Reliability and validity of handheld structured light scanners and a static stereophotogrammetry system in facial three-dimensional surface imaging

Several new systems for three-dimensional (3D) surface imaging of the face have become available to assess changes following orthognathic or facial surgery. Before they can be implemented in practice, their reliability and validity must be established. Our aim, therefore, was to study the intra- and inter-system reliability and validity of 3dMD (stereophotogrammetry), Artec Eva and Artec Space Spider (both structured light scanners). Intra- and inter-system reliability, expressed in root mean square distance, was determined by scanning a mannequin's head and the faces of healthy volunteers multiple times. Validity was determined by comparing the linear measurements of the scans with the known distances of a 3D printed model. Post-processing errors were also calculated. Intra-system reliability after scanning the mannequin's head was best with the Artec Space Spider (0.04 mm Spider; 0.07 mm 3dMD; 0.08 mm Eva). The least difference in inter-system reliability after scanning the mannequin's head was between the Artec Space Spider and Artec Eva. The best intra-system reliability after scanning human subjects was with the Artec Space Spider (0.15 mm Spider; 0.20 mm Eva; 0.23 mm 3dMD). The least difference in inter-system reliability after scanning human subjects was between the Artec Eva and Artec Space Spider. The most accurate linear measurement validity occurred with the Artec Space Spider. The post-processing error was 0.01 mm for all the systems. The Artec Space Spider is the most reliable and valid scanning system.

[Adjunctive aesthetic procedures in orthognathic surgery]

In addition to function, occlusion and airway volume, aesthetics play an important role in the planning and execution of orthognathic surgery. To improve the aesthetic outcome of orthognathic surgery, there are several procedures that can be combined with orthognathic surgery secondarily, or in the same operation. These include: lipofilling, dermal fillers, facial implants, liposuction, ear corrections, eyelid corrections, or a lip lift. Patients often appreciate it when the options for additional procedures are discussed. However, both undertreatment and overtreatment can lead to unfavorable outcomes. Proper care and thoroughness are of course required, as to not change the characteristic facial aspects of a patient too much.

Mechanical Fractionation of Adipose Tissue-A Scoping Review of Procedures to Obtain Stromal Vascular Fraction

Clinical indications for adipose tissue therapy are expanding towards a regenerative-based approach. Adipose-derived stromal vascular fraction consists of extracellular matrix and all nonadipocyte cells such as connective tissue cells including fibroblasts, adipose-derived stromal cells (ASCs) and vascular cells. Tissue stromal vascular fraction (tSVF) is obtained by mechanical fractionation, forcing adipose tissue through a device with one or more small hole(s) or cutting blades between syringes. The aim of this scoping review was to assess the efficacy of mechanical fractionation procedures to obtain tSVF. In addition, we provide an overview of the clinical, that is, therapeutic, efficacy of tSVF isolated by mechanical fraction on skin rejuvenation, wound healing and osteoarthritis. Procedures to obtain tissue stromal vascular fraction using mechanical fractionation and their associated validation data were included for comparison. For clinical outcome comparison, both animal and human studies that reported results after tSVF injection were included. We categorized mechanical fractionation procedures into filtration (n = 4), centrifugation (n = 8), both filtration and centrifugation (n = 3) and other methods (n = 3). In total, 1465 patients and 410 animals were described in the included clinical studies. tSVF seems to have a more positive clinical outcome in diseases with a high proinflammatory character such as osteoarthritis or (disturbed) wound healing, in comparison with skin rejuvenation of aging skin. Isolation of tSVF is obtained by disruption of adipocytes and therefore volume is reduced. Procedures consisting of centrifugation prior to mechanical fractionation seem to be most effective in volume reduction and thus isolation of tSVF. tSVF injection seems to be especially beneficial in clinical applications such as osteoarthritis or wound healing. Clinical application of tSVF appeared to be independent of the preparation procedure, which indicates that current methods are highly versatile.

