Anatomical variations of the ethmoid sinuses and their association with health or pathology of the ethmoid and maxillary sinuses in a Southern Chinese population: An analysis using cone-beam computed tomography.

Purpose: The aim of this study was to evaluate the prevalence of clinically relevant anatomical variations of the ethmoid sinuses and their potential association with ethmoid and maxillary sinus pathologies on cone-beam computed tomography (CBCT) scans. Additionally, potential associations with different sides and demographic factors, including age and sex, were evaluated. Materials and Methods: In total, 273 CBCT scans with complete ethmoid and maxillary sinuses were analyzed to determine the prevalence of Agger nasi cell, supraorbital ethmoid cell, Haller cell, Onodi cell, and ethmomaxillary sinus. In addition, the health or pathology of the ethmoid and maxillary sinuses was also recorded to assess correlations with the aforementioned variations. Results: The prevalence of Agger nasi cell was found to be the highest (95.6%) in this study, followed by Onodi cell (60.4%), Haller cell (29.3%), and supraorbital ethmoid cell (19.4%). Ethmomaxillary sinus was the least common finding (16.5%). Males and persons above 61 years of age had a significantly higher frequency of supraorbital ethmoid cell and Onodi cell, respectively. However, no significant relationships were noted between anatomical variations of the ethmoid sinus and pathologies of the ethmoid or maxillary sinus. Conclusion: There was a high prevalence of ethmoid sinus variations in this Southern Chinese population. The prevalence of Agger nasi cell and Onodi cell was higher than that of other anatomical variations of the ethmoid sinuses. Anatomical variations of the ethmoid sinuses were not associated with ethmoid or maxillary sinus pathologies in this patient cohort.

[Mucous retention cyst of the alveolar bone radiologically mimicking a radicular cyst: A case presentation.] / Aussergewöhnliche Schleimretentionszyste im Kieferknochen imponiert radiologisch als radikuläre Zyste. Ein Fallbericht.

One of the most frequent pathologies of jaw bone is a bacteria-induced inflammation at the apices of teeth with subsequent bone resorption that typically presents as a radiolucency in radiographs. Usually, corresponding clinical and radiographic findings correlate and allow for an accurate diagnosis. However, occasionally an unexpected and completely different diagnosis presents as documented in this case report. In a 55-year-old female patient, a radicular cyst was suspected in her right maxillary bone. The treatment plan included a cystectomy as well as apical surgery of the adjacent and root-canal filled teeth 15 and 16. However, the intraoperative finding absolutely did not fit a radicular cyst but rather a mucous retention cyst, as could be confirmed subsequently by histopathology. The diagnosis of a mucous retention cyst within the jaw bone is extraordinary and as such has never been described before in the literature.

Neurosensory Disturbances After Apical Surgery of Mandibular Premolars and Molars: A Retrospective Analysis and Case-Control Study.

OBJECTIVE: Apical surgery is an intervention to treat teeth with persistent or recurrent endodontic infection. The proximity of the mental foramen and mandibular canal may pose a risk of altered sensation when performing surgical interventions in the posterior mandible. The objective of this study was to determine the rate of neurosensory disturbances after apical surgery of mandibular premolars and molars. The secondary objective was to evaluate whether the occurrence of altered sensation correlated with the distances from the apex or the periapical lesion to the relevant anatomical structures. METHODS: The charts of patients treated from September 1999 to December 2015 were retrospectively evaluated if an apical surgery had been performed in mandibular premolars or molars, and a minimum period of 1-year follow-up was documented. Patients with trauma or other surgical interventions in the same hemimandible were excluded. Cases with postsurgical altered sensation were defined as the test group. From the pool of unaffected cases, patients were selected to serve as controls. Two- or three-dimensional radiographs of test and control cases were assessed with regard to the shortest distances from the root apices/lesions to the mental foramen or mandibular canal. RESULTS: The study population included 243 patients with 249 apical surgeries, of which 12.9% led to postoperative neurosensory disturbances. Sensation returned to normal within 22 days on average. The most frequent findings were hyperesthesia or paresthesia. With regard to the treated type of tooth, second premolars resulted more frequently (22.6%) in altered sensation than the other teeth (11.2 to 13.0%; p=0.310). There were no significant differences when comparing test and control cases regarding the measured distances in radiographs from the apex/lesion to the relevant anatomical structures. CONCLUSION: Altered sensation may typically occur following apical surgery in posterior mandibular teeth. However, in all cases of the present study, skin sensitivity in the lip/chin region returned to normal. The clinician must be particularly careful when performing apical surgery of second premolars due to the proximity of the mental foramen.

