Knowledge, Awareness and Practice on Cantilever Abutment among Dental Students and Practitioners – A Survey

 

Nur Liyana Hannah Binti Izham Akmal¹, Dr. Ashish R Jain²

¹Department of Prosthodontics, Saveetha Dental College, Saveetha University 162, Poonamallee High Road, Chennai 600077 Tamil Nadu, India

²Graduate Student, Saveetha Dental College, Saveetha University, Chennai, India

 

ABSTRACT:

Background: Cantilever abutment is part of a prosthesis which supports the artificial tooth only on one side, which is commonly used for the replacement of maxillary lateral incisor with central incisor or canine as the abutment and full mouth rehabilitation in which there is no abutment in the posterior region. Cantilever abutments are usually preferred for aesthetic purposes, in the absence of teeth on one side of the breach and when one of the abutment teeth is used to support another prosthesis which cannot be replaced. Aim: To evaluate cantilever abutment in prosthodontics and its effects on prosthesis and to study the use of cantilever abutment in prosthesis and its contributions to the replacement of individual’s teeth. Materials and Method: A questionnaire-based study was done among dental students and practitioners. A total of 100 participants took part in the survey. All the participants were provided with a list of 11 questions related to their understanding about cantilever abutment. Data was collected and statistic analysis was done. Results: Posterior cantilever abutment is more preferred than anterior cantilever abutment (69%). Chewing pressure is the main factor for abutment selection (64%). Posterior cantilever abutment is used when one of the abutment teeth is already supporting another prosthesis and cannot be replaced due to various reasons (47%). Two abutments are used for replacing a mandibular molar (71%). Lower second premolar and lower first molar are preferred to replace lower first premolar (52%). Secondary abutment reduces occlusal forces (38%) as abutment helps to transmit extra pressures (70%). Loss of occlusal stability is a common complication of cantilever abutment (57%). Less chewing pressure is the main benefit of anterior abutment (47%). The success of cantilever abutment is moderate (50%). Patients can tolerate unilateral occlusal scheme better (50%). Conclusion: Cantilever abutment is considered as a great alternative for the replacement of a single tooth. Further studies need to be done in order to develop better understanding and appropriate solution to overcome the problems associated with cantilever abutment.

 

 

 

 

INTRODUCTION:

Every restoration should have the ability to withstand the constant occlusal forces to which it is subjected in the oral cavity.^[1] Following the replacement of a missing tooth, forces that would normally be absorbed by the missing tooth are transmitted to the abutment teeth through the pontic, connector and retainer, which are parts of prosthesis. Abutment refers to a tooth, a portion of the tooth or a portion of an implant used for the purpose of supporting a fixed or removable prosthesis.^[2]Abutments are primarily used to bear the forces that are initially directed to the missing teeth, in addition to those which are applied directly to them and transmit the forces to the underlying periodontium.^[3]

Various factors should be considered in selecting a suitable abutment which include the vitality of tooth, adequate crown root ratio, sufficient thickness of enamel and dentin, sufficient bone support, absence of periodontal disease and appropriate gingival contour.^[4] Abutments that are selected based on their ideal requirements, along with prompt diagnosis and meticulous treatment planning can provide better retention and stability to the prosthesis. Thus, it is very important for dentists to understand the basic concepts of an abutment in order to make the appropriate choice and ensure the success of the final restoration and better prognosis of the treatment.

 

 

Figure 1: Cantilever Abutment, P-Pontic, A-Abutment

 

Cantilever abutment is part of a prosthesis which supports the artificial tooth only at one end, while the other end of the pontic remains unsupported.^[2] It is commonly indicated in the anterior region of the mouth for the replacement of maxillary lateral incisors using canine as the abutments.^[5] Cantilever abutment can also be used to replace a mandibular first molar with both premolars as the abutments and the pontic is often the size of the premolars in order to reduce the stress applied on the abutments.^[6] Restoration of teeth in the posterior region of the mouth normally requires a secondary abutment to avoid excessive vertical forces which can cause tipping and eventually loss of stability and support. For example, in the replacement of first premolar where second premolar and first molar act as the abutment.^[5]In a cantilever fixed partial dentures, at least two teeth should be used as abutments in order to replace a single tooth and there should be no occlusal contact on the pontic (Table I).