Morphological Variation of the Mandible in the Orthognathic Population-A Morphological Study Using Statistical Shape Modelling

The aim of this study was to investigate the value of 3D Statistical Shape Modelling for orthognathic surgery planning. The goal was to objectify shape variations in the orthognathic population and differences between male and female patients by means of a statistical shape modelling method. Pre-operative CBCT scans of patients for whom 3D Virtual Surgical Plans (3D VSP) were developed at the University Medical Center Groningen between 2019 and 2020 were included. Automatic segmentation algorithms were used to create 3D models of the mandibles, and the statistical shape model was built through principal component analysis. Unpaired t-tests were performed to compare the principal components of the male and female models. A total of 194 patients (130 females and 64 males) were included. The mandibular shape could be visually described by the first five principal components: (1) The height of the mandibular ramus and condyles, (2) the variation in the gonial angle of the mandible, (3) the width of the ramus and the anterior/posterior projection of the chin, (4) the lateral projection of the mandible's angle, and (5) the lateral slope of the ramus and the inter-condylar distance. The statistical test showed significant differences between male and female mandibular shapes in 10 principal components. This study demonstrates the feasibility of using statistical shape modelling to inform physicians about mandible shape variations and relevant differences between male and female mandibles. The information obtained from this study could be used to quantify masculine and feminine mandibular shape aspects and to improve surgical planning for mandibular shape manipulations.

Effects of Upper Blepharoplasty Techniques on Headaches, Eyebrow Position, and Electromyographic Outcomes: A Randomized Controlled Trial

The aim of this study was to assess changes in headaches, eyebrow height, and electromyographic (EMG) outcomes of the frontalis and orbicularis oculi muscles, after an upper blepharoplasty with or without resecting a strip of orbicularis oculi muscle. In a randomized controlled trial, 54 patients received an upper blepharoplasty involving either only removing skin (group A) or removing skin with an additional strip of orbicularis muscle (group B). Preoperative, and 6 and 12 months postoperative headache complaints were assessed using the HIT-6 scores and eyebrow heights were measured on standardised photographs. Surface EMG measurements, i.e., electrical activity and muscle fatigue, were assessed for the frontalis and orbicularis oculi muscles preoperatively and 2, 6, and 12 months postoperatively. Significantly fewer headaches were reported following a blepharoplasty. The eyebrow height had decreased, but did not differ between groups. Regarding the surface EMG measurements, only group A's frontalis muscle electrical activity had decreased significantly during maximal contraction 12 months after surgery (80 vs. 39 mV, p = 0.026). Fatigue of both the frontalis and the orbicularis oculi muscles did not change significantly postoperatively compared to baseline. EMG differences between groups were minor and clinically insignificant. The eyebrow height decreased and patients reported less headaches after upper blepharoplasty irrespective of the used technique.

A Systematic Review of the Efficacy of Microfocused Ultrasound for Facial Skin Tightening

Objective: to systematically review the efficacy of microfocused ultrasound (MFU) for facial skin tightening. Methods: A systematic search was performed (Pubmed, Embase) to assess the efficacy of single MFU treatments for facial skin tightening. Eligible studies included randomised controlled trials, controlled trials, cohort studies and case series (n ≥ 10). Objective and subjective outcomes were assessed. Results: A total of 693 studies were identified of which 16 studies were eligible. All the studies involved female patients. MFU is capable of tightening the skin, as observed in studies measuring the results of brow lifts (0.47−1.7 mm) and submental lifts (measured as a 26−45 mm2 reduction in the submental area on lateral photographs). Data from the Global Aesthetic Improvement Scale (GAIS) were pooled, and the day 90 pooled subjective investigator reported scores (IGAIS) (n = 337) showed that 92% of the patients demonstrated an improvement in skin tightening and/or in wrinkle reduction which continued up to one year. Longer-term follow-up data are not available. The patient-reported pooled scores (SGAIS) (n = 81) showed that the skin improvements were mild and continued to increase from 42% (90 days) to 53% (360 days) post-treatment. The MFU treatment was moderately painful and caused transient erythema with or without oedema. Other adverse effects were rare (2%), including dysesthesia (numbness or hypersensitivity), bruising and stinging, mandibular burns, striations and contact dermatitis. Various device settings, treatment protocols and energies were applied. Excessive skin laxity and a BMI > 30 were posed as relative contraindications for MFU treatment because positive results declined with an increase in laxity and BMI. Conclusions: MFU treatment is effective in tightening female patients’ mildly to moderately lax facial skin. Future studies should focus on objective treatment outcomes, optimising treatment regimens and male patients.

