MCQs in Implant Dentistry

By Akeel Mosea

The MCQs in Implant Dentistry is a comprehensive review book that covers most aspects of implant dentistry. It uses questions based on real clinical scenarios with extensive answers based on textbooks and modern literature. The reader will gain a broad understanding of the scientific basis of dental implants, treatment planning, identification of high risk occlusal forces, managing cantilevers, applied anatomy, biological aspects of dental implants and bone healing, prosthetic components, impression techniques and materials, bone augmentation techniques, different types of bone grafts, autogenous bone graft techniques, calcium metabolism, suture materials, local anaesthetic drugs, nerve injury, medication related osteonecrosis of the jaw, peri-implantitis and implant protected occlusion. The second edition is a refinement. We also delved into the concept of prosthetically driven implant placement, digital dentistry, and timings of implant placement. The target audience should be dentists with or without prior experience in dental implants, oral and maxillofacial surgeons and even dental nurses. The book will be of particular interest to candidates sitting exams.

• Language: English
• Publisher: Lulu.com
• Release date: Jul 8, 2020
• ISBN: 9781716771286

Book preview

Copyright © 2016 Akeel Mosea

All rights reserved, including the right to reproduce this book, or portions thereof in any form. No part of this text may be reproduced, transmitted, downloaded, decompiled, reverse engineered, or stored, in any form or introduced into any information storage and retrieval system, in any form or by any means, whether electronic or mechanical without the express written permission of the author.

978-1-716-77128-6

Imprint: Lulu.com

This work is dedicated to my parents, my wife and my children

Preface to second edition

It has been almost seven years since the MCQs in Implant Dentistry was launched. I was incredibly pleased with the positive feedback we received worldwide, so many thanks to our readers.

Indeed, this has inspired me to develop the book further to keep our readers up to date with literature in dental implantology. We have added more questions and clinical scenarios.

The spirit of the book in its second edition remains the same; It is simple to read, thorough, and rich in illustrative pictures and diagrams. We have also refined the old content and produced an E-book format.

Many thanks for your time reading this book.

Akeel Mosea

United Kingdom 2023.

Preface

A year ago, I launched my first book titled MCQs in Plastic Facial Skin Reconstruction, I would like to thank all of my colleagues who supported me, read the book or left feedback.

Here we are again! This time with a different subject but still within the Oral and Maxillofacial surgery umbrella. The MCQs in Implant Dentistry has been written to help dental surgeons with or without prior implant experience to understand, and apply the principles of implant dentistry in their daily practice. It can also be an invaluable aid for candidates sitting exams.

During my preparation for the wonderful programme of the Diploma in Dental Implants at the Royal College of Surgeons in England, I came across hundreds of literature papers. I found it amazing how some issues in dental implants can be debatable. Therefore, I decided to put everything together in a well-researched, compact and easy to read book. However, the reader is strongly encouraged to read any up-to-date literature as the science of dental implants can rapidly change.

Finally, I would like to thank Dr. Min Patel BDS (Hons). FDSRCS. Dip.Imp.Dent. DHLM for her ongoing support, and kindly reviewing the book.

Akeel Mosea

Questions and Answers

1. One of the following materials can be a reliable alternative to titanium dental implants in patients who are allergic to titanium:

a. Cobalt-Chromium-Molybdenum(Co-Cr-Mo) alloys.

b. Iron-Chromium-Nickel(Fe-Cr-Ni) alloys.

c. Zirconium ceramics.

d. Platinum.

e. None of the above.

1. Answer: c

Allergic reactions to titanium are very rare. However, cellular sensitization and reports of nonspecific immunomodulation and autoimmunity have been reported. In addition, titanium is dark grey in colour which may show through thin peri-implant tissues.

Zirconia is a type of bio-inert ceramics. It appears to be a suitable dental implant material with osseointegration which might be comparable to titanium. It also has a tooth like colour, good mechanical properties and bio-compatibility. Most of Zirconia dental implants come in one piece (fixture fused to abutment). Studies showed cumulative survival rate was comparable to that of titanium implants when immediately restored. However, there are some reports of increased radiographic bone loss after one year of placement compared to 2-piece titanium implants. Modification of implant surface i.e., Sandblasting or acid etching can be more difficult to achieve in zirconia implants.

Although zirconia may be used as an implant material by itself, zirconia particles are also used as a coating material on titanium dental implants. A sandblasting process with round zirconia particles may be an alternative surface treatment to enhance osseointegration of titanium implants

The obsolete subperiosteal implants and the ramus blade implants were made of Cr-Co-Mo and Fe-Cr-Ni alloys respectively.

