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Classification system on the selection of number of implants and superstructure design on the basis available vertical restorative space and interforaminal distance for implant supported mandibular overdenture

View Article: PubMed Central - PubMed

ABSTRACT

Purpose:: The rehabilitation of the edentulous mandible is a challenge due to various limiting factors, of which the available vertical restorative space (AVRS) has been well understood in the literature. However, other anatomic variations such as arch form, arch size, and also the interforaminal distance (IFD) (due to the presence of mandibular nerve) are influential in the selection of size and position of implants, and thereby the prosthetic design.

Materials and method:: In the present study, 30 edentulous patients from a group of 300 edentulous patients, representing all the three jaw relations (Class I, II, and III) were evaluated for designing a classification that could help in a comprehensive treatment plan for the edentulous mandible. Dental panoramic radiographs of each individual with a trial or final prosthesis were made. The horizontal IFD and AVRS values were calculated.

Results:: One-way analysis of variance followed by post-hoc test (multiple comparison) and Bonferroni method having P < 0.05 as significant value showed an overall mean of 38.9 mm for horizontal distance and 13.69 mm for the AVRS in 30 edentulous patients.

Conclusion:: The results showed that in the majority of cases (90%) there is insufficient space to place a bar attachment supported by five implants for mandibular overdentures. This suggests that a universal treatment plan cannot be followed due to varying anatomic factors. Hence, it becomes imperative to have a set of clinical guidelines based on the AVRS and IFD, for the selection of implant number and type of attachment. The article proposes a simple classification system based on the AVRS and IFD for establishing guidelines in the treatment planning of the edentulous mandible, to aid in selection of implant size, number, and position along with the associated prosthetic design.

No MeSH data available.


Available vertical restorative space aiding the selection of type of superstructure for implant supported mandibular overdenture
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Figure 2: Available vertical restorative space aiding the selection of type of superstructure for implant supported mandibular overdenture

Mentions: For designing mandibular overdentures, the anterior mandible can be divided into five positions (from left first premolar to right first premolar), namely A, B, C, D, and E.[2] Implants are placed in these positions depending upon the arch size, jaw relation, interforaminal distance (IFD), and the available vertical restorative space (AVRS). For the placement of five implants with a minimum diameter of 3.3 mm in the mandibular interforaminal region, the space requirement for five implants needs to be approximately 44.5–48.5 mm [Figure 1], i.e., a 2 mm safe space from mental foramina; further, sometimes if there is a loop of inferior alveolar nerve, then additional 2 mm is needed as a safety distance from the mental nerve (4 mm); if a bar clip is to be placed, an interimplant distance of 6 mm is required for the clip accommodation, similarly for a bar superstructure with clips, the vertical space requirement is at least 15 mm from the alveolar crest [Figure 2].


Classification system on the selection of number of implants and superstructure design on the basis available vertical restorative space and interforaminal distance for implant supported mandibular overdenture
Available vertical restorative space aiding the selection of type of superstructure for implant supported mandibular overdenture
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837775&req=5

Figure 2: Available vertical restorative space aiding the selection of type of superstructure for implant supported mandibular overdenture
Mentions: For designing mandibular overdentures, the anterior mandible can be divided into five positions (from left first premolar to right first premolar), namely A, B, C, D, and E.[2] Implants are placed in these positions depending upon the arch size, jaw relation, interforaminal distance (IFD), and the available vertical restorative space (AVRS). For the placement of five implants with a minimum diameter of 3.3 mm in the mandibular interforaminal region, the space requirement for five implants needs to be approximately 44.5–48.5 mm [Figure 1], i.e., a 2 mm safe space from mental foramina; further, sometimes if there is a loop of inferior alveolar nerve, then additional 2 mm is needed as a safety distance from the mental nerve (4 mm); if a bar clip is to be placed, an interimplant distance of 6 mm is required for the clip accommodation, similarly for a bar superstructure with clips, the vertical space requirement is at least 15 mm from the alveolar crest [Figure 2].

View Article: PubMed Central - PubMed

ABSTRACT

Purpose:: The rehabilitation of the edentulous mandible is a challenge due to various limiting factors, of which the available vertical restorative space (AVRS) has been well understood in the literature. However, other anatomic variations such as arch form, arch size, and also the interforaminal distance (IFD) (due to the presence of mandibular nerve) are influential in the selection of size and position of implants, and thereby the prosthetic design.

Materials and method:: In the present study, 30 edentulous patients from a group of 300 edentulous patients, representing all the three jaw relations (Class I, II, and III) were evaluated for designing a classification that could help in a comprehensive treatment plan for the edentulous mandible. Dental panoramic radiographs of each individual with a trial or final prosthesis were made. The horizontal IFD and AVRS values were calculated.

Results:: One-way analysis of variance followed by post-hoc test (multiple comparison) and Bonferroni method having P < 0.05 as significant value showed an overall mean of 38.9 mm for horizontal distance and 13.69 mm for the AVRS in 30 edentulous patients.

Conclusion:: The results showed that in the majority of cases (90%) there is insufficient space to place a bar attachment supported by five implants for mandibular overdentures. This suggests that a universal treatment plan cannot be followed due to varying anatomic factors. Hence, it becomes imperative to have a set of clinical guidelines based on the AVRS and IFD, for the selection of implant number and type of attachment. The article proposes a simple classification system based on the AVRS and IFD for establishing guidelines in the treatment planning of the edentulous mandible, to aid in selection of implant size, number, and position along with the associated prosthetic design.

No MeSH data available.