[Misinterpretation of a periapical radiograph: the canalis sinuosus mimicking a root resorption]. / Fehlinterpretation im Röntgenbild. Der Canalis sinuosus als radiologisch-anatomische Vortäuschung einer Wurzelresorption.

There is widespread knowledge that the mental foramen or incisive foramen can be projected onto tooth roots in conventional radiographs, thus simulating apical lesions. In contrast, the anatomical structure of the canalis sinuosus and its branching canals in the anterior maxilla are less known. Sometimes these bone canals mimic a dentino- or osteolysis on conventional radiographs. If these bone canals project onto the roots of the anterior maxillary teeth, there is a risk of misinterpretation as root resorption or apical periodontitis. This case report presents an incidental radiological finding. Due to a radiolucency within the root of tooth 11, root resorption was suspected. Using cone beam-computed tomography, the origin of this radiolucency was clearly identified as an anatomical structure, and the suspected diagnosis was ruled out. This case highlights the importance of the knowledge of anatomical structures to avoid misinterpretations and unnecessary treatments.

Outcome of Periapical Surgery in Molars: A Retrospective Analysis of 424 Teeth.

INTRODUCTION: The objective of this retrospective study was to assess the outcome of periapical surgery in a large number of molars in order to identify possible variables that might affect the outcome. METHODS: The healing outcome of patients undergoing periapical surgery of molars from October 1999 to October 2019 was retrospectively evaluated. Outcome was dichotomized into "healed" and "nonhealed" using well-established clinical and radiographic healing criteria. The potential influence of patient-, tooth-, and treatment-related parameters on the healing outcome was analyzed. RESULTS: A total of 424 molars in the same number of patients (45.5% male and 54.5% female) were evaluated. Three hundred seventy-two molars were classified as healed (87.7%). Three significant outcome predictors were identified: 1-year follow-up versus >1-5 years, >5-10 years, and >10 years (95.3% vs 82.2%, 76.3%, and 76.5% healed, respectively; P < .0001); root end filling material with bioceramic root repair material versus mineral trioxide aggregate (96.9% vs. 86.3% healed, respectively; P = .001); and preoperative evaluation based on cone-beam computed tomographic imaging versus 2-dimensional radiography (90.2% vs 81.4% healed, respectively; P = .02). Sex, age, tooth location, type of restoration, attachment level, presence of a post, quality of the root canal filling, technique of root end preparation, administration of antibiotics, and type of surgery had no significant impact on the healing outcome. CONCLUSIONS: The healed rate for the concave (Retroplast) and cavity (mineral trioxide aggregate, SuperEBA [Staident International, Staines, UK], and bioceramic root repair material) root end preparation technique over all follow-up periods was 84% and 88.5%, respectively. The follow-up period, root end filling material, and preoperative evaluation based on cone-beam computed tomographic imaging had a significant influence on the healing outcome.

Morphometric characteristics of the sphenoid sinus and potential influencing factors: a retrospective assessment using cone beam computed tomography (CBCT).