Ref:

Őzkurt Z, Kazazoglu E. Zirconia Dental Implants: A Literature Review. Journal of Oral Implantology: June 2011, Vol. 37, No. 3, pp. 367-376.

Kohal RJ, Knauf M, arson B, Sahlin H, Butz F. One-piece zirconia oral implantts: one year results from a prospective cohort study. Single tooth replacement. J Clin Periodontol. 2012 Jun;39(6):590-7.

Muddugangadhar BC, Amarnath GS, Tripathi S, Dikshit S, Divya MS. Biomaterials for dental implants: An overview. Int J Oral Implantology Clin Res 2011;2(1):13-24.

2. Which one of the following represents a bio-mimetic modification of an implant surface:

a. TPS (Titanium Plasma Spray).

b. Electrochemical anodization.

c. Sandblasting with silica (sand), alumina or titanium oxide.

d. Acid etching.

e. None of the above.

2. Answer: e

The shape and quality of implant surface are major factors that influence primary stability, wound healing and osseointegration. Dental implant shape and surface modifications can be achieved at 3 levels: macro, micro and nano levels.

Macro properties:

Dental implant body is composed of coronal and apical parts. The coronal part often has parallel walls for stability and surgical simplicity. The apical end of the implant is often tapered to ease surgical placement because it fits within the osteotomy hole before it engages the walls of the bone. An anti-rotation mechanism is often incorporated into the apical part of the implant to resist torsion forces. This can be a hole or vent in which bone can grow and resists torsion forces. However, a vent can attract infections  if the implant has perforated the sinus floor. Another anti-rotational feature can be a flat surface along the apex of the implant. Bone growing against this flat surface will resist rotational forces. In addition, this design feature will enhance the self-tapping property of the implant fixture. Finally, the apex of an implant should not be pointed to avoid stress concentration and to decrease discomfort to the soft tissues should the implant perforate the cortical plate.

Implant body shape: cylinder shaped implants offer ease of insertion, especially in dense bone as bone tapping is not needed. However, this type of implants often needs some form of bioactive or rough coating to increase the surface area. Reports show poor long-term survival in these implants probably due to shear forces they transmit to the bone after occlusal loading . Screw shaped body is the most common shape. It allows placement in both soft and hard bone by modifying the osteotomy technique i.e., bone tapping in the hardest bone and self-tapping in soft bone. Depending on threads geometry, this type of implant can transmit compressive, tensile or shear forces to the bone.

Machined Vs roughened surface: more Bone to Implant Contact (BIC) can be achieved with roughened implant surface.

Thread geometry: square, V-shaped, buttress or reverse buttress. Square thread can provide the most BIC. It can also transmit a compressive type of force to the bone when the implant is loaded in an axial direction. However, the other thread designs can transmit tensile or shear type of force to the bone/implant interface when the implant is loaded axially. Studies showed that bone is 65% weaker to shear forces compared with compression loads and 35% weaker compared with tensile loads.

Thread pitch: The number of threads per unit length.

Thread depth: The distance between the major and the minor diameter of the threads.

C:\Users\AKEEL\Documents\Documents\MCQIMPLANTS\Untitled.png

Functional surface area (and eventually BIC) of a screw type implant can be increased with square type threads, higher number of threads, smaller thread pitch and deeper threads.

Micro properties

Surface topography of titanium can be modified by different treatments, in order to obtain a surface with specific properties, which have direct influence on the process of osseointegration. These methods can be:

Additive: i.e., Titanium Plasma Spray (TPS), bioactive materials coating like Hydroxyapatite (HA) / Calcium Phosphate (CaP) ceramic coatings which chemically bonds with the adjacent bone and act as an osteoconductive material. However, delaminating of this coating has been blamed as a cause of failure in such implants. Additionally, the transmucosal zone of HA implants represents a challenge in terms of peri-implantitis. Recently, biomimetic coatings have been applied on titanium dental implants to enhance the initial biological response i.e., Bone Morphogenic Proteins rhBMP-2.

Subtractive: grit blasting titanium surface with silica (sand), alumina, titanium oxide, or CaP.

A great part of commercially available grit blasted implants are eventually acid etched. Another method is electrochemical anodization. The combination of potentiostatic or galvanostatic anodization of titanium in strong acids at high current potential results in thickening of the titanium oxide layer which  has a considerable osteoconductive potential.

Ref:

Misch, Carl E. Dental Implant Prosthetics. St. Louis, MO: Elsevier Mosby, 2015. Chapter 15.

