Biomechanics in Removable Partial Dentures: A Literature Review of FEA-Based Studies

Table 4

Studies reporting the biomechanical stress and displacement in implant-assisted removable partial denture with different designs.

Authors	Type of prosthesis	The examined independent variable				The reported dependent variable			Outcome
		Length	Width	Location	Inclination	Attachment	Stress	Deflection
Tribst et al. 2020 [55]	Four 3D models of conventional and ISRPD class II mod 2 with 3 different designs	—	—	(i) M1 at the 1^st molar; (ii) M2 at the 2^nd molar; (iii) M3 2 implants at the 1^st and 2^nd molars					(i) The highest stress concentration in the implant has been reported in the implants of M2 followed by M3; (ii) The implant in the 1^st molar region received less stress as in M1 and M3
Messias et al. 2019 [76]	Two 3D models of mandibular class I IARPD in 2 different locations	—	—	(i) M1 implants located at the premolar area; (ii) M2 at the premolar area	—	—	√	—	(i) The implant located in the premolar area exhibited the highest displacement in the posterior region, while the opposite happened when the implant was located in the molar area; (ii) The stress was more concentrated in the part of the major connector next to abutment teeth; (iii) More stress on the posterior part of the saddle was shown when the implant was located in the premolar area
Ortiz-Puigpelat et al. 2019 [77]	Two 3D models of mandibular class I IARPD in 2 different locations	—	—	Three different locations; (i) M1 at the 2^nd molar; (ii) M2 at the 1^st molar; (iii) M3 at the 2^nd premolar	—	—	√	—	When the implant was located in the 1st molar area, less displacement and minimum stress at the implant and the metal framework were reported
Andrei et al. 2015 [43]	One model for conventional and IARPD for Co-Cr mandibular class I	—	—	2 implants were placed bilaterally in the 2^nd molar area	—	—	√	√	(i) In the conventional RPD, the maximum stress was reported at the anterior (premolar) and posterior (2^nd molar) areas; (ii) There was a reduction in the maximum stress at the same area in IARPD compared with the conventional RPD; (iii) The lateral displacement was high at the distal edge of both prostheses but with a higher value in the conventional RPD than in IARPD
Memari et al. 2014 [17]	Three 3D models, one for class II IARPD in 3 different locations	—	—	(i) M1 at the 2^nd molar area; (ii) M2 at the 1^st molar area; (iii) M3 at the 2^nd premolar area	—	—	√	—	As the implant was placed more anteriorly, more stress was concentrated in the terminal abutment, reaching its maximum value when the implant was located next to the terminal abutment
Cunha et al. 2008 [80]	Five models: (i) Natural; (ii) Conventional; (iii) IARPD (3 models) Co-Cr mandibular class II	—	—	The implant location: (i) Distal (2nd molar); (ii) Middle (1st molar); (iii) Mesial (1st premolar)	—	—	√	√	(i) In all IARPD designs, there was a clear diminish in the displacement when compared with the conventional RPD; (ii) In IARPD, the lowest displacement has been exhibited in an implant located in the middle of the residual ridge and then the distal area of the ridge, while the mesial location of the implant showed the lowest stress in the terminal abutment; (iii) The mesially placed implant showed the highest stress value in the internal thread of the implant followed by the middle and then the distal area, which showed the least stress
El-Okel and Elnady 2013 [79]	Six 2D models; (i) Natural; (ii) Conventional; (iii) IARPD (4 models) Co-Cr mandibular class II	10 mm	3 & 3.5 mm	One implant in the 6^th and one implant in the 7^th molar region	—	—	√	—	(i) The stress on the terminal abutment was the least with an implant of and then in the 1st molar area, compared with implants of and , at the 2nd molar area; (ii) The highest stress has been recorded in the implant of and located in the 2^nd molar area, while the lowest stress has been recorded in the implant of and located in the 1st molar area
Fayaz 2015 [81]	Six 3D models of IARPD with two lengths and 3 different inclinations	(i) M1-3 (7 mm); M4-6 (10 mm)	4 mm	1^st molar area	(i) M1-3 at 0°, 10°,and 15°; M4-6 at 0°, 10°, and 15°, respectively	—	√	—	(i) Increasing the inclination of the implant has shown increase in the stress in the implant to reach the maximum in M6, while the stress in the terminal abutment decreased to the minimum; (ii) As the length of the implant increased, the stress on the abutment decreased
de Freitas Santos et al. 2011 [82]	Six 3D models of natural, conventional, and IARPD mandibular class II with 4 different angles	—	—	2^nd molar region	4 models with different inclinations were used: (0°, 5°, 15°, and 30°) in a mesial direction	—	√	√	(i) Adding an implant to assist RPD led to a significant reduction in the displacement of the prostheses; (ii) The stress around the apex of the terminal abutment in all models with implants has shown better distribution in 0° and 5° compared to 15° and 30°, which showed the highest stress

M: model; IARPD: implant-assisted removable partial denture.