Supplementation of Facial Fat Grafting to Increase Volume Retention: A Systematic Review

BACKGROUND

For decades, facial fat grafting has been used in clinical practice for volume restoration. The main challenge of this technique is variable volume retention. The addition of supplements to augment fat grafts and increase volume retention has been reported in recent years.

OBJECTIVES

The aim of this systematic review was to investigate which supplements increase volume retention in facial fat grafting as assessed by volumetric outcomes and patient satisfaction.

METHODS

Embase, Medline, Ovid, Web of Science Core Collection, Cochrane Central Register of Controlled Trials, and Google Scholar were searched up to November 30, 2020. Only studies assessing volume after facial fat grafting with supplementation in human subjects were included. Outcomes of interest were volume or patient satisfaction. The quality of the studies was assessed with the Effective Public Health Practice Project tool.

RESULTS

After duplicates were removed 3724 studies were screened by title and abstract. After reading 95 full-text articles, 27 studies were eligible and included for comparison. Supplementation comprised of platelet-rich plasma, platelet-rich fibrin, adipose tissue-derived stromal cells or bone marrow-derived stromal cells, cellular or tissue stromal vascular fraction, or nanofat. In 13 out of 22 studies the supplemented group showed improved volumetric retention and 5 out of 16 studies showed greater satisfaction. The scientific quality of the studies was rated as weak for 20 of 27 studies, moderate for 6 of 27 studies, and strong for 1 study.

CONCLUSIONS

It remains unclear if additives contribute to facial fat graft retention and there is a need to standardize methodology.

LEVEL OF EVIDENCE: 4

Postoperative skeletal stability at the one-year follow-up after splintless Le Fort I osteotomy using patient-specific osteosynthesis versus conventional osteosynthesis: a randomized controlled trial

The purpose of this study was to assess the 1-year skeletal stability of the osteotomized maxilla after Le Fort I surgery, comparing conventional osteosynthesis with patient-specific osteosynthesis. Patients were assigned to a conventional or patient-specific osteosynthesis group using prospective randomization. The primary outcome was the three-dimensional change in postoperative skeletal position of the maxilla between the 2-week and 1-year follow-up cone beam computed tomography scans. Fifty-eight patients completed the protocol for the 2-week postoperative analysis, and 27 patients completed the 1-year follow-up study protocol. Of the 27 patients completing the entire protocol, 13 were in the conventional group and 14 in the patient-specific osteosynthesis group. The three-dimensional translation analysis showed that the use of the patient-specific osteosynthesis resulted in a skeletally stable result, comparable to that of conventional miniplate fixation. For both the patient-specific osteosynthesis and conventional miniplate fixation groups, median translations of less than 1 mm and median rotations of less than 1° were observed, indicating that both methods of fixation resulted in a stable result for the 27 patients examined. For the Le Fort I osteotomy, the choice between patient-specific osteosynthesis and conventional osteosynthesis did not affect the postoperative skeletal stability after 1 year of follow-up.

Impact of upper blepharoplasty, with or without orbicularis oculi muscle removal, on tear film dynamics and dry eye symptoms: A randomized controlled trial

PURPOSE

Upper blepharoplasty may be related to dry eye symptoms since the function of the orbicularis oculi muscle may affect the tear film. We aimed to assess the effect of blepharoplasty with or without the removal of a strip of orbicularis oculi muscle on tear film dynamics and dry eye symptoms.

METHODS

A double-blind, randomized, controlled trial comparing upper blepharoplasty without (group A) or with (group B) orbicularis oculi muscle excision was performed on 54 healthy Caucasian patients. Tear film dynamics and dry eye symptoms were evaluated using multiple dry eye parameters, i.e. tear osmolarity, Schirmer test I, corneal/conjunctival staining, tear break-up time (TBUT), Oxford Scheme, Sicca Ocular Staining Score and Ocular Surface Disease Index questionnaire. All the parameters were assessed preoperatively and 6 and 12 months after upper blepharoplasty. All the groups' outcomes were compared.

