PERIODONTAL HEALTH – CHALLENGES IN RESTORATIVE DENTISTRY J REEVES1
As the population ages and life expectancy increases, clinicians today find themselves in the wake of an ever-growing demand for high-quality aesthetic dental treatment, by increasingly informed patients. The long-term success of both cosmetic and restorative dentistry is dependent on well designed restorations and the health of the periodontal tissues. Overhanging restorations, full crown restorations with poor marginal fit, and implant-supported prosthetics with inadequate hygiene access all increase the risk for periodontal sequelae and interproximal caries. When planning restorative treatment, consideration should be given to the restorative design, the need for hygiene access and the location of intended implants. In addition, the patient’s manual dexterity and ability to manipulate oral hygiene aids is a crucial consideration, as is adequate access for the hygienist to manually debride and maintain the restorations.
Introduction Increasing attention is being given by our patients to their physical health and the desire to live their remaining years feeling well, maintaining a good appearance and a healthy smile. The long-term success of both cosmetic and restorative dentistry is dependent on well designed restorations, and on the health of the periodontal tissues. Restorative dentistry may produce contours that do not always replicate those that occur in the natural dentition. These artificial contours can have adverse effects on the periodontium and surrounding tissues. Common examples include composite restorations that produce excess material, ledges or ‘overhangs’ into the interproximal area (Figure 1). Overhangs can trap plaque and calculus, increasing
Dental hygienist, nutritional consultant
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Composite resin restorations
One of the most important steps in successfully creating composite restorations is contouring, finishing, and polishing. Finishing and polishing the surface greatly increases the functional lifespan of restorations3,4 whilst protecting the patients’ oral health and maximising the aesthetic results.5 A smooth surface reduces bacterial adhesion, resulting in less plaque accumulating on the polished restoration.6,7
There are a number of factors to consider when drawing up a restorative treatment
Figure 1: Overhanging margin
the risk for periodontal sequelae and interproximal caries, as well as making oral hygiene procedures more difficult.1 It is important that restorations are designed to minimise plaque accumulation and maximise access for oral hygiene.
Image courtesy of Dr Frank Goulbourn
plan. At the subject risk level, the patient’s medical and smoking history, oral hygiene and presence of oral parafunction should be considered. It is recognised that some people are more susceptible to chronic inflammation, periodontal and peri-implant diseases than others and factors such as hyperinflammatory phenotype, bone density, morphology, age, manual dexterity and vision are contributory elements. Site-specific risks include periodontal health, pocket depth, attached keratinised mucosa, plaque-retentive elements, exposed implant threads and the presence of bleeding on probing.2
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increased plaque index, gingival index, recession, pocket depth and increased crevicular fluid.13,14
Image courtesy of Dr Frank Goulbourn
To prevent plaque accumulation it is necessary to create optimal crown contours with good coronal form, embrasure form for hygiene access and good fit at the margin. Restorative considerations will frequently dictate the placement of restoration margins; however, placing restorative margins within the biologic width is detrimental to periodontal health and acts as a plaque-retentive factor (see Figure 3).10 This can compromise periodontal health and make access difficult for the hygienist and the patient for home care routines.
Implant placement and prosthetic design Figure 2: Knife-edge margins
Reduction of bacterial adhesion prevents gingival irritation and surface discoloration. A polished surface is more biocompatible with the gingival tissue, thus maintaining gingival health.8 Interproximal surfaces have the maximum potential for plaque retention; removing overhanging margins and polishing interproximal surfaces will significantly lower the patient’s risk for secondary caries and periodontal disease, in addition to improving access for interproximal oral hygiene measures.9
Marginal placement of crowns The most common reasons for gingival inflammation around full coverage crowns include defective margins, poor marginal fit, bulky restoration, poor contours and knife-edge margins. Poorly fitting margins can result in an inflamed, darkened cervical tissue colour and gingival recession, compromising the appearance of the restoration (Figure 2). In order to maintain the health and position of the gingival tissues, critical areas that must be considered include marginal fit, contour and surface finish. Poorly adapted margins, over-contoured or under-contoured
restoration, and rough or porous surfaces can cause inflammation, gingival recession or overgrowth. Open margins can provide a niche for microorganisms and potentiate the inflammatory response.10 The placement of crown margins is one of several parameters that affect gingival health.11 The most common finding with deep margin placement is the development and persistence of gingival inflammation around the restoration.12 Research has also revealed that subgingival restorations demonstrate changes in the microflora,
Bacterial infection is the biggest risk factor for periodontal and peri-implant diseases. The formation of a biofilm plays a significant role in the initiation and progression of peri-implant diseases and is essential to the development of infections around dental implants.15,16 Colonisation occurs rapidly post-placement. Glycoproteins from saliva adhere to exposed titanium surfaces with concomitant microbiological colonisation. There is a shift towards gram-negative proliferation and thickening of the biofilms as the disease progresses.17,18
Brunsvold MA, Lane JJ. The prevalence of overhanging dental restorations and their relationship to periodontal disease. J Clin Periodontol 1990 Feb;17(2):67-72. Gross M. Clinical dilemmas: restoration of posterior quadrants in the partially edentulous dentition – 9year retrospective cumulative study. Warsaw, IN: Zimmer Dental; 2013. Available at: http://www.zimmerdental.co.uk/Library/lib_artGross .aspx Accessed: 28 Dec 2013. Turkun LS, Turkun M. The effect of one-step polishing system on the surface roughness of three esthetic resin composite materials. Oper Dent 2004;29(2):203-211. Mopper KW. How do composite resins stand the test of time? Dent Today 2004;23(5):74-79.
