Int. J. Oral Maxillofac. Surg. 2015; 44: 1581–1584 available online at http://www.sciencedirect.com
Letters to the Editor Condylar reconstruction in the treatment of temporomandibular joint ankylosis: a contribution to the ongoing debate and a plea to join forces for tissue engineering strategies Dear Editor, The treatment of temporomandibular joint (TMJ) ankylosis is a challenging problem. An excellent review paper that highlights recent developments, with a specific focus on graft materials for condylar reconstruction, has been published by Khadka and Hu.1 To date, no single method has produced uniformly successful results. Reconstruction with autologous bone grafts, to allow adaptive growth and remodelling, represents the standard treatment in juveniles, while total alloplastic replacement is commonly used in adults, with neither being ideal and both sometimes leading to unwanted adverse effects.2 Over the last 25 years, multiple studies have investigated TMJ characteristics, and while this characterization is not complete, these data have created a solid foundation for tissue-engineering research.3 Recent advances may provide a credible surgical alternative to traditional strategies, with the prospect of using suitably engineered resorbable scaffolds, appropriate biochemical signals, and cell transplantation under investigation worldwide.3 The latest composite materials offer the opportunity to combine biodegradable matrices and osteogenic inorganic phases, such as hydroxyapatite, thus creating nanostructured scaffolds with tailored bioactivity and improved physical and mechanical properties (Fig. 1).4 This trend is explained by the fact that an off-the-shelf product, thus immediately available, would be an ideal graft both from 0901-5027/01201581 + 04
a surgical and commercial standpoint. The application of a cell-free implant that can be reshaped intraoperatively, with the advantages of a one-step simplified procedure plus reduced costs, as well as being ‘smart’ enough to provide the joint with the appropriate stimuli to induce orderly and durable tissue regeneration, has attracted great attention in the orthopaedic community. Kon et al. highlighted the safety and potential of this approach using a knee joint model: patients were evaluated repeatedly through magnetic resonance imaging (MRI) analysis over 5 years of follow-up and showed stable clinical outcomes for both tibiofemoral and patellofemoral
lesions, regardless of age, lesion size, and previous/combined surgery.5 The cell-mediated remodelling induced by the scaffold properties, along with its progressive reabsorption, favoured complete repair of the osteochondral unit. Mehrotra et al. furthered this rationale using a hydroxyapatite/collagen scaffold (60:40 ratio) that was carved to the shape of the condyle after gap arthroplasty in young patients (age 4–16 years) with TMJ ankylosis (Fig. 2).6 Safety and manageability, as much as surgical procedure reproducibility and clinical outcome, were evaluated during up to 18 months of follow-up in order to test the intrinsic regenerative potential
Fig. 1. Hierarchically structured scaffold mimicking the osteochondral architecture with its inherent biological and functional requirements, as well as guiding the growth of each native articular tissue.5
# 2015 Published by Elsevier Ltd on behalf of International Association of Oral and Maxillofacial Surgeons.
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Letters to the Editor Funding
This review was not financially funded. Competing interests
The author has nothing to disclose. The author reports no conflicts of interest related to this study. The author alone is responsible for the content and writing of the paper. Ethical approval
scaffold architecture on cranial bone healing. Int J Oral Maxillofac Surg 2014;43: 506–13. 5. Kon E, Filardo G, Di Martino A, Busacca M, Moio A, Perdisa F, et al. Clinical results and MRI evolution of a nano-composite multilayered biomaterial for osteochondral regeneration at 5 years. Am J Sports Med 2014;42: 158–65. 6. Mehrotra D, Kumar S, Dhasmana S. Hydroxyapatite/collagen block with platelet rich plasma in temporomandibular joint ankylosis: a pilot study in children and adolescents. Br J Oral Maxillofac Surg 2012;50:774–8.
