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CLINICAL SCIENCE AND TECHNIQUES

Stereolithography in Oral Implantology A Comparison of Surgical Guides

Sammartino, Gilberto MD, DDS*; Valle, Antonio Della DMD; Marenzi, Gaetano DMD, PhD; Gerbino, Salvatore PhD§; Martorelli, Massimo PhD||; di Lauro, Alessandro Espedito DMD, PhD; di Lauro, Francesco MD, DDS**

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doi: 10.1097/01.ID.0000127526.36938.4C
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Abstract

The stereolithography process is a rapid prototyping method that produces physical models by selectively solidifying an ultraviolet-sensitive liquid resin using a laser beam. 1–5 It represents a relatively new technology in the diagnostic area. The status of this new methodology in clinical and surgical medicine is still at the prototype stage. It can be used for surgical simulation to assure predictable results and to diminish operation time. 1–7 In oral implantology, this technology allows for a precise evaluation of anatomic points such as the size of the maxillary sinus in the upper jaw and the location of the alveolar nerve in the lower jaw, 1–8 and it can be applied to provide information about size, direction, and bone location for accurate positioning of implants. 1–9 This study evaluated the possible benefits in planning implant surgery from stereolithographic models and surgical guides relating to clinical guidance methodology. 1–5

The aim of this report is to consider the use of stereolithography in oral implantology and its role in reducing complications in implant dentistry.

Case Report

A 70-year-old woman with severe mandibular bone atrophy had been presented to our department (Fig. 1). She indicated that her removable complete denture was unstable and caused considerable interference with mastication and speech despite the fact that the restoration had been reworked several times. It was decided to implant 2 fixtures that could assure better stability for a lower prosthesis, so she agreed to implant surgery. To avoid dislocation of the denture, 2 Branemark implants (Nobel Biocare USA, Yorba Linda, CA) 3.75 mm in diameter and 10 mm in length, were used. The implants were located evaluating bone quantity and density by computed tomographic (CT) analysis and its elaboration by SurgiCase software 10–12 (Fig. 2). Preoperative x-ray showed the real bone jaw atrophy that was identified as a V-VI Cawood-Howell Class. To determine the fixation points of the fixtures, a mandibular model and tomographic analysis were used. By means of these examinations, an initial surgical guide was fabricated in which each implant was to be located considering mandibular dimensions and clinical evaluations (gnathologic aspects, relations, and ideal aesthetic teeth positions) (Fig. 3). The fixation points were identified considering bone height, width, and density that could assure adequate primary stability immediately after the fixtures were inserted. Of course, in this preoperative planning, according to CT data, the course of the mandibular canal and its contents of nerve and vessels 4 were also evaluated.

Fig. 1.
Fig. 1.:
Intraoral vision of bone jaw atrophy.
Fig. 2.
Fig. 2.:
Preoperative computed tomography images. The inferior alveolar nerve is represented in the cross-sectional and panoramic reformats. The buccolingual contour and the vertical dimension of available bone are well represented in the cross-sectional images.
Fig. 3.
Fig. 3.:
Traditional method for the construction of a surgical guide. Clinical guide and plastic pins.

At the same time, a second surgical guide was made by stereolithographic technique. SurgiCase software allows for the regeneration of 3-dimensional images of the jaw anatomy, which can simulate the insertion of the fixtures. Even bone density in the area of the future implant location can be taken into account. 4–13 This system contains cylindrical representations of oral implants, and their lengths and diameters can be modified according to the available product sizes of the implant manufacturer so as to obtain the best use of the available bone, and when possible, the contact with the cortical parts of the jaw bone. 4–14

The bone density value allows developing a bone map, where it is possible to identify the sites that could assure the fixtures’ major primary stability and offer better resistance to the biting forces.

The CT data were also used to construct a stereolithographic mandibular model (Fig. 4).

Fig. 4.
Fig. 4.:
The stereolithographic mandibular model in which the individual jaw bone morphology is accurately represented.

The analysis of this new model allowed for the construction of another surgical guide that had drilling cylinders that assured the surgical fixtures fitting in the same mandibular sites and directions as the implants in the planned SurgiCase software simulation (Fig. 5). The guiding cylinders are made of stainless steel, which are positioned to extend 5 mm above the residual ridge. The diameters of the cylinders are 0.2 mm greater than the diameter of the specified drill. As a result of this technology, the surgical guide permits accurate and consistent position and orientation of the implants 4–15 (Fig. 6).

