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Concept: Maxilla

196

Razanandrongobe sakalavae Maganuco, Dal Sasso & Pasini, 2006 is a large predatory archosaur from the Middle Jurassic (Bathonian) of the Mahajanga Basin, NW Madagascar. It was diagnosed on the basis of teeth and a fragmentary maxilla, but its affinities were uncertain. Here we describe new cranial remains (above all, an almost complete right premaxilla and a caudally incomplete left dentary) that greatly improve our knowledge on this enigmatic species and reveal its anatomy to be crocodylomorph. The right premaxilla indicates that the rostrum was deep, wide, and not pointed; it bears five teeth that are sub-vertical and just slightly curved lingually; the mesial teeth are U-shaped in cross-section and have serrated carinae on the lingual side; the aperturae nasi osseae (external bony nares) are confluent and face rostrally; and there is no lateral groove at the premaxillomaxillary suture for reception of a hypertrophied lower caniniform tooth. The preserved portion of the left dentary has an edentulous tip and bears eight large mandibular teeth of which the mesial (1-3) are the largest, but none is a hypertrophied caniniform tooth; the mandibular (dentary) symphysis extends caudally to the level of the third tooth; the splenial is not preserved, but its sutural marks on the dentary indicate that it contributed to the mandibular symphysis for at least 20% of the symphyseal length in dorsal aspect. On the basis of this new data, some previously uncertain features of the holotype maxilla-such as the margin of the suborbital fenestra, the contact surfaces for the palatine, the ectopterygoid, and the jugal-are now apparent. Testing of the phylogenetic position of the species within Crocodylomorpha indicates that R. sakalavae is a mesoeucrocodylian. It also represents one of the earliest events of exacerbated increase in body size along the evolutionary history of the group. In addition, it is by far the oldest notosuchian. A cranial reconstruction of this gigantic predator is also attempted here. The very robust jaw bones of R. sakalavae, coupled with its peculiar dentition, strongly suggest a diet that included hard tissue such as bone and tendon.

Concepts: Left-wing politics, Mandible, Teeth, Animal anatomy, Jaw, Maxilla, Symphysis menti, Symphysis

168

The aim of this study was to quantify anteroposterior facial soft tissue changes with respect to underlying skeletal movements after Le Fort I maxillary advancement and mandibular setback surgery with sagittal split osteotomy in Class III skeletal deformity by using lateral cephalograms taken before and after the operation. The material consisted of 31 patient (15 female, 16 male cases, mean age was 26.7 ± 2.5 years) with Class III skeletal deformity. All patients were treated by Le Fort I maxillary advancement and mandibular setback surgery with sagittal split osteotomy. Lateral cephalograms were taken before and 1.4 ± 0.3 years after surgery. Wilcoxon test was used to compare the pre- and post-surgical measurements. Pearson correlation test was used to compare the relationships between the skeletal, dental and facial soft tissue changes. In the maxilla, the APOINTAP (the anteroposterior position of A point) and ITIPAP (the anteroposterior position of upper incisor) showed significant protractions (-3.19 ± 3.63, and -3.19 ± 4.52, p < 0.01). In the mandible, the L1TIPAP (the anteroposterior position of lower incisor, -3.20 ± 5.83, p < 0.01), L1TIPSI (the superoinferior position of lower incisor, -2.43 ± 10.31, p < 0.05), BPOINTSP (the superoinferior position of B point, -2.28 ± 12.51, p < 0.05) and BPOINTAP (the anteroposterior position of B point, -3.19 ± 9.31, p < 0.01) showed significant retractions and upper positions after bimaxillary surgery. The insignificant decrease in soft tissue Pog-Vert distance was correlated the significant upper position of B point and lower incisor (r: 0.851, p < 0.001 and r: 0.842, p < 0.001).

Concepts: Spearman's rank correlation coefficient, Mandible, Tissues, Correlation and dependence, Pearson product-moment correlation coefficient, Soft tissue, Karl Pearson, Maxilla

145

In the present report, we describe the successful use of miniscrews to achieve vertical control in combination with the conventional sliding MBT™ straight-wire technique for the treatment of a 26-year-old Chinese woman with a very high mandibular plane angle, deep overbite, retrognathic mandible with backward rotation, prognathic maxilla, and gummy smile. The patient exhibited skeletal Class II malocclusion. Orthodontic miniscrews were placed in the maxillary anterior and posterior segments to provide rigid anchorage and vertical control through intrusion of the incisors and molars. Intrusion and torque control of the maxillary incisors relieved the deep overbite and corrected the gummy smile, while intrusion of the maxillary molars aided in counterclockwise rotation of the mandibular plane, which consequently resulted in an improved facial profile. After 3.5 years of retention, we observed a stable, well-aligned dentition with ideal intercuspation and more harmonious facial contours. Thus, we were able to achieve a satisfactory occlusion, a significantly improved facial profile, and an attractive smile for this patient. The findings from this case suggest that nonsurgical correction using miniscrew anchorage is an effective approach for camouflage treatment of high-angle cases with skeletal Class II malocclusion.

