Increased safety in periodontal surgery: Doppler ultrasound for detection of relevant palatal blood vessels-A proof-of-concept and cross-sectional study.

AIM: To evaluate the suitability of a Doppler ultrasound probe in detecting the greater palatine artery or its greater branches non-invasively. MATERIALS AND METHODS: The palatal mucosa of 108 participants (median age 34 years, 51 female) was systematically divided into transversal sectors, each aligning with the positions of the upper molars (M), premolars (P) and canine teeth (C), aiming to facilitate precise and consistent localization of the detected palatal blood vessel across different patients. Blood flow of the palatal blood vessels, presumably, was located by scanning the palatal vault bilaterally using an 8-MHz ultrasound probe linked to a transducer. The distance to the corresponding tooth was measured using a millimetre-scale periodontal probe. RESULTS: Within the regions of M2 to P1, the ultrasound transducer gave a delimitable acoustic pulse signal in 80%-98% of all measurements. The measured median distances between the determined position of the artery and the corresponding teeth ranged from 13 to 15 mm, with smaller distances in the anterior region. In several sectors, the distance was significantly higher for men (C: p = .048; P1: p = .041, M1: p < .01; M2: p = .034). CONCLUSIONS: Use of the Doppler ultrasound transducer might be a promising approach to non-invasively detect relevant palatine blood vessels preoperatively. It, therefore, might have the potential to reduce the risk of accidental injury during palatal surgery.

Effects of wearing removable dentures and aging on palatal mucosa blood flow by laser doppler.

Aim: The purpose of this work is to analyze the effects of removable dental prostheses and aging on blood microcirculation in the palatal mucosa. Settings and Design: Blood flow was measured in two groups using the Laser Doppler Flowmeter at three specific anatomical sites: Retro incisive papilla, medial raphe, and Schroeder area. Materials and Methods: Group 1 included young, healthy dentulous individuals (mean age: 23 ± 3 years), and Group 2 contained elderly edentulous individuals (mean age: 62 ± 11.69 years). For Group 1, measurements were taken in a single session; for Group 2, the measurements were taken in two sessions: The first just before the prosthetic load (E1) and again 1 week after new dentures were provider (E2). Statistical Analysis Used: Statistical analyses were performed using SAS software, Version 9.4 of the SAS System for Windows, Copyright © 2017 SAS Institute Inc. (Cary, NC, USA). A P < 0.05 was classified as statistically significant. Results: Measurements of blood flow of the palatal mucosa showed that the healthy young dentulous participants had significantly lower perfusion unit values than the elderly edentulous participants at all three anatomical sites (P < 0.05). For Group 2, the comparisons between the measurements taken before (E1) and after (E2) new dentures were provided showed no significant differences. Conclusion: Our results indicate that the process of aging significantly modifies the blood flow of the palatal mucosa while wearing removable dental prostheses does not modify the blood flow of the palatal mucosa in a 1week period. These results are not influenced by systemic pathology (e.g., diabetes, cardiovascular diseases) or smoking.

Identifying the course of the greater palatine artery using intraoral ultrasonography: cohort study.

AIMS: The greater palatine artery (GPA) is one of the most important anatomical structure for free gingival grafts or connective-tissue grafts during soft tissue surgery for dental implants. Several studies have identified the approximate location of the GPA, but it is impossible to detect its exact location during surgery due to large variability between individuals. The authors, therefore, investigated the course of the GPA using intraoral ultrasonography to determine the feasibility of using real-time nonionizing ultrasonography for implant surgery. MATERIALS AND METHODS: This study included 40 healthy young participants. The courses of the GPA were identified using intraoral ultrasound probes from the first premolar to the second molar. The distance from the gingival margin to the GPA (GM-GPA) and the depth of the palatal gingiva from the GPA (PG-GPA) were measured by two independent examiners. Measurements were analyzed statistically, and interexaminer reliability was determined. RESULTS: The distance of the GM-GPA and the mean depth of the PG-GPA were 14.8 ± 1.6 mm and 4.10 ± 0.51 mm (mean ± SD), respectively. GM-GPA decreased when the GPA ran from the second molar to the first molar, and GM-GPA was significantly shorter in females (P < 0.05). PG-GPA increased when the GPA ran to the posterior teeth. Interexaminer measurement agreements were excellent, with intraclass correlation coefficient values of 0.983 and 0.918 for GM-GPA and PG-GPA, respectively. CONCLUSIONS: Using an intraoral ultrasound probe, real-time GPA tracking is possible, which is expected to help reduce the possibility of bleeding during surgery.

