It has been speculated that osseointegrated implants without periodontal receptors could be more susceptible to occlusal overloading and crestal bone loss because the load-sharing ability, adaptation to occlusal force, and mechanoperception are significantly reduced in dental implants.8
Thus, the present study was carried out (1) to measure the maximal occlusal forces (MOFs) in patients with implant-supported restorations, (2) to measure the marginal bone levels (MBLs) around these implant-supported restorations, and (3) to correlate the occlusal forces and MBLs around these implant-supported restorations.
The MOFs were measured by using a device (Digital IT strain gauge, H.E.M. Electronics, Miraj, India) that can bear a maximal occlusal load of 100 kg/mm2. The part of the strain gauge is a load cell that was placed into the oral cavity to record the forces. The forces were standardized by using a custom-made acrylic jig. A total of 3 values were recorded for MOFs with and without the use of the acrylic jig. This acrylic jig was fabricated to stabilize and reproduce the placement of the load cell in the oral cavity (Figure 1). The forces were recorded in the early morning, and patients were seated in alert feeding position to simulate the natural chewing position. These measurements of MOFs were carried out at the time of cementation of the final restoration, at 6 months, and at 12 months postrestoration.
When the MOFs were compared at the implant site and the contralateral site, with the use of jig and without the use of jig, at the time of cementation of the final restoration, at 6 months and at 12 months, a statistically significant difference (P < .05) was seen between them wherein higher forces were recorded with the use of jig (Table 1). However, comparison of MOFs at the implant site, with and without the use of jig and the MOFs at the contralateral site, with and without the use of jig, at different time intervals did not reveal any statistically significant differences (P > .05; Tables 2 through 4).
Comparison of maximal occlusal forces at the implant with the use of acrylic jig (IS1) and at the contralateral site with the use of acrylic jig (CS1) and maximal occlusal forces at the implant site without the use of acrylic jig (IS2) and at the contralateral site without the use of acrylic jig (CS2) at different time intervals*
The mean MOFs recorded at the implant site with the use of acrylic jig were 31.14 kg/mm2, and the mean MOFs recorded without the use of acrylic jig were 22.18 kg/mm2. The mean MOFs recorded at the contralateral healthy site with the use of acrylic jig were 25.71 kg/mm2, and the mean MOFs recorded without the use of acrylic jig were 17.53 kg/mm2. This is in contradiction to various studies reported in the literature.11 The occlusal forces depend on a number of factors that include gender, racial variations, diet, general build of the individual, musculature, dental arch size, vertical height of the load cell, and actual number of teeth involved in the bite effort.11
The inclusion criteria wherein the patients having only 1 single missing posterior tooth replaced with a dental implant and later restored along with split mouth design eliminated the errors related to the overload as well as being connected to natural teeth and also change in oral hygiene habits, change in oral intakes, and change in muscular activity, as done by Akca et al,8 Mericske-Stern et al,23 and Fontijn-Tekamp et al.24,25 It also provided a better understanding on the effect of normal occlusal forces on single implant-supported restorations.
The MOFs recorded give insight into the maximum amount of load that could have been put on the implants in normal function. The custom-made acrylic jig used in the current study standardized the placement of the load cell at all visits. It was observed that the amounts of forces recorded with the acrylic jig were considerably higher as compared to the forces recorded without the use of acrylic jig. This shows that the presence of any object between the occlusal surfaces of the opposing teeth leads to generation of higher masticatory forces by the muscles of mastication, which are eventually reflected in the readings recorded. The recording of occlusal forces without the use of acrylic jig was done to evaluate whether there was a difference with the use of acrylic jig, which was proven.
The study did not find any correlation between MOFs and MBLs. The results are in accordance with study by Akca et al8; however, these results are in contradiction to various other studies citied in the literature.7,19,35 The difference in the results could be attributed to the fact that occlusion was well stabilized in the present study in contrast to other studies citied above, where the effect of occlusal overload was evaluated. Therefore, it can be concluded that a well-stabilized occlusion holds the key to the success of an implant. The occlusal forces cannot be definitively said to be the only causative factor for bone loss around dental implants. 1e1e36bf2d