Concepts: Torque, Mandible, Horse, Teeth, Malocclusion, Orthodontics, Maxilla, Prognathism

28

BACKGROUND: New implant designs are continuously introduced to the market. It is important to evaluate and report on their clinical performance when used in everyday practice. PURPOSE: The aim of the present study was to evaluate the clinical performance of a novel hydrophilic dental implant for 1 year. MATERIALS AND METHODS: A total of 49 patients previously treated with 102 hydrophilic dental implants (Neoss Proactive, Neoss Ltd, Harrogate, UK) were retrospectively evaluated with regard to survival rate and marginal bone loss. Fifty-four implants were installed in maxillae and 48 in mandibles to replace single teeth (n = 21), to support partial bridges (n = 26), total maxillary bridges (n = 2), or mandibular overdentures (n = 2). The majority of patients (n = 37) had implants placed in healed sites without any adjunctive procedures. In 12 patients, implants were immediately placed in extraction sockets or in conjunction with maxillary sinus floor augmentation. All implant sites had been classified according to the Lekholm and Zarb index. Baseline and 1-year intraoral radiographs were used to calculate marginal bone levels and bone loss. Implant stability quotient (ISQ) measurements had been taken at placement and after 3 to 4 months of healing RESULTS: The implants became rapidly covered with blood at the first contact. One implant was lost, giving a cumulative survival rate (CSR) of 99.0% after 1 year. The marginal bone loss amounted to 0.7 ± 0.6 mm with 3.5% of the implants showing more than 2 mm of bone loss and no implant more than 3 mm bone loss after 1 year. The primary stability was found to be 72.7 ± 7.5 ISQ, which slightly increased to 73.6 ± 7.2 ISQ (NS) after 3 to 4 months of healing. The stability was significantly higher in the mandible than in the maxilla at placement and after healing. CONCLUSION: In this limited clinical study, the use of a novel hydrophilic dental implant results in favorable short-term outcomes.

Concepts: Mandible, Implants, Dental implant, Titanium, Dentistry, Osseointegration, Implant stability quotient, Maxilla

28

The early treatment of Class III malocclusion with a protraction facemask can produce forward movement of the maxilla but is generally associated with posterior rotation of the mandible and dentoalveolar compensations. This article shows the dental and skeletal effects of intermaxillary elastics applied to temporary anchorage devices in the treatment of maxillary deficient Class III patients.

Concepts: Mouth, Maxilla, Dental anatomy, Sanskrit, Bones of the head and neck, Dental consonant

27

A new basal hadrosauroid dinosaur from the Lower Cretaceous Khok Kruat Formation of Thailand, Sirindhorna khoratensis gen. et sp. nov is described. The new taxon is based on composite skull and mandible including premaxilla, maxilla, jugal, quadrate, braincases, predentary, dentaries, surangular, and maxillary and dentary teeth. It is diagnostic by such characters as, sagittal crest extending along entire dorsal surface of the parietal and reaching the frontoparietal suture (autapomorphy), transversely straight frontoparietal suture, caudodorsally faced supraoccipital, no participation of the supraoccipital in the foramen magnum, mesiodistally wide leaf-shaped dentary tooth with primary and secondary ridges on the lingual surface of the crown, perpendicularly-erected and large coronoid process of dentary, and nonvisible antorbital fossa of the maxilla in lateral view. Phylogenetic analysis revealed S. khoratensis as among the most basal hadrosauroids. Sirindhorna khoratensis is the best-preserved iguanodontian ornithopod in Southeast Asia and sheds new light to resolve the evolution of basal hadrosauriforms.

Concepts: Mandible, Skull, Thailand, Animal anatomy, Maxilla, Dental anatomy, Isan, Nakhon Ratchasima

27

Treacher Collins syndrome is a disorder characterized by various congenital soft tissue anomalies involving hypoplasia of the zygoma, maxilla, and mandible. A variety of treatments have been reported to date. These treatments can be classified into 2 major types. The first type involves osteotomy for hard tissue such as the zygoma and mandible. The second type involves plastic surgery using bone grafting in the malar region and soft tissue repair of eyelid deformities. We devised a new treatment to comprehensively correct hard and soft tissue deformities in the upper half of the face of Treacher Collins patients. The aim was to “change facial features and make it difficult to tell that the patients have this disorder.” This innovative treatment strategy consists of 3 stages: (1) placement of dermal fat graft from the lower eyelid to the malar subcutaneous area, (2) custom-made synthetic zygomatic bone grafting, and (3) Z-plasty flap transposition from the upper to the lower eyelid and superior repositioning and fixation of the lateral canthal tendon using a Mitek anchor system. This method was used on 4 patients with Treacher Collins syndrome who had moderate to severe hypoplasia of the zygomas and the lower eyelids. Facial features of these patients were markedly improved and very good results were obtained. There were no major complications intraoperatively or postoperatively in any of the patients during the series of treatments. In synthetic bone grafting in the second stage, the implant in some patients was in the way of the infraorbital nerve. Thus, the nerve was detached and then sutured under the microscope. Postoperatively, patients had almost full restoration of sensory nerve torpor within 5 to 6 months. We devised a 3-stage treatment to “change facial features” of patients with hypoplasia of the upper half of the face due to Treacher Collins syndrome. The treatment protocol provided a very effective way to treat deformities of the upper half of the face in patients with Treacher Collins syndrome.

