Lower Facial Area Research Articles

The Influential Bony Factors and Vectors for Predicting Soft Tissue Responses After Orthognathic Surgery in Mandibular Prognathism

We sought to identify the hard tissue points and vectors that have the greatest effect on soft tissue movement after orthognathic surgery in patients with mandibular prognathism. The present retrospective study involved patients who had undergone mandibular setback surgery with or without maxillary advancement. Multiple linear regression models were adapted to evaluate the association between the 8 hard tissue landmark (predictor variables) changes and 11 soft tissue responses (outcome variables) using the x and y coordinates assessed from superimposed pre- and postoperative 3-dimensional computed tomography images. A total of 50 patients (42 patients had undergone 2-jaw surgery; 8 patients had undergone 1-jaw surgery; mean age 23±4years) were included in the present study. Our statistical models demonstrated that the horizontal hard tissue changes had a greater influence on the soft tissue responses than did the vertical changes, and these changes were more notable in the lower facial area (lower lip contour and chin profile) than the midfacial area (nasal profile, upper lip contour, upper lip length, and nasolabial angle). In the horizontal soft tissue response model, the soft tissue A point/A point ratio was 0.86:1 (95% confidence interval [CI] 0.674-1.049); the soft tissue B point/B point ratio was almost 1:1 (95% CI 0.919-1.071); and the soft tissue pogonion/pogonion ratio was 0.88:1 (95% CI 0.805-0.963). Horizontal or vertical bone tissue changes affected both the horizontal and vertical soft tissue changes in most areas. Our study demonstrated that the soft tissue response is not linear but a more complicated and dynamic reaction.

Effect of dexmedetomidine on perfusion of free flaps transferred to head and neck

The paper presents the impact of perioperative care on feasibility of free fibula flap transfer for facial reconstruction. Flaps vitality was measured by means of somatic oximetry in 85 patients aged 20-74 years receiving reconstruction procedures in midfacial and lower facial areas. The patients were divided in three groups according to sedation agent used postoperatively. It has been demonstrated that dexmedetomidine postoperative sedation significantly improved free fibula flaps perfusion compared to propofol sedation.

An Ultra Low Noise Optoelectronic Module Enables an in Situ Range-Finder Probe to Locate a Neurovascular Bundle in Dental Implant Surgery

Dental implantology procedures necessitate surgical drilling of a hole in the jawbone to insert an artificial root over which a dental prosthesis is placed. The success factor of a dental implant is attaining successful osseointegration. This implies a deeper placed implant closest to the Inferior Alveolar Nerve (IAN) but not too close that it carries the risk of damaging this nerve-artery bundle located along the mandible line. Implications for perforating the IAN in patients can vary from temporary numbness to permanent loss of sensation in the lower facial area. Surgeons routinely use computer-assisted navigation techniques relying on static preoperative cone-beam X-ray computed tomography or other imaging methods such as Magnetic Resonance Imaging (MRI) to assess optimal anatomical distances in the patient’s jaw. However, variability of the measured IAN bundle position with these techniques is at the moment accurate to 30% at best. These techniques are known to introduce localization errors and do not benefit from in situ guidance. Therefore there is an important need for an online, in vivo probe to assess drill distances to a critical nerve-artery bundle in situ to not only avoid jaw paralysis but to improve overall outcome of the implantation.To this aim, we investigate a combined multimodal approach using Optical Coherence Tomography (OCT) for high resolution structural imaging, and functional NIR absorption detection in an optical fiber probe eventually small enough to fit into a surgical drill bit, for real-time evaluation of the distance from the probe to the IAN. We designed a reflectance fiber-optic probe to sense the pulsation of the artery (Heartbeat ~1-2Hz) in the IAN bundle, and a detection circuit board with a high gain (2 . 106 V/A), and very low noise (10mVRMS at output) and bandwidth (10Hz) shown on Figure 1.The success of this NIR channel for accurate real-time proximity sensing by capturing low frequency pulsing signals relies on an ultra low noise photon detection module. Measurements with this fiber probe were conducted at probe-target distances varying from 0mm (probe in contact) to 3mm. The results obtained are promising: the oscillating RMS amplitude varies as a function of distance in a similar fashion to previously published work in pulse oximetry literature [1]. The DC level also has a specific trend as a function of distance. Both AC and DC signal components can be used to extract useful distance information.Original designs using a lock-in amplifier to measure the very low RMS amplitude of the of the back-reflected light intensity, modulated by the spatially oscillating absorption changes due to flowing blood surrogate in an artery simulating tube were promising, but limited.Lock-in signal detection with a reference signal modulated at only 1-2 Hz needs filtering with long time constants. Moreover, clinical implementation with the heartbeat as the reference signal would make real-time measurement impractical. As such, we have developed a flexible optoelectronic detection platform with tunable bandwidth, gain and bias enabling the system to not be limited by electronics noise.Using custom phantoms of the jawbone and including a surrogate arterial dynamic pumping circuit, we demonstrated proof of concept for potential detection range of 0.5-4 mm at l-850nm with a source-detector separation of 1.8mm using the pulsating signal from an artery simulating tube. In compliment, a swept-source OCT at 1.3mm provided finer resolution sensitivity to the proximity of the IAN bundle in the 0-0.9mm range and offered the possibility of imaging the inhomogeneous IAN interface.Methods for calibrating and processing the data to provide robust long range NIR finding capabilities in combination with short-range high precision OCT imaging towards a complete clinical solution will be discussed.