 

 

Table I: Types of abutment and their features

 

Table II: Factors affecting abutment selection with description

S. No.	Factors affecting Abutment Selection	Description
1.	Crown Form	Additional forces may result from good morphology of the adjacent teeth or pontics The forces can be uniformly distributed by the presence of additional abutments.
2.	Crown Length	Pontics with increased occlusogingival height require additional abutment. Abutment teeth with less than 4mm crown can be supported by splinting multiple abutment.
3.	Crown Root Ratio	The optimum ratio is 2:3 and the least accepted is 1:1 Root support should be more than the crown height
4.	Ante’s Law (Periodontal Surface Area)	Introduced by Irwin H. Ante (1926) and later by Johnston (1971) “The combined pericemental area of the abutment teeth should be equal to or greater in pericemental area than the teeth to be replaced”. Additional abutments are required if the pericemental area of the abutment teeth is less.
5.	Axial Alignment	The alignment of the long axis of the abutment teeth to each other. A tilt up to 25 degrees for full veneer preparation and 15 degrees for resin bonded bridges.
6.	Arch Form	Pontics lying outside the interabutment axis line can act as a lever arm which produces a torqueing movement. Secondary retention extends from the primary interabutment axis, which is similar to the distance extended by the pontic lever arm in the opposite direction.
7.	Alveolar Ridge Form	Ideally, the ridge should be flat and wide Excessive resorption can lead to low and thin ridges, along with high pontics and increased torsional forces.
8.	Root Form and Length	Teeth with longer roots like canine are more preferable Labiolingually conical root is more stable than circular Apical divergence provides better support than apical convergence.
9.	Occlusion	Based on the scheme of occlusion such as a single abutment for mutually protected occlusion.
10.	Span Length	Relative deflection, either directly proportional or inversely proportional. Long span prosthesis provides greater flexion.
11.	Esthetics	Full coverage crown provide better esthetics and retention. Anterior abutments with long connectors also provide good esthetics.
12.	Periodontal Health	Insufficient periodontal health can result in poor prognosis. Periodontally compromised tooth should not be considered as an abutment.
13.	Pulpal Health	Vital teeth are often preferable due to better proprioception. Inadequate pulpal heath can lead to poor prognosis. Necessary treatment may be required prior to restoration such as prophylactic root canal therapy.
14.	Psychology	Mentally compromised patients may require multiple splintered abutments. Splinted abutments helps to distribute para functional forces.
15.	Phonetics	Abutment should not be bulky as it may affect the patient’s phonetics.
16.	Prognosis	A prosthesis should last for at least 60% of the time in the span of 20 years.
17.	Mutilation	Sufficient abutment height of at least 4mm should be present. Core build up with composite resins can be done for tooth lesser than 4mm occlusogingivally.
18.	Mobility	Teeth with grade 1 mobility can be splinted with additional abutments while teeth with grade 2 mobility are contraindicated. Strong periodontal support can provide better support and stability.

 

Cantilever bridges are often used to replace only a single tooth due to the large amount of forces they applied on the abutment and connector. Forces directed through the cantilevered pontics can result in tilting and rotational movements of the abutments. Hence, it is always ideal to increase the number of abutments and reduce the number of pontic in order to ensure better prognosis of the restoration.^[7] Abutment selection should also consider its size, being at least the same size or larger than the pontic and occlusal arrangement to prevent massive load acting on the pontic^[5](Table II).

 

Sufficient bone support, adequate tooth structure for increased retention of final retainer, development of an ideal occlusal scheme, good crown-tooth ratio and healthy periodontium are parts of the ideal requisites for cantilever abutment.^[2] Cantilever abutment are indicated for the replacement of lateral incisor with canine support, first premolar with second premolar and first molar support and first molar with first and second premolars support.^{[3, 5]} It is contraindicated in the presence of endodontically treated teeth especially with excessive crown damage, teeth with short roots and teeth with active periodontal problem.^[1] Advantages of cantilever abutment include conservation of tooth structure, reduced time of preparation, improved aesthetics and less costs while the disadvantages consists of fractured tooth and loosened crown

 

Cantilever abutment is considered as a great alternative for the replacement of a single tooth, especially in the anterior region of the mouth. Hence, this study aims to evaluate cantilever abutment in prosthodontics along with its effects on prosthesis and contributions to the replacement of individual’s teeth.

 

MATERIALS AND METHODS:

A questionnaire-based study was done among dental students and practitioners. A total of 100 participantstook part in the survey. All the participants were provided with a list of 11 questions related to their understanding about cantilever abutment with answers given for each question. Ideally, the sample size of the survey was calculated to be 132, which indicates 100 participants are sufficient for this study (Figure 2).^[20]The participants were told to choose only one answer based on their personal opinion (Table III).