Novaes Jr, A. B., Souza, S. L. S. D., Barros, R. R. M. D., Pereira, K. K. Y., Iezzi, G., & Piattelli, A. (2010). Influence of implant surfaces on osseointegration. Brazilian dental journal, 21(6), 471-481.

3. Which one of the following implant thread designs transmits primarily a compressive force to the bone on axial loading?

C:\Users\AKEEL\Documents\Documents\MCQIMPLANTS\threads.jpgC:\Users\AKEEL\Documents\Documents\MCQIMPLANTS\threads2.jpg

a. A.

b. B.

c. C

d. D

e. A and C.

3. Answer: e

Threads in dental implants have three functions : to maximize initial contact (for primary stability), enhance functional surface (for osseointegration) and facilitate dissipations of stress at the interfacial area (occlusal loading forces on the implant).

Square or buttress shaped threads transmit more of compressive forces to the bone when the implant is axially loaded. On the other hand, V-shaped threads and the similar looking reverse buttress thread implants transmit more shear load to the bone. This can be significant especially in low density bone in the posterior maxilla and when using short implants because bone is least resistant to shear forces, which may lead to resorption and decreased bone to implant contact. The pictures below demonstrate the force direction along different types of implants threads.

C:\Users\AKEEL\Documents\Documents\MCQIMPLANTS\bonestress.png

Square Vs V-shaped

C:\Users\AKEEL\Documents\Documents\MCQIMPLANTS\bonewsress2.png

Buttress Vs reverse buttress

Ref:

Rismanchian M, Birang R, Shahmoradi M, Talebi H, Zare RJ. Developing a New Dental Implant Design and Comparing its Biomechanical Features with Four Designs. Dental Research Journal. 2010;7(2):70-75.

Misch, Carl E. Dental Implant Prosthetics. St. Louis, MO: Elsevier Mosby, 2015. Chapter 15.

4. One of the following statements is true regarding one-piece dental implant:

a. Is indicated in soft bone i.e., posterior maxilla as it usually has an aggressive threads pattern.

b. Selection criteria are more critical than 2-piece implants.

c. The implant should be submerged if there is a concern regarding primary stability.

d. Open tray impression technique should be used to construct the prosthetic part.

e. All of the above.

4. Answer: b

The implant and the abutment are fused in one-piece dental implant. It can be made of titanium or zirconia. Often this type of implant can be placed in a flapless procedure and loaded immediately. Because they are always placed in a trans mucosal manner, there is no need for a second stage surgery, so it can simplify the treatment. Prosthetic part can be constructed using a conventional crown and bridge impression after trimming the abutment into the right shape. Opposite to 2-piece implant, there is no loosening or breaking of the abutment screw. Zirconia implants are mostly one-piece implants because fine scale structures are more difficult to manufacture.

The downside of one-piece implant is that the selection criteria can be more critical. It is best suited for cases where the implant and the crown share a similar long axis and the bone quantity and quality allows immediate loading. One-piece dental implant has no micro gap and therefore does not display bacterial colonization at the implant-abutment interface. Limited literature reveals many positive but also some negative results regarding the effects of a one-piece implant on the surrounding hard and soft tissues.

Ref:

Prithviraj DR, Gupta V, Muley N, Sandhu P. One Piece implants: placement timing, surgical technique, loading protocol, and marginal bone loss. J Prosthodont 2013 Apr;22(3):237-44.

5. The following diagram shows 4 different types of implant fixtures:

One of the following is correct:

a. Implant B is better suited for immediate loading than implants A and C.

b. Implants C is contraindicated in the aesthetic zone.

c. Implants C must have the shiny part always above the bone level.

d. Implant D is indicated for thin biotypes.

e. a and d.

5. Answer: e

The above implants have different designs and are made of different materials. Implants A, B and C are made of titanium while implant D is a one-piece ceramic implant (made of zirconium).

Implants A and B are also called bone level (BL) implants. The implant shoulder is ideally placed at the bone level or sub crestal, depending on the manufacturer recommendations. The prosthodontic platform and emergence profile in BL implants is determined by the abutment.

Implant C is also called tissue level (TL) implant, the shiny polished tulip-like shoulder provides the prosthodontic platform with a pre-determined emergence profile for the implant (less

Reviews for MCQs in Implant Dentistry

[Huzaifa · Rating: 5 out of 5 stars]

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[Fatma · Rating: 5 out of 5 stars]

Amazingly practical, summarised and condensed knowledge with easy expanatory language!!! I really appreciate a lot and please accept my sincere gratitude ..