Fig. 5.
Fig. 5.:
The stereolithographic surgical guides. The guiding cylinders are made of stainless steel and their diameters are 0.2 mm greater than the diameter of the specified drill.
Fig. 6.
Fig. 6.:
The surgical guide on the stereolithographic mandibular model. Its stability is achieved by the accuracy of fit.

It was noted that the planned fixation points according to the stereo-lithographic surgical guide were not in the same areas selected by the clinical surgical guide (Figs. 7–10). The distribution of the fixtures identified by the stereolithographic surgical guide created with the mandibular midline a triangular plane, which was bigger than the geometric plane obtained by the distribution of the fixtures selected with the clinical surgical guide (Fig. 11). The stereolithographic analysis identified a mandibular area that could assure better denture stability. Furthermore, the software allows the practitioner to view a longitudinal and a concentric graph of bone density value around each individual implant planned. 4

Fig. 7.
Fig. 7.:
Two-dimensional image of the planned implant positions: clinical sites (green) and stereolithographic sites (yellow).
Fig. 8.
Fig. 8.:
Three-dimensional image of clinical (white) and stereolithographic (green) fixture orientation: frontal view.
Fig. 9.
Fig. 9.:
Three-dimensional image of clinical (white) and stereolithographic (green) fixture orientation: occlusal view.
Fig. 10.
Fig. 10.:
Three-dimensional image of clinical (white) and stereolithographic (green) fixture orientation: lateral view.
Fig. 11.
Fig. 11.:
Three-dimensional image in frontal craniocaudal version shows the distribution of the fixtures identified by the stereolithographic surgical guide, created with the mandibular midline, a triangular plane which was bigger than the geometric plane obtained by the distribution of the fixtures selected with the clinical surgical guide. This area of major extension is able to assure better stability to the denture.

The comparison between stereolithographic and clinical guides indicated different bone densities between stereolithographic and clinical fixation points. The density values were expressed in Hounsfield units. The fixation points selected by the stereolithographic technique showed more density (right site = 502.32 H, left site = 477 H) than the sites identified by the clinical method (right site = 454.16 H, left site = 436.81 H).

By means of these examinations, it was decided to use the stereolithographic surgical guide during the surgical treatment. With the purpose of identifying the extension of the flap under local anesthesia, we adapted the stereolithographic surgical guide over the mucosa so as to evaluate its fitting on a mucosal surface.

A full-thickness crestal incision was made within the keratinized gin-giva. The mucoperiosteal flap was gently reflected buccally and lingually with a periosteal elevator, taking care not to damage the periosteum and to minimize soft tissue trauma. After mandibular bone surface exposure (Fig. 12), the surgical guide was adapted on the bone surface and the bone drilling was started (Fig. 13). The operative time was relatively short because of precise fitting and no correction was needed.

Fig. 12.
Fig. 12.:
Mandibular bone surface exposure.
Fig. 13.
Fig. 13.:
The template placed on the bone surface allows for precise osteotomy preparation as a result of its stable fit without any movement or rocking.

The divergence test indicated the accuracy of methodology, and the implants had correct directions to support the biting forces (Figs. 14 and 15). Two months later, the implants were successfully loaded.

Fig. 14.
Fig. 14.:
The divergence test during the operation time indicated the accuracy of the stereolithographic methodology.
Fig. 15.
Fig. 15.:
The implants had correct positions and directions to support the biting forces.

Results

This technique, using the stereo-lithographic surgical guide, achieved good results without surgical complications. The time needed for the surgical procedure was relatively short and the guide fitting on the bone surface was excellent during the entire operation. The surgical procedure was simplified, reliable, and easily reproducible. Wound size and bone surface exposure were minimal and no soft tissue trauma was derived by use of burrs during bone drilling. Furthermore, during the operative procedure, there were no major problems of bleeding or nerve lesion. The postoperative time was without complications. The fixtures’ primary stability was predetermined by the evaluation of the bone density, and their distribution was made to support the bite forces. The fixtures’ primary stability permitted reliable oral denture rehabilitation (2 months after operation time). Current clinical guides can offer correct surgical planning but cannot assure predictable surgical results as compared with the stereolithographic guides. 1–14

Discussion

We can consider stereolithography as a remarkable and exciting tool in planning implant surgery. 5–16 The management of patients receiving fixtures requires an adequate study and to achieve good long-term results, optimal planning is a prerequisite. 4–15 The positioning of the implants must be executed not only with respect to the anatomic situation, but also with respect to the prosthetic demands. 15 Many authors 17,18 recommend the use of CT because of the fact that stereolithographic methodology is still a not widespread practice.