 

Sample Size for Frequency in a Population
Population size (for finite population correction factor or fpc)(N): 200 Hypothesized % frequency of outcome factor in the population (p): 50%+/-5 Confidence limits as % of 100(absolute +/-%)(d): 5% Design effect (for cluster surveys-DEFF): 1
Sample Size(n) for various Confidence Levels
Confidence level (%)	Sample size
95% 80% 90% 97% 99% 99.9% 99.99%	132 91 116 141 154 169 177
Equation
Sample size n = [DEFF*Np(1-P)]/[d2/Z21-α*(N-1)+p*(1-p)] Results from OpenEpi, Version 3, open source calculator--SSPropor Print from the browser with ctrl-P or select text to copy and paste to other programs.

Figure 2: Sample size calculation^[20]

 

Table III: List of survey questions on cantilever abutment with answers

 

RESULTS:

A questionnaire-based study was done among dental students and practitioners. A total of 100 participants took part in the survey. All the participants were provided with a list of 11 questions related to their understanding about cantilever abutment with answers given for each question. Data was collected and statistic analysis was done using Microsoft excel.

 

 

It can be seen that most of the participants prefer posterior cantilever abutment for the replacement of a missing upper first premolar as 69% of them selected the same answer for Question 1 of the survey, while the remaining 31% of them recommend anterior cantilever abutment for replacing the upper first premolar (Figure 3).

 

Given a condition of a missing upper first premolar which abutment do you thin is the most suitable for the patient?”

 

Figure 3:Most suitable abutment for missing upper first premolar

 

The result in shows that 64% of the total participants agree that chewing pressure is the main factor being considered in the selection of an anterior or posterior cantilever abutment and the remaining 36% of them chose esthetic factor as the most important component in the selection of an abutment (Figure 4).

 

“What Factor do you consider the most in the selection of an anterior or posterior cantilever abutment”

 

Figure 4: Factor to consider the most in the selection of an anterior or posterior cantilever abutment

 

It can be seen that most of the participants are aware of the various conditions in which cantilever abutment can be indicated. Approximately 47% of the participants recommend posterior cantilever abutment when one of the abutment teeth is already supporting another prosthesis and cannot be replaced due to various reasons. While in conditions where it is not desirable to prepare a tooth in the visible part due to esthetic reason, about 36% of them would consider a posterior cantilever abutment. The remaining 17% of the participants state that posterior cantilever abutment should be indicated when a temporary restoration is required (Figure 5).

 

“In which condition, do you think a posterior cantilever abutment is mormally indicated”

 

Figure 5: Condition in which posterior cantilever is mainly indicated

 

 

Most of the participants (71%) would consider 2 abutments in the replacement of a missing mandibular molar, which is indeed preferable by many practitioners due to its high strength and support. While 26% of the participants still prefer having 1 abutment, which can be due to the conservation of the tooth structure and the remaining 3% of them had chosen more than 2 abutments for replacing a missing mandibular molar (Figure 6).

 

“Ideally, how many abutment teeth are required to replace missing mandibular molar”

 

Figure 6: Number of abutment teeth required to replace a missing mandibular molar

 

In the abutment selection for replacing a missing lower first premolar,slightly more than half of the participants (52%) had chosen lower second premolar and lower first molar (Posterior) as the abutments, while 21% of them prefer anterior cantilever abutments by choosing lower second premolar and lower canine as the abutments. Some of the participants suggest that only 1 abutment would be sufficient to replace a lower first premolar as 13% of them chose lower second premolar, 9% of them with lower first molar and 5% of the participants selected lower canine asthe abutments (Figure 7).

 

“In the replacement of a missing lower first premolar, which teeth would you consider as the abutment?”

 

Figure 7: Teeth to be considered for missing lower first premolar

In order to overcome the problems of occlusal forces acting on an abutment tooth, 38% of the participants suggest the use of a secondary abutment to transmit the forces, while 25% of them recommend a same size or larger abutment compared to the pontic to overcome the forces. The use of anterior abutment due to less biting force compared to that of the posterior and incorporation of grooves on the buccal and lingual surfaces of the tooth may help in reducing the occlusal forces as preferred by 22% and 14% of the participants respectively. The remaining 1% of them prefers other methods of reducing the occlusal forces acting on the abutment tooth (Figure 8).