The present study aimed to evaluate the morphological characteristics of the sphenoid sinus (SS), and the impact of potential influencing factors on the morphometric features using CBCT imaging. CBCT scans of 148 patients, aged between 15 and 85 (32.88 ± 15.33) years were retrospectively evaluated. DICOM files from the CBCT scans were imported into semi-automatic software and the SS of each patient was assessed for the morphological characteristics including configuration, symmetry, extension, shape, septation, volume, and maximum diameter. Furthermore, potential influencing factors such as age, gender, side, and sinus condition were analysed. A significant association was observed between sinus extension and age. Septation was also found to be significantly associated with age, gender and sinus condition. Besides, sinus volume was significantly associated with gender and sinus condition. No significant influence of shape and side on the morphometric features was noticed. The average volume and diameter of the SS were 6576.92 ± 3748.12 mm3 and 30.48 ± 9.28 mm, respectively. In conclusion, the present findings indicate that age, gender and sinus condition have a significant impact on the morphometric characteristics of the SS. Mature sinuses exhibit a post-sellar extension pattern until middle age. In addition, males, and sinuses with healthy sinus condition have larger volumes compared to females and pathological sinuses.

The anatomical variability of the sphenoid sinus in CBCT - a retrospective study.

The aim of this retrospective study was to assess and illustrate the anatomical variability of the sphenoid sinus (SPS) on cone-beam computed tomography (CBCT) scans. A total of 50 SPS were assessed. CBCT images were oriented in the sagittal plane to evaluate the type of pneumatization (conchal, presellar, sellar and postsellar). Size measurements (width, length and height) of the SPS as well as the septation pattern and the presence or absence of pathologies were examined in all three planes. The postsellar type (28 cases, 56%) was the most common pattern of pneumatization. Conchal, presellar, or sellar pneumatization were significantly less frequent. There was only one case (2%) with a conchal and two cases (4%) with a presellar type. Multiple septa were found in 75% of patients with postsellar pneumatization, but only in 45.5% of patients featuring conchal, presellar or sellar type. In the postsellar category, all measured dimensions were significantly higher compared to the other types of pneumatization. Pathologies in the SPS were found in 7 patients (14%). It was concluded that the anatomical structure of the SPS is highly variable. Knowledge about its radiological appearance in CBCT will help in identification of pathologies and surrounding anatomical structures.

Long-term effectiveness of 6 mm micro-rough implants in various indications: A 4.6- to 18.2-year retrospective study.

OBJECTIVES: To evaluate the long-term effectiveness of 6 mm implants in various indications with a micro-rough surface after 4.6-18.2 years in function and to assess key factors associated with implant survival, success, and biologic/technical complications. MATERIALS AND METHODS: Fifty-five patients with seventy-four 6 mm implants placed from 2000 to 2013 attended the re-examination assessing well-established clinical and radiographic parameters, biologic and prosthetic complications, and patient-reported outcome measures. RESULTS: Five implants were lost after a mean follow-up period of 9.1 years resulting in a survival rate of 93.2%. All losses occurred in free-end situations in the mandible. Smoking habit significantly reduced implant survival (hazard ratio 36.25). Two implants exhibited a history of peri-implantitis, and one implant showed progressive marginal bone loss (MBL) resulting in a success rate of 89.2%. The mean MBL amounted to 0.029 mm. Increased MBL was found for implants placed in the maxilla (0.057 mm) and for implants with a diameter of 4.1 mm (0.043 mm). Soft tissue thickness (1.39 mm) and width of keratinized mucosa (1.91 mm) had no effect on MBL. Patient-reported outcome measures showed high satisfaction (mean VAS scores 88%) and high quality of life (mean OHIP-G14 score 2.2). CONCLUSION: The present study demonstrated survival and success rates of 93.2% and 89.2% for 6 mm implants used in various indications. A factor leading to higher implant failure was smoking, whereas modulating factors increasing annual MBL included implants placed in the maxilla and implants with a diameter of 4.1 mm compared to 4.8 mm.