Not required. http://dx.doi.org/10.1016/j.ijom.2015.05.005
Patient consent
Not required. A.C. Profeta1,2,* Otto Schott Institute of Materials Research, Department of Oral and Maxillofacial Surgery/Plastic Surgery, Friedrich-Schiller-University Jena, Jena, Germany 1
Fig. 2. Condylar scaffold fixed to the ramus with a single L-shaped, four-hole, titanium miniplate and screws; a temporal fascia graft was interposed to allow for free movement of the condyle against the glenoid fossa.6
without any cell culture aid. All patients showed appreciable improvements in all range of mandibular movements during the postoperative phase. An anterior open bite, which usually results from bilateral gap arthroplasty, was not seen in any of the cases, as both joints were functional with the vertical height of the ramus restored. Radiographic evaluation at various times showed significant increases in radioopacity, both at the condylar stump and at the interface, confirming neocondylar formation. Noteworthy conclusions can be drawn from these initial results. Customizable gradient-based scaffolds have been reported as a viable option for TMJ reconstruction, allowing closer reproduction of the normal anatomy, a reduced operating time, no donor site morbidity, improved subjective and objective outcomes, and fewer complications. As with the findings from any single clinical trial, these results require verification in other settings, possibly involving an even less invasive fixation technique via bio-adhesives, before the interventions can be recommended for wider implementation. Clinical trials on a larger number of patients, with more researchers and surgeons joining the effort, are needed to strengthen the evidence base for the routine use of these scaffolds and further their development within the specialty.
2
Guy’s and St Thomas’s Hospital NHS Foundation Trust, Department of Oral and Maxillofacial Surgery, Guy’s Hospital, London, UK
*Address: Andrea Corrado Profeta, Otto Schott Institute of Materials Research, Department of Oral and Maxillofacial Surgery/Plastic Surgery, Friedrich-Schiller-University Jena, Fraunhoferstr. 6, D-07743 Jena, Germany. Tel.: +44 7832988574. E-mail addresses: andrea.profeta@kcl. ac.uk, andrea.profeta@uni-jena.de (A.C. Profeta) Available online 21 August 2015 References 1. Khadka A, Hu J. Autogenous grafts for condylar reconstruction in treatment of TMJ ankylosis: current concepts and considerations for the future. Int J Oral Maxillofac Surg 2012;41:94–102. 2. Al-Moraissi EA, El-Sharkawy TM, Mounair RM, El-Ghareeb TI. A systematic review and meta-analysis of the clinical outcomes for various surgical modalities in the management of temporomandibular joint ankylosis. Int J Oral Maxillofac Surg 2015;44: 470–82. 3. Murphy MK, MacBarb RF, Wong ME, Athanasiou KA. Temporomandibular disorders: a review of etiology, clinical management, and tissue engineering strategies. Int J Oral Maxillofac Implants 2013;28:e393–414. 4. Berner A, Woodruff MA, Lam CX, Arafat MT, Saifzadeh S, Steck R, et al. Effects of
A discussion concerning direct bone regeneration on and around inserted dental implants in maxillary sinus lifting procedures without any placement of bony substitutes Dear Editor, We read the article by Bassi et al.1 entitled ‘‘Maxillary sinus lift without grafting, and simultaneous implant placement: a prospective clinical study with a 51-month follow-up’’ with great interest. The authors presented a highly important clinical study of maxillary sinus lift procedures in the posterior region of the maxilla, using no graft material. The sinus mucosa was lifted together with the anterior wall of the osteotomized maxilla, and supported by dental implants. Most importantly, the blood clot was the only filling material around the inserted implants and, as such, the authors claimed a high success rate of bone regeneration. The degree of synthesis and deposition of extracellular collagen matrix followed by bone mineralization was also observed to increase over time and was ascribed to the recruitment and migration of osteogenic cells and their differentiation into osteoblasts. Based on previous studies, Bassi et al.1 postulate that the cells that migrated to the blood clot filling the elevated sinus membrane originated from the bone marrow of the alveolar bone, as well as from the periosteum of the elevated membrane.2 Although we consider the data provided in the reported article to be of great importance, the claimed source of the cells seems somewhat speculative. Therefore, we would like to further support the study concerned with our own data. With regard to the bone-regenerating cells, we have demonstrated that these cells originate