RESULTS

The differences were not significant between the two upper blepharoplasty techniques regarding most of the above-mentioned outcomes. Subjective symptoms of ocular irritation, consistent with dry eye disease and vision-related impairment, were reduced after upper blepharoplasty independent of the type of the technique applied, while the pre and postoperative outcomes of the objective tear dynamics did not differ 12 months after surgery. However, group B demonstrated a significant increase in tear osmolarity and TBUT at the 6-month follow-up visit.

CONCLUSION

An upper blepharoplasty alleviates subjective dry eye complaints in the long term, while not changing the tear dynamics. The improvement was independent of the blepharoplasty technique used.

The use of xenografts to prevent inferior border defects following bilateral sagittal split osteotomies: three-dimensional skeletal analysis using cone beam computed tomography

The aim of this retrospective study was to investigate grafting in the osteotomy gap during bilateral sagittal split osteotomy (BSSO), using a xenograft and fibrin glue. Hard tissue defects in the inferior mandibular border were assessed using cone beam computed tomography scans taken 1 week and 1year postoperatively. The study group of 20 patients underwent bone grafting during BSSO (mean age 26.1years; mean horizontal displacement 8.5mm) and the control group of 20 patients did not (mean age 30.2 years; mean horizontal displacement 7.6mm). The mean height of the mandibular defects was significantly lower in the study group, but there was no significant difference in volume measurements between the groups. Grafting had a negligible effect on large displacements (9.0-15.0mm), which might have been due to an inadequate amount and/or positioning of the graft, or to poor dimensional stability. This may be resolved by improved graft positioning or by using a different kind of (xeno)graft.

Aesthetic outcomes of upper eyelid blepharoplasty: a systematic review

Although upper blepharoplasty is a common cosmetic surgical intervention, a better scientific understanding of the aesthetic results and the preferred surgical technique to achieve the best aesthetic results is still needed. A systematic search using four search engines (PubMed, Embase, CINAHL, and Cochrane) was performed to identify any study on the aesthetic outcome of a solitary upper blepharoplasty; these were subjected to quality assessment for possible inclusion. Eligible studies were randomized controlled trials, controlled trials, cohort studies, and case series (n ≥ 10). A total of 4043 studies were assessed, of which 26 were included. Aesthetic outcomes included patient-reported outcome measures, scarring, eyebrow height, tarsal platform show, and panel or expert evaluation. Meta-analysis was not possible. Patients were generally satisfied with the aesthetic result and scar formation after an upper blepharoplasty. The amount of tarsal platform show increases, which positively affects the aesthetics. The eyebrow seems to move down slightly. The surgical technique used (skin only or skin/muscle removal) did not influence patient satisfaction or the physician-assessed aesthetic outcomes. Patients are generally satisfied after an upper blepharoplasty. The optimal design of the skin excision is still a matter of debate, especially when addressing lateral hooding. Further objective research is advised.

Functional outcomes of upper eyelid blepharoplasty: A systematic review

OBJECTIVE

Various functional outcomes after upper blepharoplasty are reported in the literature. We systematically reviewed the literature to assess the objective and subjective functional effects of upper blepharoplasty.

METHODS

After a systematic search of four search engines (Pubmed, Embase, Cinahl and Cochraine), any study on objective and subjective (patient reported) functional outcome after upper blepharoplasty was subjected to a quality assessment for possible inclusion in the review. The intervention was defined as a solitary surgical upper blepharoplasty containing the removal of skin, with or without the removal of a strip of orbicularis oculi muscle and/or upper orbital fat. Eligible studies were randomized controlled trials, controlled trials, cohort studies and case series (n ≥ 10).

RESULTS

A total of 3525 studies were assessed, of which 28 studies were included in this systematic review. Favorable outcomes after an upper blepharoplasty were reported and included enlarged visual field, enhanced quality of life related to fewer headaches and improved vision. Furthermore, sensitivity of the eyelids decreased, with differences in recovery. Outcomes for eyebrow height, astigmatism, contrast sensitivity and eyelid kinematics were not consistent between the studies. No meta-analysis could be performed due to the limited scope of included studies and the great variety in outcomes and blepharoplasty techniques.

CONCLUSIONS

Upper blepharoplasty is accompanied by a great variety of beneficial functional outcomes including an increased visual field and improvement in headache- and vision-related quality of life. Further research is needed, especially where results are conflicting (effects on eye dryness and eyebrow height) and/or the data are limited (contrast sensitivity, astigmatism).