The Surgical Anatomy of the Greater Palatine Artery: A Human Cadaver Study.

Identifying the accurate location of the greater palatine artery (GPA) can be challenging. The purpose of the present cadaver study was to determine the location of the GPA from the cementoenamel junction (CEJ) of the maxillary canine to second molar teeth and to define its relationship with the palatal vault height (PVH) in Caucasian cadavers. Sixty-six sections from fully or partially dentate cadavers were examined. The location of the GPA from the CEJ ranged from a minimum of 8.7 ± 2.1 mm at the canine to 14.5 ± 1.3 mm at the second molar. The minimum distance of the GPA to the CEJ in different PVH ranged from 6 to 12 mm. There was a significant difference between male and female cadavers regarding shallow PVH. Only the PVH as an independent variable had a significant correlation with the GPA location. The present study is the first to identify the different PVHs with customized stents and to correlate them with the distance of the GPA to the CEJ of maxillary teeth.

Treatment of deep-seated palatal vascular malformations by bleomycin sclerotherapy.

BACKGROUND: Vascular malformations of the head and neck are common. The management of these lesions is complex and challenging due to the high complication rate and recurrence following treatment. Palatal vascular malformations (PVMs) are infrequent and present as slow growing lesions in the palate with recurrent bleeding and pain. These lesions are best managed by sclerotherapy due to their posterior location and risk of bleeding if surgery is attempted. Many sclerosants have been used for treating PVMs but the use of intralesional bleomycin for these lesions has not been reported at length. This paper describes the use of intralesional bleomycin injections for the treatment of deep-seated palatal vascular malformations. METHODS: Intralesional bleomycin injections were given directly into the lesion with the patients under short general anaesthesia. The total dose of bleomycin ranged between 8 and 15 IU, which depends upon the body weight and was repeated every four weeks till the resolution of lesion was observed. RESULTS: All the lesions in 12 patients regressed significantly with serial bleomycin injections. Clinically, the involved palatal mucosa became normal and magnetic resonance imaging demonstrated the significant regression of the lesion in all the cases. No complications were encountered with the use of intralesional bleomycin. CONCLUSIONS: Intralesional bleomycin injections have proved to be an emerging modality in the management of remotely situated palatal vascular malformations. Their rapid regressive effect on the lesion coupled with a high safety margin makes bleomycin sclerotherapy the first choice of treatment for palatal vascular malformations.

Assessment of Palatal Mucosal Wound Healing Following Connective-Tissue Harvesting by Laser Speckle Contrast Imaging: An Observational Case Series Study.

Postoperative complications may occur during the healing of palatal donor sites due to disturbed blood circulation of palatal tissues. Therefore in this study, blood flow was measured by Laser Speckle Contrast Imaging (LSCI) in seven patients after connective-tissue harvesting. The slope in blood-flow elevation within the first 3 days as well as time needed for maximum reperfusion were calculated. Each surgical site was assessed by clinical examination on day 3. In donor sites with secondary-intention wound healing, postoperative blood flow was elevated with significant delay compared to the surrounding tissues and to the primarily healed wound. Reperfusion time and healing score were strongly correlated (r = 0.87, P < .001), as were the slope and clinical rank (r = -0.85, P < .001). LSCI proved to be an objective method to assess individual wound-healing time and to predict the quality of wound healing.

Contemporary CBCT diagnostics-discovery of a new artery with possible impact on surgical planning: the anterior superior palatal alveolar artery.

