|Year : 2015 | Volume
| Issue : 2 | Page : 122-129
Clinical considerations in restorative dentistry - A narrative review
Ashwini Tumkur Shivakumar1, Sowmya Halasabalu Kalgeri1, Sangeeta Dhir2
1 Department of Conservative Dentistry and Endodontics, Jagadguru Sri Shivarathreeshwara Dental College and Hospital, Mysore, Karnataka, India
2 Department of Periodontology and Implantology, Dr. Bhimrao Ramji Ambedkar Institute of Dental Sciences, Patna, Bihar, India
|Date of Web Publication||3-Sep-2015|
Dr. Ashwini Tumkur Shivakumar
Department of Conservative Dentistry and Endodontics, Jagadguru Sri Shivarathreeshwara Dental College and Hospital, Mysore - 570 015, Karnataka
Source of Support: None, Conflict of Interest: None
| Abstract|| |
The relationship between periodontal health and the restoration of teeth is intimate and inseparable. Human teeth are designed in such a way that the individual tooth contributes significantly to their own support as well as collectively the teeth in the arch. Decay on the proximal surfaces occurs mainly due to the faulty interrelationship between the contact area, marginal ridge, the embrasures and the gingiva. An adequate understanding of the relationship between periodontal tissues and restorative dentistry is paramount to ensure an adequate form, function, aesthetics and comfort of the dentition. For long-term survival of restoration, both functionally and esthetically, certain biological considerations are very critical to preserve the health of the periodontium and thus must be given due importance in clinical practice. While most clinicians are aware of this important relationship, uncertainly remains regarding specific concept such as biologic width and its maintainces.
Keywords: Biologic width, contact and contours, marginal ridge, occlusal forces
|How to cite this article:|
Shivakumar AT, Kalgeri SH, Dhir S. Clinical considerations in restorative dentistry - A narrative review. J Int Clin Dent Res Organ 2015;7:122-9
|How to cite this URL:|
Shivakumar AT, Kalgeri SH, Dhir S. Clinical considerations in restorative dentistry - A narrative review. J Int Clin Dent Res Organ [serial online] 2015 [cited 2019 Aug 20];7:122-9. Available from: http://www.jicdro.org/text.asp?2015/7/2/122/164377
| Introduction|| |
Optimizing tooth form has always been the "holy grail" of restorative dentistry. Recreating the missing tooth anatomy is important not only to replace the lost tooth structure but also to re-establish ideal form and function. 
Successful restorative dentistry can be accomplished when there is a healthy and stable supporting tissue surrounding the tooth; close attention to both hard tissue and soft tissue during and after restorative procedures will greatly increases the probability of successful outcome. 
Restoring the proper anatomy of the tooth and maintaining the health of the soft tissue should be a prime consideration during the restorative procedure. This article reviews the clinical considerations that need to be adopted while restoring a natural tooth and or implant restoration.
| Patient Evaluation|| |
A through examination is necessary to provide comprehensive dental care the patient so as to establish a good oral health. A review of general medical status and past dental history is necessary as it influences the treatment plan.
Review of general health helps to identify systemic health problem that may modify the dental treatment that is necessary. Common communicable diseases such as herpes simplex, chicken pox, mumps, etc. should be diagnosed and special infection control measures or delaying the treatment may be required.
Drug allergies and systemic health should be elicited from the patient prophylactic antibiotic coverage must be provided prior to the treatment. Conditions like uncontrolled diabetics and hypertensive or those on immunosuppressive therapy (transplant patients) should be referred to physician consult before dental treatment. 
Hard tissue and soft tissue examination intraorally is a must for proper treatment planning. [Table 1] explains the overview of the clinical examination. 
Material options for restoring a teeth
Generally, choice of dental filling material should be based on the patient's case history, clinical, radiographic and other relevant findings. The dentist must decide whether or not to restore the tooth and, if restoration is required, which restorative material to employ for the anticipated situation.
Deciding factors for restorative treatment 
- Extent of caries.
- Strength of remaining tooth structure.
- Specific characteristics of the patient's dentition and periodontal health.
