SRM Journal of Research in Dental Sciences

: 2021  |  Volume : 12  |  Issue : 4  |  Page : 186--191

A cross-sectional study on the assessment of the complexity of removable dental prosthesis at a tertiary hospital in Nigeria

Julie Omole Omo, Joan Emien Enabulele 
 Department of Restorative Dentistry, University of Benin, Benin, Nigeria

Correspondence Address:
Dr. Julie Omole Omo
Department of Restorative Dentistry, University of Benin, Benin


Background: Oral rehabilitation using removable dental prosthesis for patients with maxillofacial defects and missing teeth could pose a challenge while trying to achieve prosthetic treatment goals. It is important therefore to determine how complex the case is before proceeding with treatment. Aim: The aim of the study was to assess the complexity of removable dental prosthesis at a tertiary hospital in Nigeria using the Restorative Index of Treatment Need (RIOTN) System. Materials and Methods: This was a descriptive cross-sectional study of patients who sought for removable prostheses. Data were collated by means of an interviewer-administered question which collated data on biodemographic characteristics of the participant, indication for removable prosthesis, tooth to be replaced with removable prosthesis. Following a clinical examination, the RIOTN System was applied to assess the complexity of the treatment needed. Results: Ninety-eight adult patients with age ranging from 18 years to 90 years with a mean age of 45.17 ± 18.06 years participated in the study. Partial dentures were the most prevalent prostheses provided (91.8%). The most prevalent complexity grade recorded was Grade I (84.7%). There was a statistically significant association between complexity and Kennedy's class of saddle (P < 0.0001) as well as the type of support for the removable prosthesis (P < 0.0001). Conclusion: The pattern of the complexity of treatment using removable dental prostheses was dependent on the type of prosthesis, teeth replaced, support, and saddle.

How to cite this article:
Omo JO, Enabulele JE. A cross-sectional study on the assessment of the complexity of removable dental prosthesis at a tertiary hospital in Nigeria.SRM J Res Dent Sci 2021;12:186-191

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Omo JO, Enabulele JE. A cross-sectional study on the assessment of the complexity of removable dental prosthesis at a tertiary hospital in Nigeria. SRM J Res Dent Sci [serial online] 2021 [cited 2022 May 17 ];12:186-191
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Loss of teeth and associated structures lead to loss of function and probably a reduced quality of life of the subjects involved. The replacement of missing teeth and associated structures is needed to improve appearance, enhance masticatory efficiency, prevent overeruption/drifting of teeth, and/or improve phonetics.[1] This loss could be rehabilitated by various forms of prostheses which include both removable and fixed prostheses. The removable dental prostheses comprise removable partial denture, complete dentures, various types of maxillofacial prostheses, and implant-supported prostheses.

The complexity associated with treatment using removable dental prostheses ranges from simple single tooth replacement to replacement of teeth and associated maxillofacial structures that probably would have been removed by surgery or trauma. The management of orofacial tumors may lead to facial deformities that affect basic functions such as feeding, speech, and the reduction of patient self-worth.[2] The complexity is compounded by the type of support, retention, and challenges associated with them.

Prosthodontic treatment cases range from simpler cases to more challenging cases with the possibility of reducing complex treatment to simpler components with careful planning.[3] Designing a removable prosthesis has been shown to be characterized by multifaceted design problem which is open ended and ill structured.[4] It is important that the complexity of prosthodontic cases be determined before the commencement of treatment planning to enable identification of the best option to be applied. Furthermore, the provision of prosthodontic treatment has been demonstrated to be complicated by systemic conditions and long-term use of certain medications.[5] It will be of great benefit when managing prosthodontic patients to predict the difficulties and challenges one may encounter to help overcome such challenges that were envisaged. The ability to predict treatment outcome is very critical to making a choice whether to treat if within a clinician's proficiency or not to treat but to refer to a specialist prosthodontist. Furthermore, there appears to be dearth of literature assessing the complexity of removable dental prostheses, and the result of this study will contribute to the body of existing literature. Hence, the essence of this study was to assess the complexity associated with the provision of removable dental prosthesis in a tertiary institution in Nigeria.