PURPOSE: An ongoing clinical trial regarding intra- and post-surgical morbidity in maxillary apicoectomies showed significant higher morbidity for upper canines and palatal roots of upper 1st premolars. Analysis of available presurgical cone beam computed tomography (CBCT)-scans revealed the existence of an unknown bone-canal branching off from the bone-canal or groove of the anterior superior alveolar artery (asaa). Aim of the study was the determination of the contents of this newly found bone canal in human cadaver heads, its prevalence as possible standard anatomical structure and its automatized detection with a contemporary high-resolution TRIUM-CBCT-device in vivo. METHODS: 35 human cadaver heads were dissected, the prevalence of the bone-canal determined and its contents analyzed by histology. 835 consecutive routine high-resolution TRIUM-CBCT-scans from routine patients were analyzed by an automatized detection- and tracing-algorithm for in vivo-determination of prevalence of this bone canal. Automatized detection and additional manual tracing were statistically evaluated by SSPS 20.0 software. RESULTS: The bone-canal was found in 96% of the anatomical specimens, its content identified as artery not described until now and named after the first finder "Arteria Kurrekii". Automatized tracing of TRIUM-CBCT-scans with additional manual tracing revealed an in vivo prevalence of this newly found artery of 95% (p ≤ 0.05). CONCLUSIONS: The newly found anterior superior palatal alveolar artery (aspaa-"Arteria Kurrekii") might have the same clinical impact for surgical procedures in the maxilla as the posterior superior alveolar artery (psaa). Its first detection was enabled by high-resolution TRIUM-CBCT devices and prevalence as standard anatomical structure proven in vivo by automatized CBCT-scan analysis.

Anatomy of the Le Fort I segment: Are arterial variations a potential risk factor for avascular bone necrosis in Le Fort I osteotomies?

PURPOSE: Osteotomies of the Le Fort I segment are routine operations with low complication rates. Ischemic complications are rare, but can have severe consequences that may lead to avascular bone necrosis of the Le Fort I segment. Therefore the aim of this study was to investigate the blood supply and special arterial variants of the Le Fort I segment responsible for arterial hypoperfusion or ischemic avascular necrosis after surgery. MATERIAL AND METHODS: The arterial anatomy of the Le Fort I segment's blood supply using 30 halved human cadaver head specimens was analyzed after complete dissection until the submicroscopic level. In all specimens the arterial variants of the Le Fort I segment and also the arterial diameters measured at two points were evaluated. RESULTS: The typical known vascularization pattern was apparent in 90% of all specimens, in which the ascending palatine (D1: 1,2 mm ± 0,34 mm; D2: 0,8 mm ± 0,34 mm) and ascending pharyngeal artery (D1: 1,3 mm ± 0,58 mm; D2: <0,4 mm) were both supplying the Le Fort I segment. However in 10% of all specimens, the Le Fort I segment was dependent on the ascending pharyngeal artery alone and the missing ascending palatine artery was replaced with the anterior branch of the ascending pharyngeal artery (D1: 1,9 mm ± 0,32; D2: 1,0 mm ± 0,3 mm). CONCLUSION: This study is the first description of a special type of arterial variation of the Le Fort I segment. The type of this arterial variation, its clinical relevance and potential consequences are explained. Individuals with this special arterial anatomy may clinically be at a high risk for hypoperfusion and avascular segment necrosis after surgery. An individualized operation plan may prevent ischemic complications in at-risk patients.

High-resolution dental magnetic resonance imaging for planning palatal graft surgery-a clinical pilot study.