Optimisation of three-dimensional lower jaw resection margin planning using a novel Black Bone magnetic resonance imaging protocol

BACKGROUND

MRI is the optimal method for sensitive detection of tumour tissue and pre-operative staging in oral cancer. When jawbone resections are necessary, the current standard of care for oral tumour surgery in our hospital is 3D virtual planning from CT data. 3D printed jawbone cutting guides are designed from the CT data. The tumour margins are difficult to visualise on CT, whereas they are clearly visible on MRI scans. The aim of this study was to change the conventional CT-based workflow by developing a method for 3D MRI-based lower jaw models. The MRI-based visualisation of the tumour aids in planning bone resection margins.

MATERIALS AND FINDINGS

A workflow for MRI-based 3D surgical planning with bone cutting guides was developed using a four-step approach. Key MRI parameters were defined (phase 1), followed by an application of selected Black Bone MRI sequences on healthy volunteers (phase 2). Three Black Bone MRI sequences were chosen for phase 3: standard, fat saturated, and an out of phase sequence. These protocols were validated by applying them on patients (n = 10) and comparison to corresponding CT data. The mean deviation values between the MRI- and the CT-based models were 0.63, 0.59 and 0.80 mm for the three evaluated Black Bone MRI sequences. Phase 4 entailed examination of the clinical value during surgery, using excellently fitting printed bone cutting guides designed from MRI-based lower jaw models, in two patients with oral cancer. The mean deviation of the resection planes was 2.3 mm, 3.8 mm for the fibula segments, and the mean axis deviation was the fibula segments of 1.9°.

CONCLUSIONS

This study offers a method for 3D virtual resection planning and surgery using cutting guides based solely on MRI imaging. Therefore, no additional CT data are required for 3D virtual planning in oral cancer surgery.

Multi-modality 3D mandibular resection planning in head and neck cancer using CT and MRI data fusion: A clinical series

OBJECTIVES

3D virtual surgical planning (VSP) and guided surgery has been proven to be an effective tool for resection and reconstruction of the mandible. Currently, most widely used 3D VSP approaches to mandibular resection do not include detailed tumour information in the VSP. This manuscript presents a strategy where the aim was to incorporate tumour visualisation into the 3D virtual plan. Three-dimensional VSP of the mandibular resections was based on the fusion of CT and MRI data which was subsequently applied in clinical practice.

METHODS

All patients diagnosed with oral squamous cell carcinoma between 2014 and 2017 at the University Medical Centre Groningen were included. The tumour was delineated on the MRI data, after which this dataset was fused with the CT bone data in order to construct a 3D bone and tumour model for virtual resection planning. Guided resections were performed and post-operative evaluation quantified the accuracy of the resection. The histopathological findings and patient and tumour characteristics were compared to those of a historical cohort (2009-2014) of conventional mandibular continuity resections.

RESULTS

Twenty-four patients were included in the cohort. The average deviation from planned resection was found to be 2.2 mm. Histopathologic analysis confirmed all resection planes (bone) were tumour free, compared to 96.4% in the historic cohort.

CONCLUSION

MRI-CT base tumour visualisation and 3D resection planning is a safe and accurate method for oncologic resection of the mandible. It is an improvement on the current methods reported for 3D resection planning based solely on CT data.

The design, production and clinical application of 3D patient-specific implants with drilling guides for acetabular surgery

An innovative procedure for the development of 3D patient-specific implants with drilling guides for acetabular fracture surgery is presented. By using CT data and 3D surgical planning software, a virtual model of the fractured pelvis was created. During this process the fracture was virtually reduced. Based on the reduced fracture model, patient-specific titanium plates including polyamide drilling guides were designed, 3D printed and milled for intra-operative use. One of the advantages of this procedure is that the personalised plates could be tailored to both the shape of the pelvis and the type of fracture. The optimal screw directions and sizes were predetermined in the 3D model. The virtual plan was translated towards the surgical procedure by using the surgical guides and patient-specific osteosynthesis. Besides the description of the newly developed multi-disciplinary workflow, a clinical case example is presented to demonstrate that this technique is feasible and promising for the operative treatment of complex acetabular fractures.