 Materials and Methods

Study design

This was a descriptive cross-sectional study.

Study setting

This study was done in the Prosthodontics unit of the Department of Restorative Dentistry, University of Benin Teaching Hospital between August 2018 and July 2019. The study was approved by the University of Benin Teaching hospital ethical committee in July 2018 with reference number ADM/E22/A/VOL. VII/1404 before the commencement of the study. All the participants provided written informed consent for participation in the study. All procedures performed in the study were conducted in accordance with the ethical standards given in 1964 Declaration of Helsinki, as revised in 2013.

Study participants

Patients who were partially dentate and/or with maxillomandibular defects who sought oral rehabilitation using removable dental prostheses.

Inclusion criteria

All partially dentate individual, patients with maxillary defects, and patients with mandibular defects who have never used a prosthesis.

Exclusion criteria

All completely edentulous patients.

Sampling technique

A convenience sampling technique was employed to recruit the total population of patients who presented for oral rehabilitation by means of removable dental prosthesis.

Study size

The minimum sample size (n) was calculated using the formula by Charan and Biswis for a descriptive cross-sectional study.[6] To account for nonresponse, the formula for nonresponse adjustment was used giving the final minimum sample size of 92 with prevalence from a previous study.[7]

Data collection

Data were collected by means of an interviewer-administered questionnaire. The first section consisted of sociodemographic characteristics of the participant (age, gender, and level of education); the second section consisted of history of the missing tooth/defect; the third section consisted of clinical examination to determine the tooth to be replaced with a removable prosthesis, Kennedy's classification of the saddle area and type of support for the removable prosthesis.

Following clinical examination, the complexity of treatment problem was determined using the removable prosthodontics treatment assessment component of the Restorative Index of Treatment Need System.[8] A complexity code was assigned based on this assessment. The removable prosthodontics treatment complexity assessment is made up of three grades (low – 1: Moderate – 2: and High – 3)[8] to which a modifying factor can be applied, with a modifying factor increasing a complexity score by one code increment and not cumulative. After application of a modifying factor, the final complexity grade was obtained.

Statistical methods

All data collated were screened for completeness and analyzed using IBM SPSS version 26.0 (Armonk, NY: IBM Corp) statistical software. The statistical tools used for the data analysis were descriptive statistics (frequency counts, percentages, and cross-tabulations). Quantitative variables were presented as means and standard deviation. Associations between categorical variables were tested using Chi-square test and where cells with counts <5 accounted for over 20.0% of the total cells, Fisher's exact test was used with P set at 0.05.


Ninety-eight adult patients with age ranging from 18 years to 90 years with a mean age of 45.17 ± 18.06 years participated in the study. The age group most represented was the 31–50-year-olds accounting for 46.9% of the study population. There was equal representation by gender. Most (58.2%) of the respondents had a tertiary education and 30.6% had secondary education [Table 1].{Table 1}

Partial dentures were the most prevalent prostheses provided (91.8%); this was followed by obturators and mandibular prosthesis that accounted for 6.1% and 2.0%, respectively. The most prevalent tooth group that received prosthesis among the participants were anterior teeth accounting for 69 (70.4%) of the prosthesis, followed by a mixture of anterior and posterior teeth accounting for 21 (21.4%), while posterior teeth only were 8 (8.2%). Kennedy's class III edentulous saddle was the most prevalent saddle recorded, accounting for 66.3% while 22.4% had Kennedy's class IV edentulous saddle [Figure 1].{Figure 1}

The most prevalent prosthesis support noted among the participants was tooth support accounting for 88 (89.8%), mucosa support was 2 (2%), and tooth and mucosa support was 8 (8.2%).The most prevalent complexity grade recorded was Grade 1 (84.7%), followed by Grade 2 and Grade 3 representing 7.1% and 8.2%, respectively [Figure 2]. Majority (82.7%) of the participants required prosthesis replacing anterior teeth where there are acceptable sound or restored teeth to provide anterior guidance. The presence of orofacial defects requiring obturator/restoration was observed in 8.2% of the participants, while 14.3% required prostheses with bounded saddles replacing posterior teeth [Table 2].{Figure 2}{Table 2}