AIM: To evaluate whether high-resolution, non-contrast-enhanced dental magnetic resonance imaging (MRI) can be used for accurate determination of palatal masticatory mucosa thickness (PMMT) and to locate the greater palatal artery (GPA). MATERIALS AND METHODS: In five volunteers (four males, one female; mean age 30.2 ± 0.4 years), two independent raters measured PMMT by use of dental MRI in 180 positions. For comparison, clinical bone sounding was performed. The GPA was identified in time-of-flight (TOF) angiography and MSVAT-SPACE-prototype sequence. Intra- and inter-observer agreement for MRI measurements, agreement between MRI and bone sounding were analysed by intra-class correlation coefficient (ICC) and Cohen's kappa (κ). RESULTS: Reliability of dental MRI measurements was high (intra-observer-ICC 0.962; inter-observer ICC 0.959). Agreement of MRI measurements with bone sounding was moderate (ICC 0.744), and the GPA could be identified in 60% of measurement points using the TOF-angiography alone and in 85% with additional information of the MSVAT-SPACE. Good intra-observer agreement was observed for GPA identification (κ: 0.778). CONCLUSION: Palatal masticatory mucosa thickness measured by high-resolution, non-contrast enhanced dental MRI is comparable with that obtained by bone sounding. Dental MRI enables reliable, non-invasive and radiation-free planning of palatal tissue harvesting and can also be used for location of the GPA at 85% of measurement points, which might help reduce complications during surgery.

Endoscopic sphenopalatine artery ligation for acute idiopathic epistaxis. Do anatomical variation and a limited evidence base raise questions regarding its place in management?

BACKGROUND: Endoscopic sphenopalatine artery ligation is widely accepted as effective and safe for acute spontaneous epistaxis that is unresponsive to conservative management. As with many new procedures, it has been progressively adopted as common practice, despite a limited evidence base for its efficacy. Early reviews called for comparative trials to support its adoption, but subsequent literature largely consists of case series and narrative reviews. These have attempted to derive an algorithm to establish its place in management, but consensus is still lacking. Intuitively, although there are theoretical objections, an operation regarded as relatively simple, fast and safe hardly seems to demand high-level evidence of efficacy. Rhinologists may be influenced by years of personal experience and success with the technique. However, estimates of the effect size and the added contribution to traditional surgical management are lacking. If the procedure could be shown to dramatically influence outcome, it should be standard practice and indispensable for all patients requiring operative intervention. OBJECTIVES: This paper systematically examined the literature, appraising the anatomical basis for such an approach and evidence for its efficacy. It questions whether any units unable to consistently offer endoscopic sphenopalatine artery ligation should be undertaking surgical management of acute epistaxis.

Epinephrine Affects Pharmacokinetics of Ropivacaine Infiltrated Into Palate.

Pulpal anesthesia success rates for ropivacaine following maxillary infiltration anesthesia seem to be low. We investigated the hypothesis that the addition of epinephrine would affect the pharmacokinetics of ropivacaine by retaining ropivacaine in the mucosa of the injected area through the time-dependent distribution of ropivacaine in the rat maxilla and serum following maxillary infiltration anesthesia using (3)H-labeled ropivacaine. We then examined the vasoactivity of ropivacaine with or without epinephrine on local peripheral blood flow. The addition of epinephrine to ropivacaine increased ropivacaine concentrations in the palatal mucosa and adjacent maxilla by more than 3 times that of plain ropivacaine at 20 minutes. By observing the autoradiogram of (3)H-ropivacaine, plain ropivacaine in the maxilla was remarkably reduced 20 minutes after injection. However, it was definitely retained in the palatal mucosa, hard palate, adjacent maxilla, and maxillary nerve after the administration with epinephrine. Ropivacaine with epinephrine significantly decreased labial blood flow. This study suggests that 10 µg/mL epinephrine added to 0.5% ropivacaine could improve anesthetic efficacy and duration for maxillary infiltration anesthesia over plain ropivacaine.

Pilot Study of Laser Doppler Measurement of Flow Variability in the Microcirculation of the Palatal Mucosa.