Retrospective Analysis of Dento-alveolar Injuries at a Swiss University Clinic (2011-2015).

The aim of this study was to evaluate all dento-alveolar injuries occurring within a period of 5 years that were examined at the Department of Oral Surgery and Stomatology at the University of Bern. The case histories of 852 patients (522 males and 330 females) were assessed retrospectively. The mean age was 17 years and 9 months. The youngest patient was 10 months old, the oldest was 91 years old. Most accidents were recorded in the months of March and July. Friday was observed as the weekday when accidents were at their peak. 54% of trauma patients were first examined on the day of the accident. The most frequent causes of accident were falls, cycling or sports accidents. Injury types included concussion (72.4%), subluxation (14%) and luxation (7.7%). Crown fractures without pulp exposure were recorded in 522 teeth (10.7%). Rare types of trauma were crown fractures with pulp exposure (3.7%), and avulsion injuries (3.2%). The most frequently affected teeth were central incisors (40%), followed by lateral incisors (35.6%) and canines (19.5%). 71.5% of the patients with dento-alveolar trauma also had soft-tissue injuries (from abrasions to lacerations), mostly lip (51.6%), gingival (19%), and chin injuries (10.9%). The multivariate analysis showed that age had a significant impact on concussions, subluxations, intrusions, crown fractures, root fractures and non-oral injuries. For concussions and subluxations, the probability of an injury was the highest for the mixed dentition group. For intrusions, the probability of an injury decreased with age, but it was vice versa for crown fractures, root fractures and non-oral injuries. It was found that bicycle injuries had the highest injury probability for avulsions, luxations, subluxations, soft tissue - and non-oral injuries.

Occurrence of Vertical Root Fractures after Apical Surgery: A Retrospective Analysis.

INTRODUCTION: Vertical root fractures (VRFs) are among the most frequent causes of tooth loss, mainly of endodontically treated teeth. However, very few data is available about the occurrence of VRFs following apical surgery. METHODS: Patient charts from 864 patients with 1058 teeth treated with apical surgery (September 1999 to December 2018) were retrospectively evaluated, if a VRF had occurred after surgery. The following, possibly influencing factors were analyzed: sex and age, type of treated tooth, primary versus resurgery, technique of root-end preparation, and timepoint of VRF diagnosis. Endpoints were either tooth extraction or the last follow-up. RESULTS: The study cohort (55% women, 45% men) had a mean age of 52.00 ± 13.97 years (range 9-93 years). The overall rate of VRFs after apical surgery was 4% (42 of 1058 teeth). Among these 42 teeth, 33.3% were mandibular first molars and 26.2% were maxillary second premolars. The most frequently affected root was the mesial root of mandibular first molars (28.6%). With regard to the study parameters, significant differences of VRF rates were observed only for the type of tooth treated. CONCLUSIONS: A low VRF rate of 4% was observed in this study. VRFs commonly occurred in maxillary premolars and mandibular molars, with the mesial root of mandibular first molars affected most frequently. This is in line with previous reports about VRFs in endodontically treated teeth without additional apical surgery.

A retrospective analysis of autotransplanted teeth including an evaluation of a novel surgical technique.