The majority 83 (92.2%) of participants who received partial dentures were graded complexity 1 and 7 (7.8%) were graded complexity 2, while all those who received obturators and mandibular prostheses were graded complexity 3 accounting for 6 (100.0%) and 2 (100.0%), respectively, and this was statistically significant (P < 0.0001). [Table 3] shows the majority (94.2%) of participants who needed a replacement for anterior teeth were graded complexity 1, while less than half (47.6%) of those requiring replacement of posterior teeth were graded complexity 1 and 38.1% of those requiring replacement of both anterior and posterior teeth graded complexity 3, and this was statistically significant (P < 0.0001).{Table 3}

There was a statistically significant association between complexity and Kennedy's class of saddle (P < 0.0001) as well as type of support for the removable prosthesis (P < 0.0001). A higher proportion (85.7%) of Kennedy's class II saddle area was graded was graded as complexity 3, and 93.8% and 90.9% of Kennedy's Class III and IV, respectively, graded as complexity 1. All mucosa-supported prostheses were graded as complexity 3 and 75.0% of those with combined tooth and mucosa support graded complexity 3. The majority (94.3%) of tooth supported prostheses was graded complexity 1 [Table 4].{Table 4}


Removable dental prostheses are a viable option for the rehabilitation of various forms of edentulism and maxillofacial defects with various level of complexity in their management. When challenges are envisioned, it makes management of difficult cases easier with better treatment outcome.

Most of the participants had tertiary education, this may not be unrelated to their level of awareness on the need and benefits of rehabilitation, and the level of education has been correlated to oral health knowledge,[9] hence the positive attitude to oral rehabilitation by the participants.

Removable partial dentures were the most prevalent prostheses provided for the participants. This observation corroborates with that of other studies.[10],[11] This could be credited to the reduced cost and ease of fabrication when compared with other forms of restoration/rehabilitation, especially in a developing economy with financial constraints.

It was observed that the anterior teeth were the most prevalent teeth to receive prosthesis. They play a significant part in esthetics and smile of an individual and tend to boost self-esteem. For anterior teeth, the shape, size, and color are vital for re-establishing esthetics and should be considered during rehabilitation.[12] This observation compares with that of a study;[13] it however differs from that of Jayasinghe et al. were posterior teeth were mostly replaced.[14] The anterior tooth/teeth, when not replaced after loss is obviously visible and unappealing, hence its prompt restoration as evident in this study. Furthermore, when there are posterior teeth missing in addition to the missing anterior tooth/teeth, they are likely to be restored as well.

The Kennedy's class III saddle was the most prevalent saddle area observed in this study. This was the disposition in previous studies,[15],[16] it however differs from that of a study where Kennedy class I and II were the most prevalent saddle areas.[14] This could be because Kennedy's class III saddle being an anterior saddle, when restored it readily improves aesthetics, self-confidence, and well-being. They are readily rehabilitated to avoid embarrassment and indignity.

Support is the resistance to the movement of the denture towards the edentulous ridge.[17] The support for a removable partial denture can either be tooth borne, tooth and mucosa borne, or mucosa borne. Recently, implants have been used as a means of support for removable dental prostheses where they play a protective role in the preservation of the remaining natural teeth and the alveolar bone, especially around the implant.[18] Biomechanically, the support warrants the delivery of forces against the abutment teeth enabling the provision of support and stability to the prosthesis.[19] Occlusal rest acts as a channel of distribution of occlusal forces to the abutment teeth through the rest seat in tooth-supported removable partial denture.[20] In this study, the tooth-supported removable partial denture was prevalent among the prostheses provided for the participants. The extent and direction of movement of removable partial dentures during its functions are influenced by the nature of the supporting structures.[21] Mucosa-supported denture tends to cause more inflammation because of the mechanical pressure on the mucosa tissue adjacent to the abutments and underneath the saddle; this makes the tooth support more significant for gingival health[22] and the preferred type of support.