- Patient's oral hygiene and dental caries history.
- Financial costs of the procedure to the patient.
- Risks and benefits of the procedure to the patient.
- Ability of the dentist to perform the procedure.
- Preferences of the dentist and the prevailing standard of care.
- Acceptance by the patient.
Although caries is the predominant reason for restoration of teeth, several other clinical conditions, such as tooth fracture, restoration failure, and trauma, also may require restoration. The most common clinical conditions, treatment options, and restorative material options are summarized in [Table 2]. 
|Table 2: Indications, treatment, and restorative material options for the restoration of posterior teeth|
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| Direct and Indirect Restorative Materials|| |
Direct materials are those that can be placed directly in the tooth cavity during a single appointment. Indirect materials are used to fabricate restorations in the dental laboratory that then are placed in or on the teeth; placement of indirect materials generally requires two or more visits to complete the restoration. [Table 3] lists the commonly used direct and indirect restorative material. 
The life of dental restoration depends on material and procedure, size and location of the restoration, chewing habits, oral hygiene and its maintenance, and systemic conditions. Material related factors include strength; wear resistance, tolerance to water, dimensional stability and colour stability. Because each restoration has unique circumstances that profoundly affect its lifetime. This article does not attempt to discuss or predict longevity of service for any of these materials but it discus about restabilising a single tooth in proper form and function.
Re-establishing the anatomy of the tooth Contact and contours
Establishing the interproximal contact is the primary objective of restorative procedures.  Ideal Proximal contact acts as a barrier against food impaction and thus contributes to underlying periodontal health.  By providing food spillway and facilitating hygienic cleaning.
Contact point has been defined as the point when teeth erupt and acquire proximal contact with adjacent tooth proximal attrition leads to the conversion of contact point to contact area.
The proximal contact or the contact area refers to the surface area where the proximal surfaces of neighboring teeth come in contact. Contact area is usually located in upper one third of the crown of most of the tooth. 
Creates a natural embrasure providing a opportunity for good maintenance of the interproximal area.
An ideal contact serves by:
- Maintaining the dental arch stability by transmitting the force along the long axis of the teeth. 
- The correct relationship with the adjacent tooth allows a good support against masticatory forces and promotes the deflection of the food through the embrasure. 
- Influences speech and cosmetics especially in the anterior region. 
Improper restoration in the contact area will cause displacement of the teeth, lifting forces of the teeth, rotation of the teeth, deflecting occlusal contact and food impaction. 
Disadvantages of improper contact areas
Faulty contacts leads to restorative defects which hampers the health of the periodontium:
- Too broad contact bucco-lingually or occlusal-gingivally causes change in the tooth anatomy, improper shunting of food in bucco-lingual direction because of narrow embrasure this leads to food impingement in the contact area and contact area which is more concave (or flat) can be broad which will result in improper physiological movement of the tooth. ,
- Too narrow contact bucco-lingually or occluso-gingivally causes food impaction vertically and horizontally which leads to wide embrasure in which lead to greater food retention and plaque accumulation and contact area which is more convex will diminish the extent of the contact area. ,
- Contact area placed too occlusally, bucally or lingually will result in flattened marginal ridge of the restoration, Contact point too gingivally will lead to increased depth of occlusal embrasure, loose contact creates continuity between embrasure leading to food impaction. 
It is not uncommon to observe good proximal contact but in adequate contour in proximal restoration. Similarly a good contour with the poor proximal contact exits can be possible. 
Each tooth exhibits contour in the form of concavity and convexity. Facial and lingual convexities of the tooth holds the gingival under tension and also protects the gingival margin by deflecting the food away.  The over convexities can create a favourable environment for the growth of microorganisms. 
A facial and lingual concavity helps in occlusal static and dynamic relation, as they determine the pathway of mandibular teeth into and out of centric occlusal. Deficiency of this concavity will inhibit the physiological movements. ,
In addition to creating a contact area of proper size, location and configuration, it is also essential to restore the proximal surface to a proper contour. Fabricating a restoration that does not reproduce the concavities and convexities which occur here naturally will lead to overhanging or under hanging restorations which leads to periodontal damage. 