[The 3D-printed dental splint: a valuable tool in the surgical treatment of malocclusion after polytrauma]

A 22-year old male was referred to the Department of Oral and Maxillofacial Surgery of a university clinic 2 months after he had sustained multiple traumatic injuries abroad because of an anterior malocclusion. The malocclusion was the sequel of an unrecognised, untreated, already consolidated paramedian mandibular fracture on the right and a fracture of the contralateral mandibular angle on the left. Preoperatively, a cobalt-chrome 3D-printed dental splint was prepared. Surgical correction of the malocclusion was carried out by segmental osteotomies of the mandible at the original fracture sites. This involved a vertical paramedian osteotomy on the right side and a unilateral sagittal split osteotomy on the left mandibular angle side. The mandibular segment was mobilised in the correct occlusion with the aid of the 3D-printed dental splint. The splint was fixed to the teeth with dental composite. The custom made 3D-printed dental splint is considered a promising procedural innovation in oral and maxillofacial surgery.

Accuracy of fibula reconstruction using patient-specific CAD/CAM reconstruction plates and dental implants: A new modality for functional reconstruction of mandibular defects

BACKGROUND

The purpose of this study was to analyze the accuracy of mandibular reconstruction using patient-specific computer-aided designed and computer-aided manufactured (CAD/CAM) reconstruction plates as a guide to place fibula grafts and dental implants in a one-stage procedure using pre-operative 3D virtual planning.

METHODS

Seven consecutive patients were analyzed retrospectively, the 3D accuracy of placement of the fibula grafts and dental implants was compared to the virtual plan.

RESULTS

Six out of seven flaps survived for an average follow-up time of 9.4 months. The outcome was compared to the virtual plan, superimposed on the mandible. For the fibula segments, the mean deviation (SD) was 3.0 (1.8) mm and the mean angulation (SD) was 4.2° (3.2°). For the implants, the mean deviation (SD) was 3.3 (1.3) mm and the mean angulation (SD) was 13.0° (6.7°). The mean (SD) mandibular resection plane deviation was 1.8 (0.9) mm.

CONCLUSIONS

A patient-specific reconstruction plate is a valuable tool in the reconstruction of mandibular defects with fibula grafts and dental implants. Implant angulation showed a greater deviation from the virtual plans in patients with a sharp ventral fibula rim, where the guide is removed after pilot drilling of the implants.

Calculating nasoseptal flap dimensions: a cadaveric study using cone beam computed tomography

We hypothesize that three-dimensional imaging using cone beam computed tomography (CBCT) is suitable for calculating nasoseptal flap (NSF) dimensions. To evaluate our hypothesis, we compared CBCT NSF dimensions with anatomical dissections. The NSF reach and vascularity were studied. In an anatomical study (n = 10), CBCT NSF length and surface were calculated and compared with anatomical dissections. The NSF position was evaluated by placing the NSF from the anterior sphenoid sinus wall and from the sella along the skull base towards the frontal sinus. To visualize the NSF vascularity in CBCT, the external carotic arteries were perfused with colored Iomeron. Correlations between CBCT NSFs and anatomical dissections were strongly positive (r > 0.70). The CBCT NSF surface was 19.8 cm(2) [16.6-22.3] and the left and right CBCT NSF lengths were 78.3 mm [73.2-89.5] and 77.7 mm [72.2-88.4] respectively. Covering of the anterior skull base was possible by positioning the NSF anterior to the sphenoid sinus. If the NSF was positioned from the sella along the skull base towards the frontal sinus, the NSF reached partially into the anterior ethmoidal sinuses. CBCT is a valuable technique for calculating NSF dimensions. CBCT to demonstrate septum vascularity in cadavers proved to be less suitable. The NSF reach for covering the anterior skull base depends on positioning. This study encourages preoperative planning of a customized NSF, in an attempt to spare septal mucosa. In the concept of minimal invasive surgery, accompanied by providing customized care, this can benefit the patients' postoperative complaints.