Jefferies SR. Abrasive finishing and polishing in restorative dentistry: a state-of-the-art review. Dent Clin North Am 2007;51(2):379-397. Ikeda M, Martin K, Nikaido T, Foxton RM, Tagami J. Effect of surface characteristics on adherence of S. mutans biofilms to indirect resin composites. Dent Mater J 2007;26(6):915-923. Kantorski KZ, Scotti R, Valandro LF, Bottino MA, Koga-Ito CY, Jorge AO. Adherence of Streptococcus mutans to uncoated and saliva-coated glass-ceramics and composites. Gen Dent 2008:56(7)740-747. Mopper KW. Let’s talk composites! Dent Today 2008;27(10):120-122. Rodriguez-Ferrer HJ, Strahan JD, Newman HN. Effect of gingival health of removing overhanging margins of interproximal subgingival amalgam restorations. J Clin Periodontol 1980;7(6):457-62.
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Figure 3: Dental biologic width
In periodontitis the inflammatory process is a “self limiting” process, being contained by the presence of the periodontal ligament. However, the base of the pocket in the case of peri-implantitis does not have an epithelial component; hence, the disease progresses apically more rapidly, with more advanced inflammatory cell infiltration in the peri-implant mucosa.19 The absence of a periodontal ligament therefore means that the inflammatory reaction is intimately associated with the implant surface and bone, with no protective element.20 There is evidence that peri-implant mucositis is reversible when effectively treated.16,21 Early diagnosis renders treatment more likely to succeed; however, diagnosis and management may be complicated by elaborate superstructures or poor prosthetic design.22 It is therefore essential to make oral hygiene measures simple and effective, as poor access for plaque control around the suprastructure decreases the odds of implant survival.
Single tooth restorations The single tooth restoration has become one of the most widely used procedures in implant dentistry. Improvements to the abutment-implant interface design, wider implant platforms and the increased use of cemented restorations have improved this procedure.
10 Shenoy A, Shenoy N, Babannavar R. Periodontal considerations determining the design and location of margins in restorative dentistry. J Interdiscip Dentistry 2012;2:3-10. 11 Reitemeier B, Hänsel K, Walter MH, Kastner C, Toutenburg H. Effect of posterior crown margin placement on gingival health. J Prosthet Dent 2002;87(2):167-72. 12 Waerhaug J. Healing of the dento-epithelial junction following subgingival plaque control. II: As observed on extracted teeth. J Periodontol 1978;49:119–34. 13 Valderhaug J, Birkeland JM. Periodontal conditions in patients 5 years following insertion of fixed prostheses. Pocket depth and loss of attachment. J Oral Rehabil 1976;3:237–43. 14 Newman MG, Takei H, Klokkevold PR, Carranza FA. Carranza's Clinical Periodontology. 10th ed. Philadelphia: Saunders Elsevier; 2006. pp.1050–69.
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One of the biggest challenges when replacing a multi-rooted molar tooth is that the implant diameters are narrower than the original root. The mesio-distal dimensions of a molar exceed that of most standard implants (3.75-4 mm).23 Where the circumference of the crown is greater than the supporting abutment, a large discrepancy between implant and restoration size is created. This results in a bell shaped or ridge lapped crown, producing a broad surface of restorative material in contact with the soft tissue, leading to poor aesthetics and limited access for oral hygiene.24 A discrepancy in size between the width of the required restoration and the diameter of the implant also affects the emergence profile.