Clinical impression suggests loose or open proximal contact to be the contributing factors to periodontal pocket formation. It is still generally accepted that a good contour and a tight proximal contact are important for gingival health. 
Marginal ridges of the posterior tooth are considered to be of a primary importance in providing structural strength to crown.  It has a greater thickness of enamel than other areas. Loss of one or more marginal ridge weakens the tooth. 
It is imperative to have a marginal ridge of proper dimension, compatible to the occlusal anatomy creating a pronounced adjacent triangular fosse and occlusal embrasure. Marginal ridge should always form in two planes bucco-lingually meeting at a very obtuse angle. This feature is essential when an opposing functional cusp occludes with the marginal ridge. These essential features are necessary to prevent food lodgement which causes damage to the periodontium.
There are two forces acting on two marginal ridges, force 1 and 2 which have their horizontal components, 1H and 2H drive the two teeth towards each other, thus preventing any proximal impaction of food.  The vertical forces 1V and 2V which are acting vertically are resolved normally by the underlying tissue [Figure 1].  Marginal ridge portion of the restoration should be compatible with the adjacent marginal ridge, both the ridges should be approximating at the same level and display correct occlusal embrasure for the passage of the food to facial and lingual surface. 
Criteria's for restorations of marginal ridge:
- In the absence of marginal ridge:
The forces 1will be directed towards the proximal ridge of the adjacent tooth and force 2 is directed on to the same tooth, so the horizontal forces 1H and 2H will act on the same tooth, which will tend to drive the two teeth away from each other. The vertical component 1V and 2V can impact the food intraorally [Figure 2].
- Adjacent marginal ridge not compatible with height:
Restoring the marginal ridge higher than the adjacent one will allow force1 (A) on the proximal surface of the restoration, the horizontal component 1H (AH) will drive the restored tooth away from the contacting tooth and the vertical component will push debris interproximally even in the presence of force 2 (B) with its horizontal component (BH) acting on the adjacent marginal ridge there is some separation of the teeth as force 2(B) is too small as compared to force 1 (A). By restoring the marginal ridge lower than the adjacent one we can expect the same movement of the tooth but the major movement will be non restored tooth [Figure 3]a and b.
- Marginal ridge with no triangular fossae:
In this situation there are no occlusal plans in the marginal ridges, so there are no occlusal forces acting 1 and 2, so there are no horizontal component 1H and 2H to drive the tooth toward each other and vertical force 1V and 2V will impact the food interproximally [Figure 4].
- Single planed marginal ridge in bucco-lingual direction
This can create the premature contact during both function and static occlusion, one plan marginal ridge increases the depth of adjacent triangular fossa by increasing the stress in this area and also increases the height of the marginal ridge at the centre, and this will deflect the food away from the spillway [Figure 5].
- Thin marginal ridge in mesio-distal bulk:
Will be susceptible to fracture or deformation leading to the problems of previously mentioned faulty marginal ridge (discussed in point 1, 2, 3 and 4) [Figure 6].
Studies have shown that regardless of loading directions and location, the marginal ridges and proximal contact area were sites of low strain.  Thickness of enamel at the marginal ridge is high and loss of tooth structure in this area weakens the tooth structure. Both clinical and experimental studies have highlighted the importance of preserving the marginal ridge. ,,
Effective dentine thickness
The depth of the cavity is most detrimental irritating factor to the pulp. The most important factor is the thickness of the dentine between the floor of the cavity and the floor of the pulp chamber called effective depth. Clinical judgement about the need for specific liners and bases are linked to the amount of the remaining dentine thickness (RDT) which is shown in [Table 4]. 