 

 

How do you overcome the occlusal forces acting on an abutment tooth

 

Figure 8: Method to overcome the occlusal forces acting on an abutment tooth

 

Since the number of abutment plays an important role in the placement of a prosthesis, the result indicates that 70% of the participants suggest that appropriate number of abutment may help in the distribution of additional pressures acting on the abutment teeth and 30% of them agree that proper number of abutment helps in conservation of the tooth structure (Figure 9).

 

 

 

Why do you have to consider the number of aubment prior to a restoration with cantilever aubment

 

Figure 9: Importance ofthe number of abutment

 

It can be seen that the most of the participants have a good level of understanding on cantilever abutment as 57% of them are aware of the loss of occlusal stability due to tipping forces seen commonly as a complication of cantilever abutment. 13% of them associate cantilever abutment with orthodontic movement of the teeth, 11% with fractured tooth and 10% of them suggest loosened crown as the common complications of cantilever abutment. Short lifespan and prognosis are also considered as a common complication of cantilever abutment by 9% of the participants (Figure 10).

 

 

 

What is the Common complication of a cantilever abutment

 

Figure 10: Common complication of a cantilever abutment

The resultreveals that 47% of the participants selected “less chewing pressure acting on the abutment” as the main advantage of an anterior cantilever abutment. Good esthetics and conservation of tooth structure are also another main advantages of anterior cantilever abutment as chosen by 26% and 24% of the participants respectively. The remaining small group of 4% of the participants suggests low cost as the main benefit of anterior cantilever abutment (Figure 11).

 

 “What is the Main advantage of an anterior cantilever abutment

 

Figure 11: Main advantage of an anterior cantilever abutment

 

It can be seen that half of the total participants (50%) believe that the success rate of prosthesis with cantilever abutment is only moderate. 44% of the participants suggest high rate of success for restoration using cantilever abutment while 4% of them rate it as low and only 2% of them suggest that the success of prosthesis with cantilever abutment as “very high” (Figure 12).

 

“How would you rate the success ot prosthesis with cantilever abutment

 

Figure 12: Success rate of cantilever abutment

 

Most of the participants suggest “unilateral” as the best occlusal scheme for cantilever abutment, accounting for about 50% of the total participants. 35% of the participants believe that bilateral cantilever abutment is better tolerable by the patients and the remaining 15% of them suggest full arch cantilever abutment as the favorable occlusal scheme for cantilever abutment (Figure 13).

 

 

“Which occlusal scheme for cantilever abutment is better tolerable?”

 

Figure 13: Most tolerable occlusal scheme for cantilever abutment

 

DISCUSSION:

This study was done as a questionnaire-based survey among 100 dental students and practitioners in Chennai city. Cantilever abutment forms part of a prosthesis that supports the artificial tooth only at one end, while the other end of the pontic remains unsupported. It is usually indicated in the anterior region of the mouth for the replacement of maxillary lateral incisors using canine as the abutments.^[5] Although, it is less commonly indicated due to the large amount of forces it applies on the other structures, cantilever abutment is still preferred by most dental practitioners especially in the replacement of a single tooth.

 

Based on the result, 69% of the participants would prefer posterior cantilever abutment for the replacement of a missing upper first premolar and the remaining 31% had chosen anterior cantilever abutment for this condition. This is most probably due to the basic idea that the posterior tooth can provide better support and retention for the artificial tooth that replaces the missing teeth.⁸Based on a study by Cheung and his colleagues, approximately 67% of his patients were contraindicated withthe placement of anterior abutment to replace missing upper canines due to the presence of fractured porcelain or abutment tooth.^[22]

 

According to 64% of the participants, chewing pressure is an important factor to be considered the most before selecting an anterior or posterior cantilever abutment, while the other 36% of them disagree by indicating that esthetic factor is the most important component during abutment selection. Although both factors are considered important in the selection of an appropriate abutment, it is always better to pay extra attention on the patient’s chewing pressure as it may impose additional tension on the tooth structures.^[9,10]However, a study by Nyman (1979) stated that the additional stress acting on the abutment teeth is often readily adapted and usually the presence of an additional pontic also indicates the incorporation of an additional abutment in cases of non-mobile teeth.^[17]

 

It can be seen that there are various conditions in which posterior cantilever abutment can be indicated such as when one of the abutment teeth is already supporting another prosthesis and cannot be replaced due to various reasons as chosen by 47% of the participants. 36% of them would consider a posterior cantilever abutment in conditions where it is not desirable to prepare a tooth in the visible part due to esthetic reason and 17% of the participants suggest that posterior cantilever abutment is the most suitable when a temporary restoration is required compared to other types of abutment.^[3]

 

71% of the participants had chosen 2 abutments as the most appropriate for the replacement of a missing mandibular molar, which is indeed preferable by many practitioners due to its high strength and support.^[5] In order to ensure the conservation of the tooth structure, 26% of the participants suggest that only 1 abutment is sufficient to replace a mandibular molar. The remaining 3% of the participants would consider more than 2 abutments for this condition, which is the least preferable by most practitioners.