Reappraisal of Using Platysma Myocutaneous Flap for Lower Facial Reconstructions

Miscellaneous methods have been proposed for reconstruction at the lower facial area. Platysma myocutaneous flap seems to be suitable because of its good color match, thinness and pliability of the skin flap. However, it has been underestimated after free flap presented. The purpose of this study is to review the viability and reliability of the platysma flap for lower facial reconstruction in our experience. A retrospective review of 33 patients undergoing platysma flap for lower facial reconstruction from 1990 to 2005 in NTUH was conducted. All patients had acceptable aesthetic and functional results after flap reconstruction. Platysma flap is a viable and reliable method for lower facial reconstruction not only after malignancy ablation surgery but also for other lesions, including scar contracture after corrosive injury, post-irradiation fistula, and noma. It provides excellent cosmetic and functional outcomes with acceptable complications.

A Case of Periocular Necrotizing Fasciitis of Odontogenic Origin

Purpose: We report a case of periocular necrotizing fasciitis originating from dontogenic infection. Case summary: A 53-year-old man, who had suffered from severe periodontitis one week prior, visited our clinic due to a 2-day history of rapidly progressing left mandibular and periorbital swelling and pain. By the time of his visit, he had lost vision in the left eye and had moderate swelling, expression of pus, and skin explosion with necrotizing discoloration of the left lid and lower facial area. MRI of the orbits revealed soft tissue necrosis, gas accumulation, and subperiosteal abscess formation of the left orbit. We administered systemic antibiotics and surgically excised the left periorbital necrotic tissue. A constant expression of pus material was also achieved, decreasing painful swelling. We considered exenteration of the left eye to block the spread of necrosis to adjacent intact tissue; however, the left eye was fairly well-preserved with the exception of mild lagophthalmos developed by the excision of necrotic skin. Streptoccocal species was observed in microbiologic cultures of pus and necrotic tissue and ‘necrotizing inflammation’ was described on tissue biopsy, with the findings consistent with necrotizing fasciitis. Conclusions: Through the diagnosis of necrotizing fasciitis originating from an odontogenic infection, the proper administration of antibiotics and surgical management were achieved. As a result, we were able to preserve the eye. J Korean Ophthalmol Soc 49(6):993-999, 2008

Intracortical inhibition and facilitation in human facial motor area: difference between upper and lower facial area

Objective: To investigate the intracortical inhibitory and excitatory systems in the motor cortical representation of upper and lower facial muscles. Methods: Paired-pulse transcranial magnetic stimulation (TMS) was applied to 7 healthy volunteers, with the interstimulus interval (ISI) between the conditioning stimulus (CS) and test stimulus, varied from 1 to 20 ms. CS was set at 90% of motor threshold. Muscle evoked potentials (MEPs) were recorded from first dorsal interosseus (FDI), orbicularis oculi (o. oculi) and mentalis muscles. Result: TMS evoked MEPs in o. oculi on both ipsi- and contralateral sides in all subjects. In the paired-pulse study, MEP amplitude in the mentalis decreased at short ISIs of 1–3 ms, followed by increases at 12–20 ms. These effects were similar to those in the FDI. O. oculi did not show a distinct inhibitory period at short ISIs and facilitation at long ISIs was detected but was significantly less than in FDI and mentalis. In o. oculi, there was no significant difference between the effects of ipsilateral and contralateral CS on the MEPs. Conclusion: The bi-hemispheric control of volitional movement and the modulation from brainstem projections appear to markedly influence intracortical inhibitory and excitatory systems in the motor cortical representation of o. oculi.

Evolution of the zygomaticomaxillary region in the genus Homo and its relevance to the origin of modern humans

Metrical and non-metrical analyses of the midfacial region of the genus Homo as viewed in norma frontalis reveal distinct geographical differences in cheek morphology which do not support a replacement model for the origin of modern humans. With the recovery of new Asian fossil hominids it is now clear that fossil Asian faces contrast markedly with many European and African contemporaries. Fossil Asians exhibit much smaller upper and lower midfaces with more horizontally oriented zygomatic bones, pronounced and more medially situated malar tubercles, a distinct incisura malaris, a more acute and inferiorly situated zygomaticomaxillary angle and a vertically shorter maxilla. In comparison with African and Eurasian populations, all these features are also found in higher frequencies in extant Mongoloid populations. European fossil hominids exhibit larger upper and lower facial areas, obliquely oriented zygomatic bones, vertically taller maxillae and zygomatic bones which lack a malar tubercle and incisura malaris. Both Europeans and Mongoloids diverge from the conditions seen in specimens of early Homo in Africa. Morphological traits previously restricted only to fossil Asians now occur in all populations of modern humans. However, their frequency remains higher in populations deriving from or occupying the Far East. The world-wide dissemination of morphological traits which first appeared in the Asian fossil record, suggest that at least some of the facial traits associated with the emergence of modern humans, resulted not from a single African origin, but from admixture and gene flow between different regions of the Old World.