|Table 4: Pulpal protection depending on the remaining dentine thickness (RDT)|
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Affected and infected dentine
Fusyama has reported two distinct layer of carious dentin, an outer and an inner layer, which is termed as infected dentine and affected dentine. In tooth preparation it is desirable that only infected dentine to be removed leaving the affected dentine. Infected dentine is an outer layer contains micro-organisms and the collagen is irreversibly denatured and it cannot be remineralized, soft in nature, can be stained easily and should be excavated. Affected dentine is an inner layer has no bacteria, reversibly denatured, remineralizable, hard in nature and does not stain and should be preserved. ,
Biological considerations in restorative treatments
Dentine forms the bulk of the tooth and a protective encasement for the pulp. As the vital tissue without vascular supply and innervation it is nevertheless able to respond to thermal, chemical, or tactile external stimuli. Of the various forms of treatment, operative procedures are the most frequent cause of pulpal injury. Trauma to the pulp can't always be avoided, particularly with extensive restorations. A competent clinician, recognizing the hazards associated with each step of the restorative process, can often minimize if not prevent, trauma to preserve the vitality of the tooth. The deleterious affect and its effective management are mentioned in [Table 5].
It's a "V" shaped space that originate from proximal contact,  the interdental space is a physical space between two adjacent teeth, its form and volume are determined by the morphology of the teeth which is composed of cervical, occlusal, buccal and lingual pyramidal embrasures. The apex of the pyramid ends at the contact point of the aproximal teeth. 
The correct relationship of embrasure, cusp to sulci, marginal ridge and grooves of adjacent and opposing teeth provide opportunity for escape of food from the occlusal surface during mastication. 
An exaggerated occlusal embrasure because of faulty marginal ridge will direct force 1 and 2 towards adjacent proximal surfaces with the horizontal component driving the tooth away and the vertical component 1V and 2V pushing the debris into proximally [Figure 7].
Absence of occlusal embrasure because of faulty marginal ridge will act like a pair of tweezers grasping the food. Although debris won't be pushed interproximally it will be very difficult to remove [Figure 8].
Integrity of the dental papilla is the main concern while restoring the tooth. The absence and loss of interdental papilla which intern leads to absences or loss of embrasure may cause aesthetic impairment, phonetic problems, and food impaction.
Biological width and restorations
It's defined as dimension of soft tissue which is attached to the portion of the tooth coronal to the crest of the alveolar bone. The term was based on work of Gargiulo et al.,  it provides the natural seal that develops around the tooth protecting the alveolar bone from the infection and the disease. 
Gargiulo et al., reported that marginal width is commonly about 2.4 mm, which represents the some of epithieal and connective tissue measurements that is sulcus of 0.69 mm, epithelial attachment of 0.97 mm and a connective tissue width of 1.07 mm.  The width is not constant it varies according to the location of the tooth [Figure 9].
Biological width impingement is of concern when considering the restoration of the tooth with a subgingival fracture or has been destroyed by subgingival caries approaching the alveolar crest. Often aesthetic restoration makes sub gingival margins leads the violation of these space. Jorgic- Srdjak K et al., have stated that when sub gingival margins are indicated, the restorative dentist must not disrupt the junctional epithelium or connective tissue apparatus. 
Supragingival margins provides easy preparation of the tooth, finishing of the margins, impression making, fit and finish of the restoration, verification of the restoration, less irritating to the periodontal tissues. 
Traditionally this type of margins were not desirable, as it favors to lot of food accumulation which leads to increased gingival inflammation and also concern was the minor gingival recession would create an unsightly margin display.
These drawbacks are not valid today, not only because margins can be aesthetically blended with the tooth and also the restoration can be finished easily. From the periodontal view both supragingival and equigingival margins are well to be tolerated. 
Restorative consideration will frequently detect the placement of restoration margins beneath the gingival crest; invasion of biological periodontal ligament space for additional retention space will cause iatrogenic periodontal ligament disease with the premature loss of restoration. 
Subgingival restorations have demonstrated more quantative and qualitative changes in micro flora, increased plaque index, gingival index, recession, pocket depth and gingival fluid. ,
Biologic width violation leads to chronic progressive gingival inflammation, Clinical attachment loss and alveolar bone loss. Gingival hyperplasia is also most frequently found in subgingivally placed restorative margins.
Evaluation of biologic width violation
The most important diagnostic method is bone sounding, which is done by probing under local anaesthesia to bone level. Biologic width is assessed by subtracting the sulcular depth from the resulting bone sounding measurement. If this distance is less than 2 mm, then a violation of biologic width can be diagnosed. Radiographic evaluation can assess interproximal violation of biologic width. But it is not diagnostic because of tooth superimposition. 
