various surgical techniques have been developed to optimize esthetic outcomes even in operations for malignancy . unlike other parts of the body , thus , it is crucial to minimize postoperative scarring in these areas , especially in neck dissection ( nd ) . robot - assisted and endoscopic - assisted surgeries are typical examples . kang et al.1 first reported robot - assisted modified radical nd in 2010 . they performed the operation via a transaxillary approach , but difficulties in approach to level i , an important area for oral cavity cancer treatment , were encountered2 . to overcome this limitation , nd via modified face - lift or the retroauricular approach using robotic surgery robot - assisted nd has many advantages , such as excellent esthetic outcomes and good visualization during surgery , but its high cost is a problem for most patients . endoscopic - assisted surgery can be an alternative and more cost - effective option compared to robot surgery , as byeon et al.3 recently , we treated two patients who underwent endoscopic - assisted nd via a retroauricular approach and had excellent esthetic outcomes . herein , we report these cases and discuss the pros and cons of endoscopic nd . a 63-year - old male patient visited the department of oral and maxillofacial surgery at dental hospital of yonsei university of college of dentistry in korea . incisional biopsy had been performed by another hospital , which revealed invasive squamous cell carcinoma . the ulcerative lesion was present on the lingual side of # 36 , # 37 and was 3.02.0 cm in size . additional diagnostic imaging , including magnetic resonance imaging ( mri ) and positron - emission tomography ( pet ) , were performed to determine extent of surgery . there was no mandibular or metastatic lymph node invasion , nor were there metastatic lesions on any other organs ( ct2n0m0 , stage ii ) . thus , wide excision with marginal mandibulectomy , selective neck dissection ( snd ) ( i - iii ) via endoscope , and repair of the soft tissue defect with megaderm ( l&c bio , seongnam , korea ) were performed . it took almost 5 hours to complete endoscope - assisted snd ( i - iii ) , with 450 cc of blood loss during the operation . there was mild marginal mandibular branch weakness , which might also have arisen in conventional nd . a 56-year - old male was referred from a local clinic for evaluation of a tongue mass . mri and pet demonstrated no regional or distant metastasis ( ct2n0m0 , stage ii ) . consequently , wide excision with endoscopic nd , reconstruction of the surgical defect with a radial forearm free flap , and repair of the resulting forearm defect with megaderm were performed . it took almost 3.5 hours to complete endoscope - assisted snd ( i - iii ) , with 200 cc of blood loss during the operation . the final diagnosis confirmed the clinical staging ( pt2n0m0 , stage ii ) . unlike in case 1 , no postoperative facial nerve weakness was observed . incision line and anatomical landmarks for endoscpoic neck dissection were outlined on patient 's neck.(fig . 1 ) a retroauricualr incision was used to approach the sternocleidomastoid muscle ( scm ) and a skin flap was created . the scm muscle was exposed , then we continued subplastysmal dissection inferiorly and anteriorly until we reach the omohyoid muscle , hyoid bone and the midline of the neck . during skin flap elevation , a self - retaining retractor ( sejong medical corporation , paju ; sangdosa , seoul , korea ) was used for good visualization of the surgical field . a nerve stimulator was used to identify the marginal mandibular branch of the facial nerve . some portions of level ib , iia , and iii were also dissected under direct visualization . then , a 30-degree endoscope ( 10 mm in diameter , 30 cm in length ; stryker , san jose , ca , usa ) was applied in the level i area followed by fixation with an endoscope holder ( karl storz , tuttlingen , germany).(figs . 2 , 3 ) dissection of the anterior belly area ( level ia ) was performed ; then , level ib , which contains the submandibular gland , was dissected . harmonic curved shears ( harmonic ace 36p ; johnson & johnson medical , cincinnati , oh , usa ) were used to cauterize minor vessels and dissect tissues . the distal facial artery and vein were ligated with premium surgiclips ( covidien , dublin , ireland ) ; the submandibular ganglion , wharton 's duct , proximal facial artery and vein were cut after ligation with surgiclips . we demarcated the level of omohyoid muscle , which is inferior to the border of level iii , and dissected lymphoadipose tissue superiorly from inferior margin using endoscope . finally , dissection of the carotid artery and internal jugular vein was performed with posterior retraction of the scm . micro - vascular surgery was performed in case 2 as usual manuals which have been done in conventional neck dissection.(fig . 4 ) donor vessels such as the proximal portion of facial artery , superior thyroid artery , and related veins were observed well under microscope . . however , an assistant had to retract the skin flap with an army - navy retractor for visualization of the operative field . a 63-year - old male patient visited the department of oral and maxillofacial surgery at dental hospital of yonsei university of college of dentistry in korea . incisional biopsy had been performed by another hospital , which revealed invasive squamous cell carcinoma . the ulcerative lesion was present on the lingual side of # 36 , # 37 and was 3.02.0 cm in size . additional diagnostic imaging , including magnetic resonance imaging ( mri ) and positron - emission tomography ( pet ) , were performed to determine extent of surgery . there was no mandibular or metastatic lymph node invasion , nor were there metastatic lesions on any other organs ( ct2n0m0 , stage ii ) . thus , wide excision with marginal mandibulectomy , selective neck dissection ( snd ) ( i - iii ) via endoscope , and repair of the soft tissue defect with megaderm ( l&c bio , seongnam , korea ) were performed . it took almost 5 hours to complete endoscope - assisted snd ( i - iii ) , with 450 cc of blood loss during the operation . there was mild marginal mandibular branch weakness , which might also have arisen in conventional nd . a 56-year - old male was referred from a local clinic for evaluation of a tongue mass . mri and pet demonstrated no regional or distant metastasis ( ct2n0m0 , stage ii ) . consequently , wide excision with endoscopic nd , reconstruction of the surgical defect with a radial forearm free flap , and repair of the resulting forearm defect with megaderm were performed . it took almost 3.5 hours to complete endoscope - assisted snd ( i - iii ) , with 200 cc of blood loss during the operation . the final diagnosis confirmed the clinical staging ( pt2n0m0 , stage ii ) . unlike in case 1 , incision line and anatomical landmarks for endoscpoic neck dissection were outlined on patient 's neck.