[Blepharoplasty in aesthetic facial surgery]

Blepharoplasty is the most commonly performed procedure in aesthetic facial surgery. The upper eyelid is part of the same aesthetic subunit as the eyebrow and the lower eyelid is part of the same aesthetic subunit as the cheek. In upper eyelid blepharoplasty the excess skin and possibly also a portion of the sphincter is removed. A low-hanging eyebrow is preferably corrected by lifting the brow instead of over excising the redundant eyelid skin. Blepharoplasty of the lower eyelid is generally carried out by a very limited excision of the skin and the orbicularis oculi muscle in order to prevent lower lid retraction (ectropion). Rejuvenation in the lower lid region is also achieved by fat resection or redistribution, by means of which the double convex contour deformity is reduced. Blepharoplasty is generally performed under local anaesthesia and complications are rare. Patient satisfaction is generally high.

[Microfat transfer in cosmetic facial procedures]

Loss of volume in the soft tissues of the face is considered to be an important cause of facial ageing. This volume loss can be compensated by microfattransfer. This technique offers a natural and long-lasting effect. Fat is harvested with liposuction and after centrifugation it is injected into the target areas in the face using small blunt cannulas. The goal is to place the fat in the desired place in such a way that the fat will survive and become integrated in the acceptor tissue. Microfattransfer can be combined with other cosmetic facial procedures such as blepharoplasties and facelifts. Although fatgrafting is a safe technique, complications may occur. These are mostly related to technique and amount of fat injected. Microfattransfer is a useful adjunctive procedure in maxillofacial surgery. Because only 40-50% of the result of microfattransfer is permanent touching up is often necessary. Microfattransfer should be considered as a staged treatment modality.

[Wrinkle fillers in cosmetic facial procedures]

During the last decade cosmeticfacial procedures have become part of the professional work of both dentists and maxillofacial surgeons. A shift has taken place from invasive surgical treatment towards minimally invasive treatments. Besides the use ofbotulinum toxin type A, non-permanent wrinkle fillers can be an alternative to invasive surgical treatment. Since botulism was first described in the 18th century, the neurotoxin has continued to develop, as a result of which Botox, now available in synthetically produced form, can safely be employed in healthcare. The frequency with which patients visit dentists and maxillofacial surgeons offers the professional group the possibility to inform patients about cosmetic facial treatments and to carry them out according to diagnosis.

Maxillomandibular advancement surgery as alternative to continuous positive airway pressure in morbidly severe obstructive sleep apnea: a case report

Obstructive sleep apnea syndrome (OSAS) is a sleep-related breathing disorder, characterized by disrupted snoring and repetitive upper airway obstructions. Oral appliance therapy is an effective alternative to continuous positive airway pressure (CPAP) and is especially effective in mild and moderate OSAS cases. Successful oral appliance therapy has been suggested as a predictor for successful maxillomandibular advancement (MMA) surgery in OSAS patients. MMA surgery has gained increasing popularity in this field since this procedure is associated with an enlargement of the entire velo-oro-hypopharyngeal airway. The authors present an unusual case of a CPAP-intolerant morbidly obese female (body mass index (BMI) = 40) with morbidly severe OSAS (apnea-hypopnea index (AHI) = 139, lowest oxyhemoglobin saturation level = 73%), who underwent a successful combination of MMA surgery, a modified genioplasty and cervicomental liposuction after oral appliance therapy. The post-surgical AHI was 6, and the lowest oxyhemoglobin saturation level increased to 86%. The authors suggest that this surgical combination should be seriously considered in obese patients with severe OSAS and CPAP intolerance.

[Three dimensional technology and reconstructions of large defects of the jaw]

3D technology is increasingly being applied in dentistry and in oral and maxillofacial surgery. An important field of application is reconstructive surgery, especially in the reconstruction of large defects ofthe jaw. In such cases of reconstruction, the goal is the restoration of both the continuity of the defective area and its function. For the functional restoration implant supported dental structures are often employed. In such cases, CAD/CAM superstructures, 3D printed drill and saw templates, anatomical models, wafers and surgical outcome models are used. The combination of the digital planning and the digital fabrication ofsuperstructures and surgical aids offers many preoperative advantages. The use of saw, drill and positioning templates provides for accurate segmentation and implant positioning, by means of which the reconstruction can be carried out in a predictable way.