Background. Histopathological alterations can arise when the denture-supporting mucosa experiences microbial and mechanical stress through the denture base and diagnosis of these diseases usually follows microvascular changes. Microcirculation measurement could allow for detection of such dysfunction and aid in the early diagnosis of palatal mucosa pathologies. Materials and Methods. We tested the sensitivity of laser Doppler for measuring the microcirculation of the palatal mucosa, assessing the median raphe (MR), Schroeder area (SA), and retroincisive papilla (RP). A Doppler PeriFlux 5000 System, containing a laser diode, was used. 54 healthy participants were recruited. We compare the measurements of PU (perfusion unit) using ANOVA test. Results. The numerical values for palatal mucosa blood flow differed significantly among the anatomical areas (p = 0.0167). The mean value of Schroeder area was 92.6 (SD: 38.4) and was significantly higher than the retroincisive papilla (51.9) (SD: 20.2) (p < 0.05), which in turn was higher than that of median raphe (31.9) (SD: 24.2) (p < 0.0001). Conclusion. Schroeder area appeared to have the greatest sensitivity, and vascular flow variability among individuals was also greatest in this region. We suggest that analysis of blood stream modification with laser Doppler of the palatal mucosa can help to detect onset signs of pathological alterations.

Sphenopalatine Artery Ligation for Epistaxis: Factors Influencing Outcome and Impact of Timing of Surgery.

OBJECTIVE: Sphenopalatine artery ligation is a commonly employed surgical intervention for control of posterior epistaxis unresponsive to nasal packing. The objective of the present study was to evaluate the outcome of sphenopalatine artery ligation for control of epistaxis at our institution and the impact of timing and other factors on outcome. STUDY DESIGN: Case series with chart review. SETTING: Academic tertiary referral center. SUBJECTS AND METHODS: Case notes were reviewed for 45 consecutive patients undergoing sphenopalatine artery ligation for control of epistaxis between October 2008 and October 2014. RESULTS: Forty-one patients had nasal packing prior to sphenopalatine artery ligation, with 33 undergoing ≥2 packings. Postoperatively, 6 patients had rebleeding, which was treated with repacking (n = 4) and return to the operating room (n = 2). The overall success rate of sphenopalatine artery ligation was 87% (39 of 45). Rebleeding rate was not affected by concomitant septoplasty, anterior ethmoidal artery ligation, or postoperative nasal packing. Patients undergoing SPA ligation within the first 24 hours of admission had a significantly shorter hospital length of stay (3 vs 6 days, P = .02) and treatment cost (€5905 vs €10,001, P = .03). Length of stay was not influenced by sphenopalatine artery ligation after ≤1 nasal pack versus ≥2 packs. Timing of sphenopalatine artery ligation did not affect blood transfusion requirement (P = .84). CONCLUSION: Sphenopalatine artery ligation is an effective management strategy for surgical control of refractory epistaxis. Early timing of sphenopalatine artery ligation may lead to reductions in length of stay.

U-shaped Osteotomy Around the Descending Palatine Artery to Prevent Posterior Osseous Interference for Superior/Posterior Repositioning of the Maxilla in Le Fort I Osteotomy.

In maxillary orthognathic surgery, superior repositioning of the maxilla is sometimes difficult, and removal of bony interference, especially around the descending palatine artery (DPA), is very time-consuming in cases of severe maxillary impaction. Posterior repositioning of the maxilla for removal of bony interference between the posterior maxilla and the pterygoid process is also technically difficult. Because the most common site of hemorrhage in Le Fort I osteotomy is the posterior maxilla, this bone removal is a source of frustration for surgeons in DPA injury. When the DPA is injured during bone removal and ligation is performed, aseptic necrosis of the maxilla may occur. Therefore, a simple and safe method for maxillary superior/posterior repositioning is required to remove osseous interference around the DPA. The authors describe here U-shaped osteotomy around the DPA to prevent posterior osseous interference for superior/posterior repositioning of the maxilla in Le Fort I osteotomy.

Rapid palatal expansion: the role of microcirculation.