OBJECTIVES: To assess survival rates and frequency of complications for immature and mature autotransplanted teeth after at least 1 year in function. MATERIALS AND METHODS: All consecutive patients who had undergone tooth autotransplantation between 2000 and 2018 were invited to a clinical and radiographic follow-up examination. First, survival rates were calculated on the basis of a phone inquiry. A clinical follow-up examination allowed for the calculation of the success rate, i.e., absence of any potentially adverse clinical and radiographic findings of the autotransplanted teeth. Moreover, the effect of demographic, dental, and surgical variables on survival/success was analyzed statistically. RESULTS: Thirty-eight teeth in 35 patients were transplanted during the study period. Three teeth in 3 patients were excluded due to missing records. All other patients were successfully contacted and interviewed by phone. Out of these 35 transplants, 32 were still in function, and 3 had been extracted, yielding a 91.4% survival probability after a median follow-up of 3.4 years. Of the 32 teeth qualifying for the success analysis, 20 (62.5%) showed absence of potentially adverse findings, while 3 (9.4%) required root canal treatment (RCT). Out of the 9 mature, root-end resected transplants, 4 exhibited ongoing pulp canal obliteration, all with a single root canal. Postoperative and potentially adverse findings or failures were found more frequently in the group of mature transplants (55.6%) than immature transplants (30.4%) and for molars (72.7%) than premolars (17.6%) or canines (25%). None of the potential predictors had a statistically significant effect on survival or success. CONCLUSION: Autotransplanted teeth yielded a satisfying midterm survival rate regardless of their stage of development. An additional, extraoral root-end resection of mature transplants may lead to rates of revascularization and postoperative pulp canal obliteration higher than the data reported on unmodified mature transplants. CLINICAL RELEVANCE: Extraoral root-end resection of mature teeth shows promising outcomes for transplants especially with a single root canal and uncomplicated root morphology.

The bifid mandibular canal in three-dimensional radiography: morphologic and quantitative characteristics.

The mandibular canal is a prominent anatomical structure and it is of great clinical importance since it contains the inferior alveolar nerve. The clinician is advised to proceed cautiously in the vicinity of the mandibular canal to avoid any damage to its neurovascular content. Based on observations in dry mandibles, in panoramic radiographs, and recently in three-dimensional radiography, various anatomical variations of the mandibular canals have been described. One such variant is the so-called bifid mandibular canal (BMC). Embryologically, multiple canals develop and subsequently fuse to form a single mandibular canal; however, occasionally fusion fails or is incomplete resulting in one or multiple BMCs. Clinically relevant issues with regard to the BMCs include hemorrhagic or neurological disorders following damage to these aberrant canals. This literature review presents morphological and quantitative data about BMCs from studies using three-dimensional radiography, i.e. CT and/or CBCT. The reported frequencies of BMCs per patient ranged from 9.8 - 66.5% and per mandibular side from 7.7 - 46.5%. Gender, age or side predilection is currently inconclusive with regard to the occurrence of BMCs. Various types of BMCs have been described in the literature, such as retromolar, dental, forward, or buccolingual canals. BMCs may originate from the mandibular canal along its entire course, but bifurcation appears to be more frequent in the posterior compared to the anterior canal portions. Mean BMC length was reported to range from 10.2 - 16.9 mm, and mean BMC diameter from 0.9 - 2.3 mm. In conclusion, the presence of a BMC must be taken into consideration for treatment planning and anesthetic, endodontic, or surgical interventions in the mandible.

Outcome of first-time surgical closures of oroantral communications due to tooth extractions. A retrospective analysis of 162 cases.

The objective of this study was to analyze the outcome of first-time surgical closures of oroantral communications (OAC) after tooth extractions. Using a billing software, all patients treated in a surgery department were filtered for interventions of the maxillary sinus indicative of OAC therapy. Out of 221 initially eligible cases, the charts of 162 cases fulfilling the inclusion criteria were retrospectively evaluated for the outcome in terms of symptom-free OAC closure as well as possibly influencing patient and treatment factors. The analyzed cohort included 98 males (60.5%) and 64 females (39.5%) with a mean age of 48.6 years (range 17 to 86 years). The maxillary 1st molar (38.3%) was the most common site requiring OAC closure. In 60.5% of the cases, surgical OAC closure was performed immediately after tooth extraction. The Rehrmann flap (72.2%) was the most frequently used technique for surgical OAC closure. 94.4% of surgical OAC closures were successful. Gender and age did not influence the outcome. In contrast, the site of OAC and the time interval from tooth extraction to OAC closure affected the results. Furthermore, the Rehrmann flap, alone or in combination with biomaterials, was superior to the mere suturing (with or without biomaterials) of the OAC site. In conclusion, the Rehrmann flap alone or in combination with biomaterials provided high success rates for first-time surgical OAC closure. With regard to the study parameters, an OAC in the 3rd molar area and an extended interval from tooth extraction to OAC closure negatively influenced the resolution of OAC. However, results must be interpreted cautiously considering the retrospective study design and the limited number of cases.

