī)藥大學(xué)實驗動物中心SPF級動物實驗室。實驗過程中，所有研究人員均人道地進行動物實驗，嚴格遵守動物實驗的各項倫理條例。

The authors declare that they have no competing interests.

The authors have read the CARE Checklist (2016), and the manuscript was prepared and revised according to the CARE Checklist (2016).

This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BYNC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is noncommercial. See: https://creativecommons.org/Licenses/by-nc/4.0/

China

Liang-Wen Chen 0000-0001-6455-0368; Χiao-E Zhao 0000-0003-0263-5520; Qi Yan 0000-0002-5809-4199;Hai-Bin Χia 0000-0003-2550-1146; Quan Sun 0000-0003-1475-1692.

Wang JL

A

Wang JL

1 Esposito M, Grusovin MG, Felice P, Karatzopoulos G, Worthington HV, Coulthard P. Interventions for replacing missing teeth: horizontal and vertical bone augmentation techniques for dental implant treatment.

2009 ; CD003607 [PMID: 19821311 DOI: 10 .1002 /14651858 .CD003607 .pub4 ]

2 Jung RE, Al-Nawas B, Araujo M, Avila-Ortiz G, Barter S, Brodala N, Chappuis V, Chen B, De Souza A, Almeida RF,Fickl S, Finelle G, Ganeles J, Gholami H, Hammerle C, Jensen S, Jokstad A, Katsuyama H, Kleinheinz J, Kunavisarut C,Mardas N, Monje A, Papaspyridakos P, Payer M, Schiegnitz E, Smeets R, Stefanini M, Ten Bruggenkate C, Vazouras K,Weber HP, Weingart D, Windisch P. Group 1 ITI Consensus Report: The influence of implant length and design and medications on clinical and patient-reported outcomes.

2018 ; 29 Suppl 16 : 69 -77 [PMID: 30328189 DOI: 10 .1111 /clr.13342 ]

3 Markose J, Eshwar S, Srinivas S, Jain V. Clinical outcomes of ultrashort sloping shoulder implant design: A survival analysis.

2018 ; 20 : 646 -652 [PMID: 29671933 DOI: 10 .1111 /cid.12608 ]

4 Felice P, Barausse C, Barone A, Zucchelli G, Piattelli M, Pistilli R, Ippolito DR, Simion M. Interpositional Augmentation Technique in the Treatment of Posterior Mandibular Atrophies: A Retrospective Study Comparing 129 Autogenous and Heterologous Bone Blocks with 2 to 7 Years Follow-Up. Int J Periodontics Restorative Dent 2017 ; 37 : 469 -480 [PMID:28609491 DOI: 10 .11607 /prd.2999 ]

5 Vetromilla BM, Moura LB, Sonego CL, Torriani MA, Chagas OL Jr. Complications associated with inferior alveolar nerve repositioning for dental implant placement: a systematic review.

2014 ; 43 : 1360 -1366 [PMID: 25128261 DOI: 10 .1016 /j.ijom.2014 .07 .010 ]

6 Todisco M. Early loading of implants in vertically augmented bone with non-resorbable membranes and deproteinised anorganic bovine bone. An uncontrolled prospective cohort study.

2010 ; 3 : 47 -58 [PMID: 20467598 ]

7 Zhao K, Wang F, Huang W, Wu Y. Clinical Outcomes of Vertical Distraction Osteogenesis for Dental Implantation: A Systematic Review and Meta-Analysis.

2018 ; 33 : 549 -564 [PMID: 29763493 DOI:10 .11607 /jomi.6140 ]

8 Edelmann C, Wetzel M, Knipper A, Luthardt RG, Schnutenhaus S. Accuracy of Computer-Assisted Dynamic Navigation in Implant Placement with a Fully Digital Approach: A Prospective Clinical Trial.

2021 ; 10 [PMID: 33919257 DOI: 10 .3390 /jcm10091808 ]

9 Wei SM, Zhu Y, Wei JΧ, Zhang CN, Shi JY, Lai HC. Accuracy of dynamic navigation in implant surgery: A systematic review and meta-analysis.

2021 ; 32 : 383 -393 [PMID: 33540465 DOI: 10 .1111 /clr.13719 ]

10 Cecchetti F, Di Girolamo M, Ippolito DG, Baggi L. Computer-guided implant surgery: analysis of dynamic navigation systems and digital accuracy.

2020 ; 34 : 9 -17 . DENTAL SUPPLEMENT [PMID: 32618156 ]

11 O'Meara S. Commentary on Vermeulen H, Ubbink DT, Schreuder SM and Lubbers MJ (2007 ) Inter- and intra-observer(dis)agreement among nurses and doctors to classify colour and exudation of open surgical wounds according to the Red-Yellow-Black scheme. Journal of Clinical Nursing16 , 1270 -1277 and Sugama J, Matsui Y, Sanada H, Konya C, Okuwa M and Kitagawa A (2007 ) A study of the efficiency and convenience of an advanced portable wound measurement system(VISITRAK). Journal of Clinical Nursing 16 , 1265 -1269 . J Clin Nurs 2008 ; 17 : 1677 -1679 [PMID: 18482135 DOI:10 .1111 /j.1365 -2702 .2007 .02108 .x]

12 Gagnier JJ, Kienle G, Altman DG, Moher D, Sox H, Riley D; CARE Group. The CARE guidelines: consensus-based clinical case report guideline development.

2013 ; 10 : 381 -390 [PMID: 24237192 DOI:10 .3109 /19390211 .2013 .830679 ]

13 Papaspyridakos P, Chen CJ, Singh M, Weber HP, Gallucci GO. Success criteria in implant dentistry: a systematic review.

2012 ; 91 : 242 -248 [PMID: 22157097 DOI: 10 .1177 /0022034511431252 ]

14 Merli M, Moscatelli M, Pagliaro U, Mariotti G, Merli I, Nieri M. Implant prosthetic rehabilitation in partially edentulous patients with bone atrophy. An umbrella review based on systematic reviews of randomised controlled trials.

2018 ; 11 : 261 -280 [PMID: 30246181 ]

15 Block MS, Emery RW, Lank K, Ryan J. Implant Placement Accuracy Using Dynamic Navigation.

2017 ; 32 : 92 -99 [PMID: 27643585 DOI: 10 .11607 /jomi.5004 ]

16 Mediavilla Guzmán A, Riad Deglow E, Zubizarreta-Macho á, Agustín-Panadero R, Hernández Montero S. Accuracy of Computer-Aided Dynamic Navigation Compared to Computer-Aided Static Navigation for Dental Implant Placement: An In Vitro Study.

2019 ; 8 [PMID: 31810351 DOI: 10 .3390 /jcm8122123 ]

17 Block MS, Emery RW, Cullum DR, Sheikh A. Implant Placement Is More Accurate Using Dynamic Navigation.

2017 ; 75 : 1377 -1386 [PMID: 28384461 DOI: 10 .1016 /j.joms.2017 .02 .026 ]

18 Van Assche N, Vercruyssen M, Coucke W, Teughels W, Jacobs R, Quirynen M. Accuracy of computer-aided implant placement.

2012 ; 23 Suppl 6 : 112 -123 [PMID: 23062136 DOI: 10 .1111 /j.1600 -0501 .2012 .02552 .x]