_Applied_  
_sciences_  
_Repiew_  
**Type I Collagen-Based Devices to Treat Nerve Injuries after**  
**Oral Surgery Procedures. A Systematic Review**  
**[PERSON] 1,2,*,\({}^{\dagger}\)\({}^{\ddagger}\), [PERSON] 3,4,*,\({}^{\dagger}\)\({}^{\circled}\), [PERSON] 5,*, [PERSON] 6,7\({}^{\circled}\), [PERSON] 6\({}^{\circled}\), [PERSON] 8\({}^{\circled}\), [PERSON] 9\({}^{\circled}\) and [PERSON] 8\({}^{\circled}\)**  
(LN) [6]. Recently, a large retrospective university-setting clinical study on 1559 patients, reported sensorial disturbance in 42 cases (2.69%) with only five cases of persistent sensory disturbance (0.32%), and four of these five lesions were in the lingual nerve (0.25%) [7]. Consequently, despite the overall low percentage of complications, oro-facial disturbances cause considerable patients' morbidity in terms of social disabilities and physical pain negatively affecting the whole quality of life.  
More specifically, as summarized by [PERSON] and coworkers in 2014 [8], the impaired sensation caused by lesions at the inferior alveolar nerve has been classified as:  
* Paresthesia--An abnormal sensation, whether spontaneous or evoked.
* Anesthesia--Complete absence of perception of stimuli including touch.
* Dysesthesia--An unpleasant abnormal sensation, whether spontaneous or evoked.
* Hyperalgesia--Increased pain from a stimulus that normally provokes pain.
* Allodynia--Pain due to a stimulus that does not normally provoke pain.
* Hypoesthesia--Decreased sensitivity to stimulation, excluding the special senses.
* Hypeesthesia--Increased sensitivity to stimulation, excluding the special senses.
* The injury to the lingual nerve may also affect taste perception on the same side.
* Ageusia--Loss of taste perception.
* Dysgeusia--Altered taste perception.  
At the present time, a multitude of different surgical interventions has been proposed to treat nerve injuries at the IAN and LN [9], even-though no consensus has been yet reached [6]. Historically, the use of nerve grafts of autologous origin has been adopted: indeed, in cases of complete nerve injury where a tight approximation of the two nerve edges is not possible, the use of an interpositional graft (i.e., sural, greater auricular or antebrachial nerves) has been propagated mainly with the aim to avoid nerve tension, but to allow physical reconnection of the two injured nerve sections [10]. Nevertheless, the use of autologous nerve grafts often resulted in undesirable post-operative sequalae at the donor site [11].  
To overcome these side effects, during the last three decades, the use of hollow devices by means of a technique called stabilization has been proposed [12]. This procedure in intended to enhance nerve repair in cases of defects, which do not allow an intimate contact between the two injured nerve sections by means of a graft material.  
Originally proposed with autogenous material by [PERSON] and coworkers [13] by means of the use of the saphenous vein to repair IAN and LN injuries, alloplastic hollow conduits of different materials such as polyglycolic acid (PGA) bioabsorbable [14], Gore-Tex [15] and PGA-collagen tubes [16] have been launched to the market. Moreover, the FDA has also authorized the commercialization of type I collagen medical device to treat nerve injuries at IAN and LN, considering that they allow an appropriate nutrient diffusion and retention of representative nerve growth factor [17]. Until now, however, no attempt has been done to summarize the level of evidence behind the clinical use of such devices oral-surgery procedures.  
Therefore, the purpose of the present systematic review was to evaluate the current evidence of on the use of type I collagen-based devices for mandibular or lingual nerve injuries regeneration after oral surgery procedures.