Pullout strengths of orthodontic palatal mini-implants tested in vitro

Abstract

Background/purpose: New modified mini-implants are used in orthodontic practice to reinforce palatal anchorage. The aim of this study was to evaluate the anchorage strengths of palatal mini-implants in terms of their vertical and horizontal pullout strengths. Materials and methods: Thirty palatal mini-implants (2 mm in diameter) of three brands (Absoanchor, Bio-Ray, and Lomas) were manually driven into artificial bone (Sawbones) to a depth of 5 mm. Their vertical and horizontal pullout strengths were measured using a material testing machine. The KruskaleWallis test was used to assess differences among brands (P < 0.05). Results: The pullout strengths of all the brands were significantly greater than routine orthodontic forces. The vertical pullout strength of the Absoanchor mini-implants was the lowest among the tested brands, and the horizontal pullout strengths of the Lomas and Absoanchor mini-implants were significantly higher than that of the Bio-Ray mini-implant. There was no significant relationship between the insertion torque and pullout strength in the vertical or horizontal directions. Conclusion: The pullout strengths of mini-implants were significantly greater than normal orthodontic forces. Moreover, no significant correlation was found between the insertion torque and pullout strength.

Insertion torque and orthodontic mini-implants: A systematic review of the artificial bone literature

“…A total of 23 articles fulfilled the eligibility criteria (Table 1). 13,14,16,[39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] Five of these articles were either complete or partial copies of original articles, and another three articles were suspect of duplicate publication because they appeared almost identical (Table 1). To control publication bias, multiple publications were counted as one study, and references of duplicate articles were only listed in the tables and not in the text of this article.…”

“…Parameters assessed for an association with MIT Authors Kim et al 39 Shape, length, and thread depth of OMIs Kim et al 40,a and Kim et al 41,b Kim et al 42 Diameter and mono or dual threads of OMIs Song et al 13 Shape of OMIs and cortical bone thickness Song et al 43,a Lim et al 14 Shape, diameter, and length of OMIs and cortical bone thickness Lim et al 44,a Yun and Lim 45 Design of cutting flute of OMIs and cortical bone thickness Brinley et al 16 Fluting and width of pitch of OMIs Kim et al 41 Shape, length, and mono or dual threads of OMIs Kim et al 40,a and Kim et al 39,b Hung et al 46 Pilot hole size and cortical bone bone density Chen et al 47 Diameter of OMIs and cancellous bone thickness Hong et al 48 Shape and mono or dual threads of OMIs Cho et al 49 Motor or hand-drilled pilot holes and cortical bone thickness Kim et al 50 Character of the surface treatment of OMIs Barros et al 51 Diameter of OMIs Cho et al 52 Character of the surface treatment of OMIs Cho and Baek 53 Shape of OMIs and predrilling depth Shah et al 54 Diameter and length of OMIs and cortical bone thickness and density Wu et al 55 Shape of OMIs Wang et al 56,c and Chen et al 57,c Wu et al 58 Shape of OMIs OMI: orthodontic mini-implant. procedure-related associations were considered because they were rated as ''moderate'' or ''high'' quality and therefore fitted our inclusion criteria.…”

“…Two forms of reporting bias were presented in four articles. [55][56][57][58] These studies, which were coauthored by many of the same investigators, reported different MIT values for the same experimental setup. Although small variations in findings are possible when repeating experiments, differences were not discussed by these authors.…”

“…Furthermore, standard deviations or ranges of MIT values were not listed in three of these articles. [56][57][58] Reporting bias did not affect our interpretation of outcomes, because associations presented in all four studies were rejected because of confounding (Table 4).…”

Primary Stability of Temporary Screws after Dentary and Orthopedic Forces under Static and Dynamic Load Cycles

“…Therefore, if a 5 N load was transferred to screws, only 0.85-1.25 N resulted in a vertical orientation, while 4.5-4.8 N were transmitted, pulling the screw in a horizontal direction. Different works have considered the pull out strength when evaluating the stability of temporary screws [43][44][45][46]. This parameter is a complementary indicator of primary stability, apart from placement torque.…”