15 Mombelli A, Lang NP. The diagnosis and treatment of peri-implantitis. Periodontol 2000 1998;17:63-76. 16 Pontoriero R, Tonetti MP, Carnevale G, Mombelli A, Nyman SR, Lang NP. Experimentally induced periimplant mucositis. A clinical study in humans. Clin Oral Implants Res 1994;5:254-259. 17 Quirynen M, Vogels R, Peeters W, van Steenberghe D, Naert I, Haffajee A. Dynamics of initial subgingival colonization of “pristine” peri-implant pockets. Clin Oral Implants Res 2006;17:25-37. 18 Heitz-Mayfield LJ, Lang NP. Comparative biology of chronic and aggressive periodontitis vs. peri-implantitis. Periodontol 2000 2010;53:167-181. 19 Zitzmann NU, Berglundh T, Ericsson I, Lindhe J. Spontaneous progression of experimentally induced periimplantitis. J Clin Periodontol 2004;31:845-849. 20 Berglundh T, Zitzmann N, Donati M. Are peri-implantitis
The emergence profile of an implant abutment and restoration is important for both aesthetic and oral hygiene considerations. Photographic analysis of natural teeth by Croll25 confirmed that most emergence profiles are relatively straight as opposed to convex or concave. If a restoration creates a convexity or concavity, this may favour bacterial biofilm accumulation and restrict appropriate hygiene access, predisposing the soft tissues to inflammation and potential failure of the implant.26 Anatomical emergence closely replicates the natural orientation of the root which once occupied the original socket. The transmucosal abutment emerges from the gingiva and is continuous with the crown it supports. The crown does not come in contact with the ridge, and provides a space to accommodate oral hygiene aids.27 In the posterior segment, where aesthetics are not as critical, a crown form designed with hygiene access is the most compatible with function and maintenance.28 The access procedures for maintenance of a single implant with anatomical emergence contours may resemble the procedures used for a natural tooth with an anticipated high degree of success.29 The prosthetic need for a modified ridge lap occurs when an implant is unable to closely
lesions different from periodontitis lesions? J Clin Periodontol 2011;38(suppl.11):188-202. Salvi GE, Aglietta M, Eick S, Sculean A, Lang NP, Ramseier CA. Reversibility of experimental peri-implant mucositis compared with experimental gingivitis in humans. Clin Oral Implants Res 2012;23:182-190. Serino G, Strom C. Peri-implantitis in partially edentulous patients: Association with inadequate plaque control. Clin Oral Implants Res 2009;20:169-174. Moscovitch M. Molar restorations supported by 2 implants: an alternative to wide implants. J Can Dent Assoc 2001;67(9):535-9 Graves SL, Jansen CE, Siddiqui AA, Beaty KD. Wide diameter implants: indications, considerations and preliminary results over a two-year period. Aust Prosthodont J 1994; 8:31–7. Croll BM. Emergence profiles in natural tooth contour.
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resemble the size and/or position of the root which it replaces. Both modified and full ridge lap techniques result in gingival tissue being covered by the contours of the crown, resulting in plaque-retentive areas created by the transmucosal abutment and crown. Each of these designs presents challenges for both the hygienist and the patient, as they may impede the removal of the plaque and calculus which accumulate underneath the restoration.30,31
Residual cement Fixed implant restorations are either screw-retained or cement-retained, and each technique has its advantages and disadvantages. The choice of restorative fixture will often be governed by aesthetics. Peri-implant disease and infection due to cement residue is an emerging area of concern.32 Incomplete removal of cement left in the subgingival space is quite plausible due to implant positioning and the subsequent suprastructure design. In addition, many commonly used cements are undetectable by radiographic surveillance.33 If an abutment with a fixed restorative margin 2-3 mm above the implant collar is used, or if a one-piece implant with a builtin restorative margin is used, the potential for excess cement removal is made more difficult in the deep tissue cuff.34 Peri-implant disease or implant failure can result when cement residue is not removed35 and may hamper mechanical nonsurgical therapy efforts to access the subgingival
Part II: Clinical considerations. J Prosthetic Dent 1990;63(4):374-379. O’Mahony A, MacNeill S R, Cobb CM: Design features that may influence bacterial plaque retention: A retrospective analysis of failed implants. Quintessence G Int 2000;31:249-256 Eissmann HF, Radke RA, Nobel WH. Physiologic design criteria for fixed dental restoration. Dent Clin North Am 1971;4:5543-568. Johnson GK, Leary JM. Pontic design and localized ridge augmentation in fixed partial denture design. Dent Clin North Am 1992;36(3):591-605. Salierno C: The implant dilemma. Registered Dental Hygienist 2012;32(6):28-32. Cavazos E. Tissue response to fixed partial pontics. J Prosthet Dent 1968;20:143-153.