(fig . 1 ) a retroauricualr incision was used to approach the sternocleidomastoid muscle ( scm ) and a skin flap was created . the scm muscle was exposed , then we continued subplastysmal dissection inferiorly and anteriorly until we reach the omohyoid muscle , hyoid bone and the midline of the neck . during skin flap elevation , a self - retaining retractor ( sejong medical corporation , paju ; sangdosa , seoul , korea ) was used for good visualization of the surgical field . a nerve stimulator was used to identify the marginal mandibular branch of the facial nerve . some portions of level ib , iia , and iii were also dissected under direct visualization . then , a 30-degree endoscope ( 10 mm in diameter , 30 cm in length ; stryker , san jose , ca , usa ) was applied in the level i area followed by fixation with an endoscope holder ( karl storz , tuttlingen , germany).(figs . 2 , 3 ) dissection of the anterior belly area ( level ia ) was performed ; then , level ib , which contains the submandibular gland , was dissected . harmonic curved shears ( harmonic ace 36p ; johnson & johnson medical , cincinnati , oh , usa ) were used to cauterize minor vessels and dissect tissues . the distal facial artery and vein were ligated with premium surgiclips ( covidien , dublin , ireland ) ; the submandibular ganglion , wharton 's duct , proximal facial artery and vein were cut after ligation with surgiclips . we demarcated the level of omohyoid muscle , which is inferior to the border of level iii , and dissected lymphoadipose tissue superiorly from inferior margin using endoscope . finally , dissection of the carotid artery and internal jugular vein was performed with posterior retraction of the scm . micro - vascular surgery was performed in case 2 as usual manuals which have been done in conventional neck dissection.(fig . 4 ) donor vessels such as the proximal portion of facial artery , superior thyroid artery , and related veins were observed well under microscope . . however , an assistant had to retract the skin flap with an army - navy retractor for visualization of the operative field . gagner4 introduced endoscopic surgery as an alternative to conventional open neck surgery for parathyroidectomy in 1996 . since then , various trials for endoscopic surgery on the neck , including thyroidectomy5 , submandibular gland excision6 , sentinel node biopsy7 , and nd3 , have been performed . this technique was developed gradually and is currently used in the treatment of many patients . although postoperative period is not enough to discuss about results of postoperative scar , it can not be seen easily in the frontal view because the incision line is hidden along the posterior neck.(figs . 5 - 7 ) second , the procedure is minimally invasive and patients typically recover faster . the incision line is also shorter than that of the conventional method . although more retraction of the skin flap is needed and causes stretching of the flap , this did not lead to any postoperative complications in the present cases . we found that accurate nd could be obtained by the endoscopic approach . in the conventional method , it is difficult to dissect level iib precisely , but the endoscopic approach provides the best field of view on level ii and favorable fields of view on levels ib and iii . however , this technique may not be appropriate for unskilled operators who have less experience with endoscopy or are unfamiliar with surgical anatomy . endoscopy provides limited direct visualization compared to the conventional method , so it can be difficult to recognize the exact area where is being operated and control unexpected hemorrhages first , the overlying skin tends to be thin and punctured easily , since there is no platysma muscle on level ia . second , it is difficult to dissect the lymphoadipose tissues on level ia precisely compared with the conventional method because of the limited surgical field . this technique may also not be appropriate for lesions on the floor of the mouth , near the midline , or along the anterior mandible where lymphatic drainage occurs to level ia . first , they proposed that endoscopic surgery causes inconveniences to the operator and assistant due to limited space . second , the robotic system has wrist articulated movement , which enables an unlimited operation field in a narrow working space compared to the endoscope . third , the robotic system provides more assistance with its arm . however , its high cost is a distinct disadvantage of robotic surgery3,8 . according to our experience , most patients diagnosed with oral cavity cancer are elderly , and are more concerned about cost than neck scarring . prominent postoperative scarring can be a major problem for patients . endoscopic nd is a little bit more expensive than the conventional approach , but cheaper than robotic surgery , and causes fewer scars compared to the conventional approach . thus , we consider endoscopic nd as an alternative to robotic surgery in terms of cost and postoperative scarring . oral and maxillofacial surgeons should make an effort to gain experience in endoscopic surgery and robotic surgery . unfortunately , there is no long - term follow - up information on patient outcomes involving these surgeries . thus , it is impossible to compare oncologic outcomes between endoscopic nd and conventional nd .