 

Cantilever abutment should only be used for the replacement of single tooth as it may impose a large amount of forces on both the abutment and connector.^[11]In the replacement of a missing lower first premolar, 52% of the participants would consider lower second premolar and lower first molar as the abutments, while 21% of them prefer lower second premolar and lower canine as the abutments.Although it has been reported previously that the use of double abutments are usually contraindicated in most cases due to leakage and caries resulting from the uneven distribution of pressure and fracture of the cement lute of the weakest retainer, the use of second premolar and first molar are still preferred for the replacement of a missing first premolar especially when the occlusal loads are high.^[5,12]

 

In order to overcome the occlusal forces especially when cantilevering a pontic in the posterior region of the mouth, 38% of the participants suggest a secondary abutment, which is indeed the best option as it reduces the additional vertical forces that may result in loss of stability caused by tipping.^[5] According to Tjan (1981), incorporation of buccal and lingual grooves on the tooth surface as selected by 14% of the participants is also another preferable method of reducing occlusal pressure.^[13] 22% of them prefer the use of anterior abutment due to lesser biting force than that of the posterior but a report by Schwarts (1970) stated that in cases of splinted abutments, single posterior cantilever is usually preferred as an alternative due to excessive stress by the cement lutes.^[14]The remaining 25% of the participants would recommend a same size or larger abutment compared to the pontic, which is also considered as a great alternative to overcome the forces.^[8]

              

Aside from the arrangement of occlusion and the requirement for abutment being at least the same size or larger than the pontic, the success of a prosthesis is also dependent on the number of abutment as 70% of the participantsimplies that the appropriate number of abutment may help in the distribution of additional pressures acting on the abutment teeth and 30% of them agree that proper number of abutment helps in conservation of the tooth structure.^[5]

              

Various complications can be observed when cantilevering a pontic especially in the posterior region of the mouth due to excessive vertical pressure that can cause tipping and eventually loss of occlusal stability as the common complication stated by 57% of the participants.^[15]13% of them agree that tipping forces are also responsible for the orthodontic movement of the teeth.^[5]Since cantilever abutments can exert large amount of forces, 11% of the participants relate them with fractured tooth while 10% of them suggest loosened crown as the common implication of cantilever abutment.^[3]By comparison, 5% loosened crown and 3% fractured rootwere previously reported in various studies such as a study by Roberts DH.^[15] The remaining 9% of the participants indicate short lifespan and prognosis as the main problem with this type of abutment, which explains why dental implants are always preferable in most conditions.

 

A report by Lundgren and Laurell (1986) stated that the biting force acting on the anterior region is lesser than the posterior biting force that further reduces the pressure on anterior cantilever loading, which suggests a significant advantage of an anterior cantilever abutment as indicated by 47% of the participants.^[7] Although “good esthetics” is also considered as a primary advantage of anterior cantilever abutment by 26% of them, dentists usually prefer a three-quarter crown or adhesive wing with preparation as most patients show low esthetic demands.The other benefits such as conservation of tooth structure and low cost chosen by 24% and 4% of the participants respectively are commonly associated with two-unit cantilever bridge, in which one pontic is retained by one abutment tooth.^[12]

 

The success rate of a cantilever abutment is considered to be moderate by 50% of the participants, especially in the presence of a root-filled end abutment which should be removed, leading to a decreased number of abutment compared to the pontic.^[16]By comparison, a study by Owall (1971) indicates a slightly higher success rate of 75% with cantilever abutment as distal tipping occurs with time.^[12]44% of them believe that there is a high rate of success for any restoration with cantilever abutment. While the remaining small group of participants rate the success of cantilever abutment as “low” and “very high” with each 4% and 2% respectively.^[18]

 