The use of the endoscope in endodontic surgery: A systematic review.

BACKGROUND: A systematic review of clinical studies with at least one year of follow-up was done to assess the success rate of endodontic surgery including endoscopy for magnification and illumination. MATERIAL AND METHODS: Five electronic databases were searched, including MEDLINE (via PubMed), Embase, Web of Science, Scopus and the Cochrane Library of the Cochrane Collabora-tion (CENTRAL). There were no language restrictions, and the search covered the period up to October 2019. The risk of bias was evaluated with the Cochrane Collaboration tool for randomized clinical trials and the ROBINS-I tool for non-randomized studies of inter-ventions. RESULTS: From the 278 initially identified titles, finally 2 randomized controlled trials and 3 non-randomized studies met the inclusion criteria. All the included studies analyzed the success rate of endodontic surgery performed with the help of endoscope for magnifica-tion and illumination. The risk of bias was high for allocation sequence concealment and blinding of participants and personnel in the randomized controlled trials. The nonran-domized studies showed limitations in terms of confounding bias and blinding of outcome assessment. Endodontic surgery with the help of an endoscope is associated with high success rates (88.9-94.9%). CONCLUSIONS: The endoscope was associated with high success rates of endodontic sur-gery in the included studies. Future studies on this topic are warranted, due to the meth-odological issues and the scarce number of randomized clinical trials. Key words:Endodontic surgery, magnification, endoscope, success.

Extraoral anatomy in CBCT ­ a literature review. Part 4: Pharyngocervical region

This review about extraoral anatomy depicted in cone beam computed tomography describes the pharyngocervical region. Large (≥ 8 × 8 cm) field of views of the maxilla and/or mandible will inevita-bly depict the pharyngocervical region that com-prises the posterior upper airway, the pharyngeal part of the digestive tract, as well as the cervical segment of the spine. The latter consists of seven cervical vertebrae (C1-C7) with corresponding distinctive features, i.e., the atlas (C1) and the axis (C2). In addition, cervical vertebrae serve as ref-erences for the vertical position of anatomical structures. For instance, C4 is a typical landmark since it generally denotes the level of the chin, of the body of the hyoid bone, of the base of the epiglottis, and of the bifurcation of the common carotid artery, respectively. The pharynx, which is functionally involved in respiration, deglutition, and vocalization, extends from the lower aspect of the skull base to the esophagus. Anatomically, the pharynx is divided into three segments, i.e. the nasopharynx, the oropharynx, and the laryn-gopharynx. All communicate anteriorly with cor-responding cavities, i.e. the nasal cavities, the oral cavity, and the larynx. Although not directly located within the pharyngocervical region, the hyoid bone and the styloid process are also dis-cussed in this review, since both structures are commonly visible on CBCT images of this region.

Perforation of the maxillary sinus floor during apical surgery of maxillary molars: A retrospective analysis using cone beam computed tomography.

This retrospective analysis assessed a possible correlation of perforation of the maxillary sinus floor during apical surgery of maxillary molars and the distances from the treated apices/periapical radiolucencies to the sinus floor. The material included 168 apical surgeries of maxillary first or second molars performed from 1999 to 2016. In 22 (out of 33) perforation cases, a preoperative cone beam computed tomography (CBCT) was available. These cases were defined as the test group. From the pool of operated cases without sinus floor perforation, matching cases - that is, same treated tooth, similar age and same gender - were selected as a control group (N = 26). Mean linear distances from root apices or radiolucencies to sinus floor were significantly shorter in the test group compared to the control group. In conclusion, perforation cases were significantly closer to the sinus floor than cases without perforation.