This technique offers many advantages: correct management of the tissues with minimal trauma and a superior planned treatment. 6 In cases of severe atrophy, this methodology allows, by the indication of exact surgical limitations, fixture measurements and prevents complications related to poor stability of a denture. 7–13

This technologic improvement can simplify oral management in implant dentistry and avoid complications related to the surgery.

Conclusions

Using Geomagic Studio 4 software, we can evaluate prosthetic stability and consider the load distribution. With this analysis, we have been able to compare (virtually) the prosthetic load obtained with both stereolithographic and clinical implants. The stereolithographic analysis identified a mandibular area that could assure better implant and denture stability; in fact, the triangular plane created with the stereolithographic project is larger and gives more stability to the denture. The patient also experienced shorter surgical procedures and was treated more efficiently using this technique. 5 The results of this study indicate that the combination of the stereolithographic surgical planning process and related surgical techniques are very accurate and are able to assure predictable results. 1–19

Disclosure

The authors claim to have no financial interest in any company or any of the products mentioned in this article.

References

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2. Bill JS, Reuther JF, Dittman W, et al. Stereolithography in oral and maxillo-facial operation planning. Int J Oral Maxillofac Surg. 1995;24:98–103.
3. McAllister MLM. Application of stereolithography to subperiosteal implant manufacture. J Oral Implantol. 1998;26:89–92.
4. Benjamin LS. The evolution of multi-planar diagnostic imaging: predictable transfer of preoperative analysis to the surgical site. J Oral Implantol. 2002;28:135–143.
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10. Swaelens B. Drilling templates for dental implantology. 5th International Workshop Computer Assisted Surgery Henrich Lades; Halle, Germany; October 14–16, 1999.
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15. Kopp CK, Koslow AH, Abdo OS. Predictable implant placement with a diagnostic/surgical template and advanced radiographic imaging. J Prosthetic Dentistry. 2003;89:611–615.
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17. Troulis MJ, Everett P, Seldin EB, et al. Three-dimensional treatment planning system based on computed tomographic data. Int J Oral Maxillofac Surg. 2001;32:45–56.
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19. Andrews JC, Mankovich NJ, Anzai Y, et al. Stereolithographic model construction from CT for assessment and surgical planning in congenital aural atresia. Am J Otol. 1994;15:335–339.

Abstract Translations [German, Spanish, Portugese, Japanese]

AUTOR(EN): Gilberto Sammartino, MS, DDS*, Antonio Della Valle, DMD**, Gaetano Marenzi, DMD, PhD***, Salvatore Gerbino, PhD#, Massimo Martorelli, PhD##, Alessan-dro Espedito Di Lauro, DMD, PhD###, Franscesco Di Lauro, MD, DDS###. *A.O. Professor, ‘Federico II‘ Universität von Neapel, medizinische Fakultät, wissenschaftliche Abteilung Zahnheilkunde und Gesichts- und Kieferchirurgie, Neapel, Italien. ** Privat praktizierender Arzt, Caserta, Italien. *** Student der Oralchirurgie, ‘Federico II‘ Universität von Neapel, medizinische Fakultät, wissenschaftliche Abteilung Zahnheilkunde und Gesichts- und Kieferchirurgie, Neapel, Italien. # Assistenzprofessor, ‘Federico II‘ Universität von Neapel, technische Fakultät, Abteilung für Industrieentwicklung und -management, Neapel, Italien. ## Assistenzprofessor, Universität von Cassino, technische Fakultät, Abteilung für Mechanik-, Struktur-, Territori-alkunde. ### Assistenzprofessor, ‘Federico II‘ Universität von Neapel, medizinische Fakultät, wissenschaftliche Abteilung Zahnheilkunde und Gesichts- und Kieferchirurgie, Neapel, Italien. #### Professor, ‘Federico II‘ Universität von Neapel, medizinische Fakultät, wissenschaftliche Abteilung Zahnheilkunde und Gesichts- und Kieferchirurgie, Neapel, Italien. Schriftverkehr:Gaetano Marenzi, DMD, Via Lepanto 46, 80125 Neapel, Italien. Telefon: +39 - 081 5930107. eMail: [email protected]

Stereolithographie in der Oralimplantologie: ein Vergleich chirurgischer Führungen