Proper occlusal scheme plays an important role in the selection of a suitable abutment. The result shows that 50% of the total participants suggest that unilateral cantilever abutment is better tolerable by most patients.^[19] However, 35% of them disagree with the idea by stating that bilateral cantilever abutment is the most acceptable for the patients and the remaining 15% of them believe that patients can best endure full arch cantilever abutment. In the presence of a proper occlusal scheme, cantilevering a lateral incisor from a central incisor, or central incisor from another central incisor becomes a simple restorative procedure, which benefits both the patients and dentist.^[5]

 

CONCLUSION:

Cantilever abutment is considered as agreat alternative for the replacement of a single tooth, especially in the anterior region of the mouth.It has been reported previously thatthe demand for cantilever abutment by dentists during preparation of the tooth and occlusal adaptation has increased steadily throughout the years, which can be mainly attributed to its indications in numerous conditions such as in the absence of teeth on one side of a breach and when esthetic demand is concerned, along with its advantages that include the conservation of tooth structure.

 

Despite the need for cantilever abutment, there is a rising concern in the use of this type of restoration as cantilever abutment is commonly associated with various complications, which may adversely affect both the patient and dentist such as short lifespan and prognosis of these restorations. Therefore, these solutions are rarely preferred by most dentists nowadays especially with the development of dental implants that are more favorable in various treatments. Further studies need to be done in order to develop better understanding and appropriate solution to overcome the problems associated with cantilever abutment.

 

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2.       Veeraiyan DN. Textbook of prosthodontics. 2^nd edi. New Delhi: Jaypee Brothers; 2017, p.727

3.       Am R, Sa A, Ps L, Js R, Te S. Evaluation of strain at the terminal abutment site of a fixed mandibular implant prosthesis during cantilever loading. Implant Dentistry. 1994;3(1):56.

4.       Raja DR, Nesappan T. Management of Narrow Edentulous Space of Two Missing Teeth in Maxillary Aesthetic Zone Using Implant as Abutment with a Cantilevered Tooth - a Case Report. International Journal of Dental Sciences and Research. 2014;2(4):76–9.

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7.       Laurell L, Lundgren D. Influence of occlusion on posterior cantilevers. The Journal of Prosthetic Dentistry 1992;67:645–52.

8.       Burgess JO, Mccartney JG. Anterior retainer design for resin-bonded acid-etched fixed partial dentures. The Journal of Prosthetic Dentistry 1989;61:433–6.

9.       Lundgren D, Laurell L. Occlusal force pattern during chewing and biting in dentitions restored with fixed bridges of cross-arch extension. Journal of Oral Rehabilitation 1986;13:57–71.

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11.     Standlee J, Collard E, Caputo A. The Journal of Prosthetic Dentistry. The Journal of Prosthetic Dentistry 1971;25:101–2.

12.     Owall B et al Two-unit cantilevered fixed partial dentures. Dental Abstracts 2014;59.

13.     Tjan A and Miller GD The role of an axial groove in enhancing the resistance of a crown and fixed partial denture. Quintenssence iNT 1981;5:489

14.     Schwartz NL, Whitsett L, Berry TG, Stewart JL. Unserviceable Crowns and Fixed Partial Dentures: Life-Span and Causes for Loss of Serviceability. The Journal of the American Dental Association 1970;81:1395–401.

15.     Roberts DH. The failure of retainers in bridge prostheses. An analysis of 2, 000 retainers. British Dental Journal 1970;128:117–24.

16.     Lundgren D. Prosthetic reconstruction of dentitions seriously compromised by periodontal disease. Journal of Clinical Periodontology 1991;18:390–5.

17.     Nyman S, Lindhe J. A Longitudinal Study of Combined Periodontal and Prosthetic Treatment of Patients With Advanced Periodontal Disease. Journal of Periodontology 1979;50:163–9.

18.     Wright WE. Success with the cantilever fixed partial denture. The Journal of Prosthetic Dentistry 1986;55:537–9.

19.     Abichandani S, Kavlekar A, Nadiger R. Abutment selection, designing, and its influence on the emergence profile: A comprehensive review. European Journal of Prosthodontics 2013;1:1.

20.     Irimia R, Gottschling M. Taxonomic revision of Rochefortia Sw. (Ehretiaceae, Boraginales). Biodiversity Data Journal 2016;4:7720.

21.     Jo L, Vamsi K, Ariga P, Bholla P. Influence of occlusal loading on stress patterns at the bone-implant interface by angulated abutments in the anterior maxilla: A three-dimensional finite-element study. Journal of Dental Implants 2014;4:3.

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Accepted on 30.04.2018           © RJPT All right reserved

Research J. Pharm. and Tech 2018; 11(7): 3067-3076.