The complexity assessment is a vital component of the index of treatment need used to assess the complexity of treatment problem following clinical examination.[8] The prognostic value of patient characteristics is masked by the amount of treatment received by the patient, such that patients with complex problems receive more treatment, and the outcome is same with patients with less complex treatment.[23] The treatment process is an extension of the clinician's decision based on knowledge and clinical experience, and this affects the treatment modality of the patient.[24]

In this study, complexity Grade 1 was the most prevalent where prostheses with bounded saddles replacing posterior teeth, mucosa-borne prostheses, and prostheses replacing anterior teeth where there are suitable sound or restored teeth to provide anterior guidance were provided. This was not surprising because most of the prostheses were of Kennedy class III and IV where some anterior teeth/teeth were replaced, and the remaining teeth were able to provide the required support. This includes cases of single or multiple missing teeth where the options available are interim removable partial denture, cast partial denture, fixed partial dentures, and implant-retained prosthesis.[23] This contrasts with a previous study that was reported among 327 patients treated at East Hampshire with either removable or fixed dental prosthesis treatment; the most prevalent complexity grade was grade 2, however, the index of treatment need was used to provide a quick and easy assessment of treatment complexity for patients needing special treatment.[25]

Oro-facial defects are disconcerting to patients and may depressingly affect their physical and psychological health; this may possibly lead to serious psychiatric and social problems.[2] Prosthodontic care success depends on being able to meet the many patient-centered, oral health related quality of life-related goals fully recognized by prosthodontists.[26] These defects can be found either in the maxilla or mandible. They can be rehabilitated with the use of maxillofacial prosthesis to an acceptable function and aesthetics.[27] Effective interdisciplinary cooperation between surgeons, dentists, and technicians is needed for a long-lasting functional and aesthetic rehabilitation.[28] The presence of orofacial defects was observed in less than one tenth of the participants, and this may have caused a surge in the complexity of prosthetic treatment in these categories of patients. A situation where simple restoration may not give the required benefit but encompasses more complicated and sophisticated methods of rehabilitation where maxillofacial prostheses with antecedent challenges in retention, stability, and support are envisaged and proffered solution needed to give the required morale and boost to the patients. It could also involve the expertise of a psychologist who is able to help the patient understand and accept postoperative changes and limits of the treatment and position them toward future positive perspectives.[28]

An observation in this study showed most participants who received removable partial dentures were graded complexity 1, while those who received obturators and mandibular prostheses were graded complexity 3. This may be related to the assertion proffered above, where patients treatment with removable partial denture are straightforward and not difficult to rehabilitate when compared to the maxillofacial prostheses where in addition to loss of teeth, there are also loss of some vital oral structures (skin, bone, muscle, cartilage, and multiple layers of mucosa), hence, the complexity in treatment rehabilitation is quite challenging.[29]

Participants whose treatment needed rehabilitation with either anterior (94.2%) or posterior (47.6%) teeth were recorded as complexity grade 1, while those who required rehabilitation of both anterior and posterior teeth (38.1%) were observed to belong to complexity grade 3. This may be because the anterior and posterior teeth replaced were those for participants who had treatment with removable partial dentures, which constitute a much easier and less challenging means of rehabilitation, while some of those who were rehabilitated with anterior and posterior teeth were participants who had maxillofacial prostheses rehabilitation, a more challenging and exacting treatment procedure.

Those with Kennedy's class III and IV saddles rehabilitated recorded complexity grade 1 while Kennedy's class II saddles recorded complexity grade 3. The Kennedy class II saddle is distal extension saddle with a composite of tooth and mucosa support and have been associated with negative outcome when compared with class III and IV which are tooth-bounded saddles.[30] This is because of the variable tissue support potential in tooth-mucosa support that tends to add complexity to the design consideration, which is opposed to tooth-supported prosthesis where potential movement is less because resistance to functional loading is provided by the teeth.[17]


The most common grade of complexity encountered was Grade I. The pattern of complexity of treatment using removable dental prostheses was dependent on the type of prosthesis, teeth replaced, support, and saddle.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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