ZUSAMMENFASSUNG:Zielsetzung: Die vorliegende Abhandlung stellt die Stereo-lithographie als Einsatzmittel in der Oralimplantologie vor. Die Stereolithographie ist eine neue Methode, bei der durch gezielte Erhärtung eines UV-sensitiven Flüssigharzes ge-genständliche Modelle entstehen, so dass die tatsächlichen anatomischen Gegebenheiten von Ober- und Unterkiefer nachgeahmt werden. Mit Hilfe dieser Modelle können Führungen geschaffen werden, die eine exakt gleiche Setzung der Implantate beim Patienten wie bei der Planungscomputersimulation ermöglichen. Materialien und Methoden: Einer 70 Jahre alten Patientin mit gutem Allgemeingesundheitszustand und schwerer Unterkiefer-knochenatrophie wurde mit einer Deckprothese unter Verwendung von zwei Branemark Implantaten als Stützen behandelt. Für diese Wiederherstellungsbehandlung wurden zwei unterschiedliche operative Planungsmethoden in Erwägung gezogen: a) Herstellung einer chirurgischen Führung unter Auswertung der klinischen Aspekte. b) Die chirurgische Führung als Ergebnis einer stereolithographischen Studie. Ergebnisse: Eine exakte Planung des Chirurgieablaufs kann mit der Knochendichte und den Ausmessungen in Verbindung stehende eventuelle Probleme verringern. Außerdem ist anzumerken, dass die behandelnden Ärzte durch Anwendung der sterolithographischen Studie die Befestigungen ideal im Knochen verankern konnten. Schlussfolgerungen: Basiert man die Operationsvorbereitungen auf stereolithographische Erkenntnisse, kann von einem sicheren Ablauf ausgegangen werden, was viele Vorteile erbringt. Der biologische und therapeu-tische Vorteil dieses technologischen Behandlungsansatzes liegt in der Vereinfachung der anatomischen Behandlungsvorbereitungen bei gleichzeitig verbesserter Implantierungssicherheit.

SCHLÜSSELWÖRTER: Chirurgieplanung, Kieferatrophie, schnelle Prototyperstellung, anatomische Modelle

AUTOR(ES): Gilberto Sammartino, MD, DDS*, Antonio Della Valle, DMD**, Gaetano Marenzi, DMD, PhD***, Salvatore Gerbino, PhD#, Massimo Martorelli, PhD##, Alessan-dro Espedito Di Lauro, DMD, PhD###, Francesco Di Lauro, MD, DDSS. *Profesor Asociado, Universidad de Nápoles ‘Federico II‘, Facultad de Medicina, Departamento de Ciencias Odontológicas y Maxilofaciales, Nápoles, Italia. **Práctica Privada, Caserta, Italia. ***Estudiante de Cirugía Oral, Universidad de Nápoles ‘Federico II‘, Facultad de Medicina, Departamento de Ciencias Odontológicas y Maxilofaciales, Nápoles, Italia. #Profesor Asistente, Universidad de Nápoles ‘Federico II‘, Facultad de Ingeniería, Departamento de Diseño y Gestión Industrial, Nápoles, Italia. ##Profesor Asistente, Universidad de Cassino, Facultad de Ingeniería, Departamento de Mecánica, Estructuras, Territorio. ###Profesor Asistente, Universidad de Nápoles ‘Federico II‘, Facultad de Medicina, Departamento de Ciencias Odontológicas y Maxilofaciales, Nápoles, Italia. §Profesor, Universidad de Nápoles ‘Federico II‘, Facultad de Medicina, Departamento de Ciencias Odontológicas y Maxilofaciales, Nápoles, Italia. Correspondencia a: Gaetano Marenzi, DMD, Via Lepanto 46, 80125 Napoli, Italy. Teléfono: 39-081 5930107, Correo electrónico: [email protected]

Estereolitografía en la implantología oral: Una comparación de guías quirúrgicas

ABSTRACTO:Propósito: Este trabajo presenta el uso de la estereolitografía en la implantología oral. La estereolitografía es una tecnología novedosa que puede producir modelos físicos al solidificar selectivamente una resina líquida sensible a los rayos ultravioletas usando un rayo láser, reproduciendo las dimensiones anatómicas mandibulares y maxilares precisas. Con estos modelos, es posible fabricar guías quirúrgicas que pueden colocar los implantes in vivo en los mismos lugares y mismas direcciones que los de la simulación planeada por computación. Materiales y métodos: Una mujer de setenta años, en buen estado de salud, con una severa atrofia del hueso mandibular fue rehabilitada con una sobredentadura apoyada por implantes Branemark. Se consideraron dos métodos quirúrgicos diferentes: (a) la construcción de una guía quirúrgica evaluando aspectos clínicos.(b) la guía quirúrgica producida por un estudio estereolitográfico. Resultados: La precisión de la planificación quirúrgica puede reducir los problemas relacionados con la densidad y dimensión de hueso. Además, el estudio estereolitográfico aseguró a los clínicos una ubicación superior de los aparatos en el hueso.

