Preoperative assessment of labial bone perforation for virtual immediate implant surgery in the maxillary esthetic zone: A computer simulation study.

BACKGROUND: In this computer simulation study, the authors investigated the frequency distribution of labial bone perforation (LBP) between various sagittal root position (SRP) classes with respect to the anterior maxillary osseous housing and evaluated the associated factors correlated with a higher risk of LBP when performing a virtual immediate implant surgery in the esthetic zone. METHODS: The authors analyzed cone-beam computed tomography (CBCT) images from 285 qualified study participants (1,449 teeth) to determine the probability of LBP when associated with selected variables, such as tooth type, SRP class, and morphologic parameters. The authors examined associated factors and analyzed the adjusted odds ratios by means of multiple logistic regression analysis. RESULTS: The overall probability of LBP was 81.7%, which presented statistically significant differences between each specific tooth type and SRP class (all P<.001). After adjusting for other factors, the authors found that the maxillary central incisor was 2.37 times more likely to have LBP than the canine. SRP class I was 4.9 times more likely to be associated with LBP when compared with SRP class IV. CONCLUSIONS: When a clinician performs an immediate implant in the anterior esthetic zone, he or she should be aware that the specific tooth type, SRP class, and morphologic features of fossa concavities are associated with a risk of experiencing LBP. PRACTICAL IMPLICATIONS: Presurgical cross-sectional images can be analyzed to identify anatomic features relative to LBP in the maxillary esthetic region, and this can avoid unpleasant complications, specifically when performing immediate implant procedures.

Risk of lingual plate perforation for virtual immediate implant placement in the posterior mandible: A computer simulation study.

BACKGROUND: This study sought to determine which factors are correlated to a higher risk of lingual plate perforation (LPP) when placing a virtual implant in the area of the anticipated extraction site of the posterior mandible. METHODS: Computed tomographic images of 300 patients (1,279 teeth) were analyzed in regard to the shape of the mandible (convergent, parallel, or undercut type), dimensional parameters of lingual concavity (angle, height, depth) and its relation to the inferior alveolar canal (zones A, B, C), distance from root apex to inferior alveolar canal, and probability of LPP. The odds ratio of variables was determined by multiple logistic regression modeling. RESULTS: The overall probability of LPPs on virtual implant placement was 3.1%. This perforation was most commonly observed at the second molar and with a U-type ridge. After adjusting cofounders, a concave point located in zone A is 17.34 times more likely to have a LPP than one in zone C. The probability of LPPs was reduced by 34% for every 1-millimeter increase in distance from root apex to inferior alveolar canal on virtual implant placement of posterior mandible region. CONCLUSIONS: Three-dimensional cone-beam computed tomographic imaging is essential for planning immediate implant placement in the anticipated extraction sites of the posterior mandible region as proved by anatomic findings that can only be understood from preoperative imaging analysis. PRACTICAL IMPLICATIONS: Presurgical cross-sectional images can be analyzed to identify anatomic features relative to the lingual concavities in the posterior mandible region, which can help to avoid unpleasant complications, specifically when performing immediate implant procedures.

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 1mm 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.

Nasopharyngeal carcinoma metastatic to the mandible.

Nasopharyngeal carcinoma (NPC) is one of the most common malignancies in the head and neck region, especially among those of Chinese origin. NPC has multifactorial aetiologies including genetic susceptibility, consumption of food with high salt content, and the Epstein-Barr virus. The primary tumour usually arises from the lateral walls of the nasopharynx and is characterized by a rich sub-mucosal lymphatic structure, often leading to cervical lymph node metastasis. Distant metastasis has been recognized to be a major cause of treatment failure in patients with nasopharyngeal carcinoma. Bone, liver and lung are the most frequent sites of NPC metastases.