AIM: Transverse palate modifications fall under expansive orthopedic therapy of the upper maxilla. The only practical approach to the problem on the transverse plane is that of performing the expansion of the maxillary arch through an opening of the median palatal suture. It is important to understand the changes of the vascular network in midpalatal suture following the starting of rapid maxillary expansion. It is critical to maintain the blood supply and circulation for the osteogenesis and bone remodeling after the expansion. The aim of this research was to evaluate the effects of rapid orthopedic expansion (REP) at the microcirculatory level through capillaroscopic examination. METHODS: Fifteen patients in their developing years between 9 and 15 years of age (average age 12.16 years) were examined. The application of the REP was the first step in the planning of orthopedic-orthodontic treatment which foresaw further stages in the odonto-osseous movement. The method of Biomicroscopic Video-Imaging of the microcirculation of oral mucosa is performed through the technique of computerized capillaroscopy and the related software. RESULTS: From the results it is evident that immediately after achieving the expansion of the upper maxilla (t1), a slight decrease in the number of vessels per mm² can be observed. In addition, a slight ectasia can be observed in these vessels in comparison to t0. Comparing the videocapillaroscopic images of t1 and t2, an increase in the capillaries per mm² can be observed. CONCLUSION: Ectasia of the capillaries, though subject to strictly individual variables, can be considered perfectly normal and it is compatible with the normal biology and physiology of vessel microcirculation.

Percutaneous Treatment of Large Venous Malformations in the Oral and Maxillofacial Regions Using Electrochemical Therapy Combined With Pingyangmycin.

PURPOSE: The aim of the present study was to evaluate the therapeutic outcome of using electrochemical therapy (ECT) combined with a sclerosing agent, pingyangmycin (bleomycin A5 hydrochloride; PYM), for large (>3 cm in diameter) venous malformations (VMs) in the oral and maxillofacial regions. PATIENTS AND METHODS: Thirty-five patients (15 male and 20 female; age range, 10 to 69 yr; mean age, 32 yr) with large VMs in the oral and maxillofacial region were treated with a combination of ECT and PYM under general anesthesia in the authors' department from June 2012 through May 2014. The size of the lesions varied from 3 × 3 to 12 × 15 cm. A repeated course of ECT and PYM was administered for larger VMs. The therapeutic interval was 3 months for ECT and 2 to 4 weeks for PYM. The dose of PYM for patients was 8 mg each time, and the injection concentration of PYM was 1.6 mg/mL. Patients were followed for 6 to 36 months. Therapeutic results were evaluated by clinical examination and Doppler ultrasonography before and after treatment. RESULTS: Of the 35 patients, 29 (82.9%) received 1 ECT treatment, 5 (14.3%) received 2 ECT treatments, and 1 (2.8%) received 3 ECT treatments. The number of PYM injection sessions was 1 to 5 (average, 2.5 times). According to the therapeutic criteria, the clinical outcome was excellent in 22 patients (62.9%), good in 10 patients (28.6%), and fair in 3 patients (8.5%). All patients (100%) had local swelling postoperatively that lasted approximately 1 to 2 weeks. Two patients (5.7%) had fever. No skin necrosis or nerve damage was found. CONCLUSIONS: Percutaneous treatment using ECT and PYM was a straightforward, safe, and reliable treatment modality for large VMs.

Three-dimensional computed tomographic evaluation of bilateral sagittal split osteotomy lingual fracture line and le fort I pterygomaxillary separation in orthognathic surgery using cadaver heads: ultrasonic osteotome versus conventional saw.

PURPOSE: The purpose of this study was to observe the quality of the fracture line on the lingual side of the mandible after sagittal split osteotomy and the quality of pterygomaxillary separation after Le Fort I osteotomy using the BoneScalpel ultrasonic osteotome. MATERIALS AND METHODS: Bimaxillary procedures, according to the standard protocol, were performed using 10 fresh cadaver heads. The ultrasonic osteotome was used in the study group, and a reciprocating saw was used in the control group. Three-dimensional reconstructions of postoperative computed tomographic scans were obtained. The lingual ramus fracture pattern and the pterygomaxillary separation pattern were observed, classified, and compared. Postoperative dissections of the skulls were performed to assess the integrity of the infra-alveolar nerve and the descending palatine artery. RESULTS: No significant differences were found in the cutting time of bone between the BoneScalpel and the sagittal saw. Of the sagittal split osteotomies in the study group, 90% showed a good pattern (vertical pattern of fracture line extending to the inferior border of the mandible running behind the mandibular canal) compared with 50% of the sagittal split osteotomies in the control group. Ideal separation of the pterygoid plates without fractures was observed in 80% of the Le Fort I osteotomies in the study group compared with 50% of the osteotomies in the control group. High-level fractures occurred in 30% of cases in the control group compared with none in the study group. The integrities of the infra-alveolar nerve and the descending palatine artery were preserved in all cases. CONCLUSION: Use of the ultrasonic BoneScalpel did not require more time than the conventional method. An improved pattern of lingual fracture lines in mandibular sagittal split osteotomy procedures and the pattern of pterygomaxillary separation in Le Fort I osteotomy procedures were observed.

