Critical Evaluation of Implant Treatment Planning with a Radiological Undetectable Inferior Alveolar Nerve

Case Report

J Dent & Oral Disord. 2016; 2(2): 1010.

Critical Evaluation of Implant Treatment Planning with a Radiological Undetectable Inferior Alveolar Nerve

Orechovsky B*, Bryk C and Von See C

Center for CAD/CAM and Digital Technologies in Dentistry, Danube Private University, Austria

*Corresponding author: Bernhard Orechovsky, Center for CAD/CAM and Digital Technologies in Dentistry, Danube Private University, Krems, Austria

Received: February 29, 2016; Accepted: March 31, 2016; Published: April 02, 2016


Backwards planning in dental implantology helps to achieve optimal prosthetic results. For implant surgery in the mandible highest patient-safety is necessary. Therefore, in the radiological image of the mandible the nerve position must be clearly defined. Changes of the nerve position caused by cysts or after trauma can lead to different treatment planning or might result in unexpected complications especially during implant surgery. This article critically discusses the decision tree and risk assessment and shows a clinical case where nerve detection was not possible.

Keywords: Alveolar nerve; Cone beam CT; Decision tree; Risk assessment; Short implants; Nerve disposition; Piezo surgery; Minimal invasive implantology


IAN: Inferior Alveolar Nerve; CT: Computed Tomography; CBCT: Cone Beam CT; -: no; +: yes


The complex and advanced developments in dental implantology and guided surgery maintain high success rates. According to numerous studies, if implants are inserted and restored by today’s standards, the success rate is about 95% over ten years [1]. The incidents of periimplantitis and implant failures under these conditions are less than 5% [2]. If clinical relevant risk factors or misdiagnosis occurs, this results in significant lower success rates [3].

None the less complications such as implant loss, technical complications or nerve damage can occur [4]. Especially in the mandibular molar region individual anatomical structures of every patient may vary [5]. This might become a major challenge in treatment planning. Irritation of the inferior alveolar nerve after surgical treatment such as wisdom tooth osteotomies is often described [6]. These irritation phenomena are observed in non-surgical endodontic in rare cases. The following reasons for nerve irritations are given: The most common cause is, according to a summary of an article by Knowles, the overfilled root filling material in the nerve canal within the framework of an endodontic treatment [7]. As a consequence, a paresthesia up to a complete loss of sensitivity is reported, or pain was only mentioned in very few cases [8,9]. Caused by an infection a sensibility disturbance can occur due to a displacement of infectious materials or chemicals [10]. This can be treated surgically or with appropriate medication. A similar phenomenon is known as the Vincent-Symptom. After a block anesthesia on the Inferior Alveolar Nerve (IAN), due to toxic or physical damage a mostly reversible nerve irritation can occur [11, 12]. Seldom reported, as in the article by Krogstad et al. (1997), is a paresthesia after orthodontic treatments displacement of teeth causing close contact with the IAN [13].

Besides the postoperative wound infection, damage to the inferior alveolar nerve plays a significant role. Complications and healing intervals are dependent on the age of the patient and rise significantly in patients over 25 years of age [14].

An IAN channel has a large variance in its position. It is located from 4.9 mm to 17.4 mm from the buccal side and runs precise on the high-level cortical surface of the mandible. The buccal tongue IAN canal position is influenced by age and race. On the average, older and white patients have a shorter gap between the buccal side of the canal and the tongue-side of the mandible border. To reduce the risk of an IAN injury, these variables must be taken into consideration when planning a mandible osteotomies or using monocortical plates [15].

Nerve displacement correlating to mandibular cysts

Solitary bone cysts mostly arise in the second decade of people’s lives, and men and women are equally affected [16]. Solitary cysts usually occur exclusively in the lower jaw, and are mainly located in the corpus and the symphysis.

In general, solitary bone cysts are lesions displaying no clinical symptoms. They are usually discovered by accident during routine radiological examinations. The clinical findings are generally vestibular situated swellings, rarely causing pain or paraesthesia of the lips [17].

Radiological findings in cysts are a sharp, restricted, roundish or osteolytic with a partial sclerotic edge. Often there is an interdental, to be precise, an intraradicular, expanse which is described as scalloped in shape. In accordance with the radiological findings, which barely ever show signs of resorption of the apex or nerve resorption patients rarely complain of pain or paresthesia. In these cases, the nerve is displaced by the cyst without resorption or destruction. Other factors such as orthognathic surgery or a trauma can result in a nerve disposition [18]. Even when the common therapy like a careful removal of the fibrous heath of the cavity, and to induced bleeding for a bony consolidation is performed, the nerve will not reposition.

As nerve disposition, due to cysts might occur dental implant treatment planning can be challenging. Due to this fact, the changing courses of nerve tracts in the oral cavity can lead to unexpected complications especially during implant surgery.

As patients are statistically getting older and having lower bone remodeling rates as well as lower general health status, new techniques for dental implant treatments are necessary. This nowadays leads to increasingly shorter implants being inserted to avoid augmentation procedures. Short implants are discussed critically in literature. Overall the failure rate of long implants compared to short implants is the same when the loading axis was taken into account [19]. The use of short implants in cases where nerve detection is radiologically not feasible has not been described yet. Therefore, the decision-making process of cases with undetectable alveolar nerve was described and a corresponding case report is presented.

Case Presentation

A 49 years old patient presented at the dental clinic Danube Private University (DPU) in Austria, with a referral from her dentist, and requested implants at the missing teeth 36 and 46.

As an anatomical abnormality a post-traumatic displacement of the inferior alveolar nerve after an accident in 1987 was presumable. Further medical history showed a diagnosed fibromyalgia and minimal regular consumption of alcoholic beverages. The patient is a smoker and suffers occasional bouts of claustrophobia. She regularly takes the prescribed medication Pregamid (GL pharma, Austria) in order to cope with and control the sudden claustrophobic attacks. The patient showed no signs of paresthesia in the left and right lower jaw preoperatively.

Clinically the first molars (36 and 46) were missing in the lower jaw. In a standard Orthopantomography (OPG) the alveolar nerve in the left jaw was undetectable (Figure 1).