Conclusiones: La planificación quirúrgica basada en la técnica estereolitográfica es un procedimiento seguro y tiene muchas ventajas. Este avance tecnológico tiene beneficios biológicos y terapéuticos debido a que simplifica la atención quirúrgica anatómica para mejorar la colocación del implante.

PALABRAS CLAVES: planificación quirúrgica, atrofia de la mandíbula, prototipo rápido, modelos anatómicos

AUTOR(ES): Gilberto Sammartino, Médico, Doutor em Ciência Dentária*, Antonio Della Valle, Doutor em Medicina Dentária**, Gaetano Marenzi, Doutor em Medicina Dentária, PhD***, Salvatore Gerbino, PhD#, Massimo Martorelli, PhD##, Alessandro Espe-dito Di Lauro, Doutor em Medicina Dentária, PhD###, Francesco di Lauro, Doutor em Medicina, Doutor em Ciência Dentárias. *Professor Associado, Universidade de Nápoles “Federico II”, Faculdade de Medicina, Departamento de Ciência da Odontologia e Maxilofacial, Nápoles, Itália. **Clínica Privada, Caserta, Itália. ***Estudante de Cirurgia Oral, Universidade de Nápoles “Federico II”, Faculdade de Medicina, Departamento de Ciência da Odontologia e Maxilofacial, Nápoles, Itália. #Professor Assistente, Universidade de Nápoles “Federico II”, Faculdade de Engenharia, Departamento de Design Industrial e Gestão, Nápoles, Itália. ##Professor Assistente, Universidade de Cassino, Faculdade de Engenharia, Departamento de Mecânica, Estruturas, Território. ###Professor Assistente, Universidade de Nápoles “Federico II”, Faculdade de Medicina, Departamento de Ciência da Odontologia e Maxilofacial, Nápoles, Itália. §Professor, Universidade de Nápoles “Federico II”, Faculdade de Medicina, Departamento de Ciência da Odontologia e Maxilofacial, Nápoles, Itália. Correspondência para: Gaetano Marenzi, DMD, Via Lepanto 46, 80125, Napoli, Italy. Telefone: +39 081 5930107, E-mail: [email protected]

Estereolitografia em Implantologia Oral: Comparação de Guias Cirúrgicas

RESUMO:Objetivo: Este artigo apresenta o uso da estereolitografia em implantologia oral. A estereolitografia é uma nova tecnologia que pode produzir modelos físicos solidificando seletivamente uma resina líquida sensível a UV, usando raio laser, reproduzindo as verdadeiras dimensões anatômicas, maxilares e mandibulares. Com estes modelos, é possível fabricar guias cirúrgicas que podem colocar o implante in vivo nos mesmos lugares e mesmas direções daquelas da simulação por computador planejada. Materiais e Métodos: Uma mulher de setenta anos, com boa saúde e grave atrofia do osso mandibular, foi reabilitada com uma sobredentadura apoiada por dois implantes Brancmark. Dois diferentes métodos de planejamento cirúrgico são considerados: a) A construção de guia cirúrgica avaliando os aspectos clínicos. b) A guia cirúrgica produzida por estudo estereolitográfico. Resultados: A exatidão do planejamento cirúrgico pode reduzir os problemas relacionados com a densidade e as dimensões do osso. Além disso, o estudo estereolitográfico garantiu aos clínicos uma localização superior dos aparelhos no osso. Conclusões: O planejamento cirúrgico baseado na técnica estereolitográfica é um procedimento seguro e tem muitas vantagens. Este avanço tecnológico oferece benefícios biológicos e terapêuticos porque simplifica o manejo anatômicocirúrgico com vistas a uma colocação melhorada do implante.

PALAVRAS-CHAVE: planejamento cirúrgico, atrofia da mandíbula, prototipia rápida, modelos anatômicos.

FIGURE

FIGURE
FIGURE
Keywords:

surgical planning; jaw atrophy; rapid prototyping; anatomic models

© 2004 Lippincott Williams & Wilkins, Inc.