Vascularization of the gray whale palate (Cetacea, Mysticeti, Eschrichtius robustus): soft tissue evidence for an alveolar source of blood to baleen.

The origin of baleen in mysticetes heralded a major transition during cetacean evolution. Extant mysticetes are edentulous in adulthood, but rudimentary teeth develop in utero within open maxillary and mandibular alveolar grooves. The teeth are resorbed prenatally and the alveolar grooves close as baleen germ develops. Arteries supplying blood to highly vascularized epithelial tissue from which baleen develops pass through lateral nutrient foramina in the area of the embryonic alveolar grooves and rudimentary teeth. Those vessels are hypothesized to be branches of the superior alveolar artery, but branches of the greater palatine arteries may play a role in the baleen vascularization. Through a combination of latex injection, CT, and traditional dissection of the palate of a neonatal gray whale (Eschrichtius robustus), we confirm that the baleen receives blood from vessels within the superior alveolar canal via the lateral foramina. The greater palatine artery is restricted to its own passage with no connections to the baleen. This study has implications for the presence of baleen in extinct taxa by identifying the vessels and bony canals that supply blood to the epithelium from which baleen develops. The results indicate that the lateral foramina in edentulous mysticete fossils are bony correlates for the presence of baleen, and the results can be used to help identify bony canals and foramina that have been used to reconstruct baleen in extinct mysticetes that retained teeth in adulthood. Further comparisons are made with mammals that also possess oral keratin structures, including ruminants, ornithorhynchid monotremes, and sirenians.

Anatomical study of the pterygomaxillary area for implant placement: cone beam computed tomographic scanning in 100 patients.

PURPOSE: The aim of this study was to describe the average angulation and dimensions of the pterygomaxillary area in the atrophic maxilla to facilitate the orientation of pterygoid implants during their placement. MATERIALS AND METHODS: A retrospective radiologic study was made. A virtual pterygoid implant, 13, 15, or 18 mm long, was placed in the pterygomaxillary area following the axis of the bone, with a distance of at least 2 mm maintained between the artery and palatine nerve and the implant. The long axis of the implant was inclined slightly toward the palatal to follow the cortical palatal bone. The angles between the long axis of the virtual implant and Frankfort horizontal were measured in both sagittal and frontal views. To calculate the average length of the pterygomaxillary area, the virtual long axis of the implant was measured from the alveolar crest to the pterygomaxillary suture. RESULTS: The average anteroposterior axis inclination of the pterygomaxillary area was 72.5 ± 4.9 degrees relative to Frankfort horizontal. The average angulation of the palatal vestibule was 81.3 ± 42.8 degrees relative to Frankfort horizontal. The average length of the pterygomaxillary area was 22.5 ± 4.8 mm. CONCLUSION: Pterygoid implant placement requires thorough knowledge of each patient's anatomy and individual needs. The mean position of the pterygomaxillary buttress axis was 72.5 ± 4.9 degrees to the distal and 81.3 ± 2.8 degrees to the palatal relative to Frankfort horizontal. Placement of pterygoid implants in this inclination may increase accuracy of implant placement. The average length from the tuberosity to the most apical point of the pterygoid apophysis was 22.5 ± 4.8 mm. These results suggest that an implant 15 to 18 mm in length would fit in the pterygomaxillary area to reach the cortical bone.