Evaluation of biologic width
The techniques employed in dental practice for the evaluation of biologic width. 
By Periodontal probe.
Correction of biologic width violation
Biologic width violation can be corrected surgically or orthodontically. 
- Surgical correction is aimed at removing the bone away from the restorative margin done by gingivectomy, apically repositioned flap with or without ostectomy.
- Orthodontic correction, the tooth is moved coronally away from the bone is done either by slow eruption or forced eruption with supracrestal fiberotomy.
Biologic considerations during implant restoration
The ultimate long term success of implants is largely relied upon the interphase between implants and their surrounding tissues, both hard and soft tissues. Dental implant have two distntic interface with oral tissues.
- The soft tissue- implant interface is where the peri-implant mucosa meets the implant creating a biological seal to prevent future disease invasion. Due to the natural of the tissue component, soft tissues surrounding the dental implants are called peri- implant mucosa instead of gingival.
- The hard tissue- implant interface where the alveolar bone contact with implant surface. This integration provides stability and rigidity that implant needs. 
The successful integration of periodontal and restorative dentistry for both natural teeth and implant requires knowledge and application of both biological and mechanical principles.
Subgingival margins should be considered as a compromise and supragingival margins are preferred.
Where the aesthetic is not a concern and adequate tooth structure exists, supra gingival margins are recommended. In areas with the inadequate tooth structure crown lengthening or orthodontic extrusion can be used to increase clinical crown lengthening.
For subgingival placement of the dental implant several principles should be considered.
- The marginal fit should be optimal because of the rough surface or open margin leads to bacterial accumulation that are associated with inflammatory periodontal disease.
- The margins of the implant should extend only slightly into the gingival sulcus, to avoid violation of biologic width.
- Materials used in the restorations should be compatible with the soft tissue and lend themselves to the precise interface to minimize marginal discrepancies that encourages retention of bacterial plaque.
In areas of aesthetic concern, to minimize the effect of bacterial trap at the implant and restorative junction the clinician should consider selection of the implant system that:
- Has the interphase coronal to facial and lingual bone.
- Provides the closest possible implant/abdument interface.
- Allows screw- retained restorations. 
Considerations for complex restorations
An operator should have a through knowledge of restorative design, materials and technique when examining the badly mutilated teeth following steps should be taken before finalizing that design and executing it.
- Evaluate the P-D organ and the periodontium of the tooth to be restored, preferably before the patient is anesthetized.
- Remove all the undermined enamel. There is no place for such enamel in all permanently restored posterior teeth.
- Clean all surrounding walls from dentin that is infected.
- Through knowledge of biologic concept is a must (as discussed above). 
Restorative margin and periodontium
The gingival peripheral destructions should be recorded and the margins of the restorations should be planned accordingly:
- If the tooth destruction is located supragingivally, no need for the any change in the periodontium.
- If the tooth destruction is located apically to gingival cervice but suprabony, gingivectomy is performed to expose the apical limit of defect.
- If apical limit of defect is infrabony:
- Full thickness mucoperiosteal flap is raised with osteotomy to correct the defect.
- Intentional extrusion of the tooth is done.
| Conclusion|| |
The relationship between restoration and periodontal health of the teeth is intimate and inseparable; maintenance of gingival health constitutes one of the keys for tooth and dental restoration longevity. An adequate understanding of relationship between periodontal tissues and restorative dentistry is paramount to ensure adequate form, function and aesthetics and comfort of the dentition.
The clinician should have an adequate knowledge about anatomy and the functional aspects of contacts and contour so as to reproduce using proper restorative material. Recent updates with extensive knowledge about the matrix system will help to reproduce the normal anatomy and contacts between the teeth which will help in maintaining the healthy oral cavity.
In spite of the increase emphasis on the perio-restorative interphase in restorative dentistry, many dentists have been unable to utilize the concept of biological width in a practical manner, so this article is briefed about the clinical considerations during restoration.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]