Concepts: Syndromes, Oral and maxillofacial surgery, Eyelid, Maxilla, Levator palpebrae superioris muscle, Treacher Collins syndrome, Zygomatic bone

26

Abstract Aim: To accurately portray the risk management of a patient presenting with mandibular osteonecrosis following bisphosphonate exposure and immediate loading of dental implant treatment. This case report describes a 58-year-old African American female having experienced previous success of implant osseointegration in the maxilla, sought similar mandibular treatment four years later and had been taking bisphosphonate for a total 5 years. All existing mandibular teeth were extracted and 6 Brånemark System implants were placed and immediately loaded without complication. Two weeks postoperative, a slower rate of healing was noticed. Over a period of six weeks, the patient’s condition worsened. An extraoral fistula exuded from a lesion on the left inferior border of the mandible. The patient was diagnosed with bisphosphonate-induced osteonecrosis of the jaw (BONJ) and discontinued bisphosphonate medication indefinitely. The patient was treated for BONJ and four of the six implants which were encapsulated in tissue were removed. She ceased the oral Fosamax therapy for two and a half years following the BONJ, and had morning-fasting serum C-terminal telopeptide (CTX) test of 457 pg/ml* which showed her bone turnover rate had returned to normal levels. Four new Brånemark System implants were placed in the mandible and were immediately loaded. Four months later, a screw-retained implant-supported final prosthesis was delivered. The patient has been followed for 5 years from the time of retreatment of mandibular arch and 11 years from time of implant placement in the maxillary arch. All postoperative evaluations have been uneventful. This case report demonstrated how management of BONJ can lead to successful retreatment with implants after a drug holiday, and how being cognizant to the length of time of Fosamax therapy can help clinicians avoid BONJ complications.

Concepts: Bone, Mandible, Implants, Prosthetics, Dental implant, Osseointegration, Jaw, Maxilla

25

Sinus floor elevation via the lateral window approach represents a reliable technique for bone augmentation in the atrophic posterior maxilla. It is known that sinus membrane elevation leads to new bone formation. This prospective clinical study compared a specific technique in sinus membrane elevation with a conventional sinus floor augmentation (xenogenous/autogenous bone) in a human split mouth model.

Concepts: Clinical trial, Human, Sinusitis, Human anatomy, Posterior superior alveolar artery, Maxillary sinus, Maxilla, Inferior nasal concha

17

The cranial and postcranial anatomy of the basal hadrosaurid dinosaur Eotrachodon orientalis, from the uppermost Santonian of southern Appalachia (southeastern U.S.A.), is described in detail. This animal is the only known pre-Campanian non-lambeosaurine hadrosaurid, and the most complete hadrosauroid known from Appalachia. E. orientalis possesses a mosaic of plesiomorphic and derived characters in the context of Hadrosauroidea. Characters shared with basal hadrosauroids include a short and sloping maxillary ectopterygoid shelf, caudally prominent maxillary jugal process, one functional tooth per alveolus on the maxillary occlusal plane, a jugal rostral process with a shallow caudodorsal margin and medioventrally facing articular facet, a vertical dentary coronoid process with a poorly expanded apex, and tooth crowns with accessory ridges. Derived characters shared with other hadrosaurids include a circumnarial depression compartmented into three fossae (as in brachylophosaurins and Edmontosaurus), a thin everted premaxillary oral margin (as in Gryposaurus, Prosaurolophus, and Saurolophus), and a maxilla with a deep and rostrocaudally extensive rostrodorsal region with a steeply sloping premaxillary margin (as in Gryposaurus). Eotrachodon orientalis differs primarily from the other hadrosauroid from the Mooreville Chalk of Alabama, Lophorhothon atopus, in having a slender and crestless nasal whose caudodorsal margin is not invaded by the circumnarial depression. Hadrosaurus foulkii, the only other known hadrosaurid from Appalachia, is distinct from E. orientalis in having dentary teeth lacking accessory ridges and a dorsally curved shaft of the ischium. A histological section of the tibia of the E. orientalis holotype (MSC 7949) suggests that this individual was actively growing at the time of death and, thus, had the potential to become a larger animal later in development.

Concepts: Maxilla, Dinosaur, Hadrosaurid, Edmontosaurus, Hadrosaurus, Saurolophus, Prosaurolophus, Gryposaurus