Bioceramic root repair material (BCRRM) for root-end obturation in apical surgery. An analysis of 174 teeth after 1 year.

The objective of this paper was the analysis of the 1-year outcome of teeth treated with apical surgery and a recently introduced bioceramic root repair material (BCRRM) for root-end filling. Patients were consecutively enrolled from 2015 to 2017. Apical surgery included the modern technique, i.e. the use of a surgical microscope, ultrasonic preparation of a root-end cavity, and retrofilling with BCRRM. The cohort comprised 150 patients with 174 treated teeth. Patients were recalled one year after surgery for a clinical and radiographic re-examination. Three experienced observers evaluated the periapical radiographs with regard to periapical healing utilizing the healing criteria established by Rud et al. (1972) and Molven et al. (1987). Based on the clinical findings and the radiographic assessment, healing was judged as successful, uncertain, or failed. Study parameters included gender, age, type of treated tooth, and type of BCRRM (regular vs. fast set putty). At the 1-year follow-up, 170 teeth could be reexamined (drop-out rate 2.3%). Healing outcome was categorized as successful in 94.1%, uncertain in 4.1%, and failed in 1.8%. No significant differences were observed when comparing the success rates among the different subcategories of study parameters. The lowest success rate was noted in mandibular premolars (86.7%) but without reaching statistical significance. In conclusion, BCRRM appears to be a biocompatible root-end filling material showing excellent 1-year results. The success rate was similar to recently reported success rates for BCRRM in apical surgery.

Extraoral anatomy in CBCT ­ a literature review. Part 3: Retromaxillary region

In this review about extraoral anatomy as depicted by cone beam computed tomography, the retromaxillary region is discussed. A medium-sized (6 x 6 cm) or large (≥ 8 x 8 cm) field of view of the maxilla will inevitably depict the retromaxillary region that can be considered a «transition¼ zone between the viscerocranium and the neurocranium. Major structures of the region include the sphenoid bone and the pterygopalatine fossae. The sphenoid bone is a single but complex bone located between the maxilla and the brain. It is composed of a central body, bilateral greater and lesser wings, and pterygoid processes. Important neurovascular structures pass through the sphenoid bone: the optic nerve and the ophthalmic artery via the optic canal, the maxillary nerve via the foramen rotundum, and the pterygoid nerve via the Vidian canal. The central body of the sphenoid bone also contains the highly variable sphenoid sinus that is the most posteriorly located paranasal sinus. The bilateral pterygopalatine fossae behind the maxillary sinuses contain several important neurovascular structures that supply the maxilla and the midface.

Extraoral anatomy in CBCT ­ a literature review. Part 2: Zygomatico-orbital region

This second article about extraoral anatomy as seen in cone beam computed tomography (CBCT) images presents a literature review of the zygomatico-orbital region. The latter bounds the maxillary sinus superiorly and laterally. Since pathologic changes of the maxillary sinus are a frequent indication for three-dimensional radiography, the contiguous orbital cavity and the zygomatic bone may become visible on CBCT scans. The zygomatic bone forms the cheek prominence and has large contact areas with the maxilla through the zygomaticomaxillary suture in the infraorbital region as well as with the sphenoid bone along the lateral orbital wall. Each of the three surfaces of the zygomatic bone displays foramina that transmit neurovascular structures. The orbital cavity is located immediately above the maxillary sinus from which it is separated only by a thin bony plate simultaneously serving as the orbital floor and the roof of the maxillary sinus. Several openings, such as the superior and inferior orbital fissures, the ethmoidal and cranio-orbital foramina, and the optic and infraorbital canals, connect the orbit to the anterior and middle cranial fossae as well as to the infratemporal and pterygopalatine fossae.