space.36 Wilson32 demonstrated that suppuration or continued bleeding on probing around the gingival margins of implant restorations had an 81% correlation to the presence of excess cement. The presence of excess cement in itself may induce inflammation; however, the surface roughness may also provide the medium for bacterial colonisation. Clinical signs of subgingival cement include soft tissue swelling, soreness, bleeding and/or exudate on probing.37 The clinical consequences of cement peri-implantitis may include crestal bone loss, loss of gingival support, and potential acute abscess, putting the survival of the implant and restoration at risk. Predisposing factors include the weak hemidesmosomal attachment to the transmucosal collar, which may be less resistant to the pathological changes associated with excess cement retention. The shared maintenance responsibility between the implant surgeon, the restorative dentist and the dental hygienist must include clinical gingival inspection, radiographic comparison, monitoring occlusal forces to prevent occlusal overload issues, and considering pathological changes from retained excess cement.38
restorative design, the need for hygiene access and the location of intended implants. In addition, the patient’s manual dexterity and ability to manipulate oral hygiene aids is crucial, as is adequate access for the hygienist to manually debride and maintain the restorations. When considering the provision of composite restorations or crown and bridge design, the creation of interproximal space between mesial and distal embrasure areas will allow the passage of floss, small interdental brushes or oral irrigators. It is particularly important to allow hygiene access when implants emerge through poorly keratinised unattached mucosa. Oral hygiene procedures are much easier and more comfortable for the patient to perform when the implants are surrounded by keratinised attached mucosa. Access for both the hygienist and patient must be provided for effective removal of plaque and food debris from around the abutments and above fixed prosthetic frameworks. Failure to provide adequate access renders the patient susceptible to plaque accumulation and potential failure of the implant.
The prevention of periodontal and periimplant diseases is fundamental to the long-term function of aesthetic restorations and implant supported prostheses. When planning restorative treatment, consideration should be given to the
Repeated maintenance visits, patient cooperation and motivation are all important for improved success of restorative procedures. Keeping prosthetic design as simple as possible for hygiene access will help both the hygienist and patient to maintain beautiful restorations with aesthetics, function and excellent periodontal health.
31 Liu CL. Use of a modified ovate pontic in areas of ridge defects: a report of two cases. J Esthet Restor Dent 2004;16:273-281. 32 Wilson TG Jr. The positive relationship between excess cement and peri-implant disease: A prospective clinical endoscopic study. J Periodontol 2009;80:1388-1392. 33 Wadhwani C, Hess T, Faber T, Piñeyro A, Chen CSK. A descriptive study of the radiographic density of implant restorative cements. J Prosthet Dent 2010;103:295-302. 34 Dumbrigue HB, Abanomi AA, Cheng LL. Techniques to minimize excess luting agent in cement-retained implant restorations. J Prosthet Dent 2002;87(1):112-114. 35 Linkevicius T, Puisys A, Vindasiute E, Linkeviciene L, Apse P. Does residual cement around implant-
supported restorations cause peri-implant disease? A retrospective case analysis. Clin Oral Impl Res 2013;24:1179–1184. 36 Maximo MB, de Mendonca AC, Santos RV, Figueiredo LC, Feres M, Duarte PM. Short-term clinical and microbiological evaluations of periimplant diseases before and after mechanical anti-infective therapies. Clin Oral Implants Res 2009;20:99-108. 37 Pauletto N, Lahiffe BJ, Walton JN. Complications associated with excess cement around crowns on osseointegrated implants: A clinical report. Int J Oral Maxillofac Implants. 1999;14(6):865-868. 38 Shapoff CA, Brent JL. Crestal bone loss and the consequences of retained excess cement around dental implants. Compend Contin Educ Dent 2012;33(2):94-6,98-101.
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