Segmentation process significantly influences the accuracy of 3D surface models derived from cone beam computed tomography

AIMS

To assess the accuracy of surface models derived from 3D cone beam computed tomography (CBCT) with two different segmentation protocols.

MATERIALS AND METHODS

Seven fresh-frozen cadaver heads were used. There was no conflict of interests in this study. CBCT scans were made of the heads and 3D surface models were created of the mandible using two different segmentation protocols. The one series of 3D models was segmented by a commercial software company, while the other series was done by an experienced 3D clinician. The heads were then macerated following a standard process. A high resolution laser surface scanner was used to make a 3D model of the macerated mandibles, which acted as the reference 3D model or "gold standard". The 3D models generated from the two rendering protocols were compared with the "gold standard" using a point-based rigid registration algorithm to superimpose the three 3D models. The linear difference at 25 anatomic and cephalometric landmarks between the laser surface scan and the 3D models generate from the two rendering protocols was measured repeatedly in two sessions with one week interval.

RESULTS

The agreement between the repeated measurement was excellent (ICC=0.923-1.000). The mean deviation from the gold standard by the 3D models generated from the CS group was 0.330mm±0.427, while the mean deviation from the Clinician's rendering was 0.763mm±0.392. The surface models segmented by both CS and DS protocols tend to be larger than those of the reference models. In the DS group, the biggest mean differences with the LSS models were found at the points ConLatR (CI: 0.83-1.23), ConMedR (CI: -3.16 to 2.25), CoLatL (CI: -0.68 to 2.23), Spine (CI: 1.19-2.28), ConAntL (CI: 0.84-1.69), ConSupR (CI: -1.12 to 1.47) and RetMolR (CI: 0.84-1.80).

CONCLUSION

The Commercially segmented models resembled the reality more closely than the Doctor's segmented models. If 3D models are needed for surgical drilling guides or surgical planning which requires high precision, the additional cost of the commercial segmentation services seem to be justified to produce a more accurate surface models.

Assessment of the microbiota of a mixed infection of the tongue using phenotypic and genotypic methods simultaneously and a review of the literature

We assessed the microbiota of a tongue abscess in which twelve different aerobic and anaerobic bacteria were identified using fluorescent in situ hybridisation (FISH), sequencing of the 16S rRNA gene and phenotypic methods. By applying the 16S rRNA based probes directly on the clinical material, a quick insight of the bacteria present was obtained and the species which were not cultured but present in the abscess were identified.

[Delayed wound healing post molar extraction]

One month post extraction of the second left maxillary molar the alveolar extraction site showed no signs of healing and was painful. The patient had been using an oral bisphosphonate during 3 years. Therefore, the lesion was diagnosed as bisphosphonate-induced maxillary osteonecrosis. Treatment was conservative. Since one month later the pain had increased and the wound healing had decreased, a biopsy was carried out. Histopathologic examination revealed a non-Hodgkin lymphoma.

Effect of postoperative radiotherapy on the functional result of implants placed during ablative surgery for oral cancer

The purpose of this retrospective study was to evaluate the survival of dental implants placed during ablative surgery in the interforaminal region of the original edentulous mandible in patients with squamous cell carcinoma of the oral cavity in relation to postoperative radiotherapy. Forty-eight patients treated in 1996-2003 with surgery alone or in combination with postoperative radiotherapy were analysed. In all patients, 2 to 4 Brånemark Mk II/III 2-phase implants were placed during tumour resection. A total of 139 implants were placed of which 61 (21 patients) received postoperative radiotherapy: 60-68 Gy as a boost dose on the primary tumour site and 10-68 Gy on the symphyseal area. No difference was found in percentage of functional dentures on implants between the radiated and non-radiated groups. The success rate of osseointegration was 97% in the postoperative irradiated group and 100% in the non-irradiated group. The prosthetic success rate (75%) was lower because in 12 of the 48 patients (34 implants) a functional denture could not be fitted due to tumour recurrence or metastasis (7 patients, 22 implants) or for psychological reasons (4 patients, 12 implants), independent of whether radiotherapy was administered. Postoperative radiotherapy does not affect the osseointegration of dental implants placed during tumour ablation and the ultimate number of functional dentures. Primary implant placement in edentulous mandibles may have advantages over secondary implant placement in patients with oral squamous cell carcinoma.