All maxillary posterior teeth touch the occlusal plane EXCEPT:
1- First bicuspid.
2- Second bicuspid.
3- First molar.
4- Second molar.***
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Dental loss is a common condition in the world population and is associated with different conditions (Petersen, 2003). On the other hand, the restitution of these areas with dental implants increases significantly in recent years and the rehabilitation of the posterior maxilla sector is a constant challenge (Olate et al., 2012) since the presence of the maxillary sinus and the presence A highly spongy bone in this sector makes the implant installation and its stability complex (Shibayama et al., 1993).
Bone height variations have been observed when the teeth have been lost presenting both the vertical decrease of the alveolar process and also the pneumatization of the maxillary sinus (de Oliveira et al., 2013), which requires reconstructive processes prior to the installation of implants (Olate et al., 2012). Depending on this need, procedures such as maxillary sinus floor elevation, lateral bone grafts or variations are considered next to the implant installation (De Moraes et al., 2009; Kim et al., 2009).
The posterior maxilla sector between the first premolar and the second molar is the sector affected by this clinical situation so that knowing the impact of dental absence on bone height are relevant to identify the conditions that will occur at the time of the procedure surgical.
MATERIAL AND METHOD:
A sample was used for convenience of 70 subjects between 21 and 61 years treated during the years 2011 and 2012 in the Dental Teaching Clinic of the University of La Frontera; From here, 70 digital panoramic radiographs obtained in the Meca Plan unit of the Oral and Maxillofacial Imaging Unit of the same institution were obtained.
Each of the images was analyzed in the EasyDent V4 Simple Wiewer software and the bone height variables were studied for each of the 4 teeth between first premolar and second molar; when there were no teeth, the bone remnant equivalent to the height of the axial axis of each tooth was studied. The distance analysis points were the upper cortical point of the floor of the maxillary sinus and the inferior cortical point of the alveolar ridge located on the axial axis of the tooth or where the tooth should be (place obtained from 7 mm posterior from the central axis of the most anterior tooth present in the sector or from the canine in the case of absence of the teeth of the sector (Fig. 1) Each measurement was performed bilaterally by an observer on two different occasions with a difference of 1 week each measurement .
The data obtained were related to variables such as tooth absence, bone height and maxillary sinus amplitude level using the SPSS / PC + software version 20.0, SPSS, Chicago, IL. Anova tests of a factor for analysis of variance and chi-square tests of pearson were performed considering statistical significance when p <0 .05.="" p="">
RESULTS:
70 subjects with 140 hemimaxyles with an average age of 40.6 years ± 8.9 (range 21 to 61 years) were analyzed. Fifty patients were female (71.4%) and 20 subjects were male (28.6%). The patient's sex did not show significant influence on the maxillary bone height or the superior-inferior distance of the maxillary sinus (p> 0.05).
In the 140 units of analysis, 26 (18.6%) subjects maintained their second molar (2M), first molar (1M), second premolar (2PM) and first premolar (1PM), 37 (26.4%) subjects they had lost 1 tooth of the aforementioned, 48 subjects had lost 2 teeth (34.3%), 23 had 3 teeth absent in each sector (16.4%) and 6 (4.3%) hemimaxilas did not present the 4 teeth later. In terms of bone height, variable averages were observed where the dental presence in the 2M and 1M sectors was approximately 2 mm higher than when they were absent. In the case of 1PM and 2PM, no significant differences were observed in cases of presence or dental absence.
In this sense, the absence of 1PM was not significantly associated with the decrease in bone height and the loss of 2PM was not associated with the absence of bone height (p = 0.204). The presence of 1M was not significantly associated with the bone height of the 1M sector (p = 0.479) but was able to significantly influence the bone height of 2M (p = 0.000); on the other hand, the presence of 2M was also not statistically associated with the bone height of the sector (p = 0,150).
1- First bicuspid.
2- Second bicuspid.
3- First molar.
4- Second molar.***
-------------------------
Dental loss is a common condition in the world population and is associated with different conditions (Petersen, 2003). On the other hand, the restitution of these areas with dental implants increases significantly in recent years and the rehabilitation of the posterior maxilla sector is a constant challenge (Olate et al., 2012) since the presence of the maxillary sinus and the presence A highly spongy bone in this sector makes the implant installation and its stability complex (Shibayama et al., 1993).
Bone height variations have been observed when the teeth have been lost presenting both the vertical decrease of the alveolar process and also the pneumatization of the maxillary sinus (de Oliveira et al., 2013), which requires reconstructive processes prior to the installation of implants (Olate et al., 2012). Depending on this need, procedures such as maxillary sinus floor elevation, lateral bone grafts or variations are considered next to the implant installation (De Moraes et al., 2009; Kim et al., 2009).
The posterior maxilla sector between the first premolar and the second molar is the sector affected by this clinical situation so that knowing the impact of dental absence on bone height are relevant to identify the conditions that will occur at the time of the procedure surgical.
MATERIAL AND METHOD:
A sample was used for convenience of 70 subjects between 21 and 61 years treated during the years 2011 and 2012 in the Dental Teaching Clinic of the University of La Frontera; From here, 70 digital panoramic radiographs obtained in the Meca Plan unit of the Oral and Maxillofacial Imaging Unit of the same institution were obtained.
Each of the images was analyzed in the EasyDent V4 Simple Wiewer software and the bone height variables were studied for each of the 4 teeth between first premolar and second molar; when there were no teeth, the bone remnant equivalent to the height of the axial axis of each tooth was studied. The distance analysis points were the upper cortical point of the floor of the maxillary sinus and the inferior cortical point of the alveolar ridge located on the axial axis of the tooth or where the tooth should be (place obtained from 7 mm posterior from the central axis of the most anterior tooth present in the sector or from the canine in the case of absence of the teeth of the sector (Fig. 1) Each measurement was performed bilaterally by an observer on two different occasions with a difference of 1 week each measurement .
The data obtained were related to variables such as tooth absence, bone height and maxillary sinus amplitude level using the SPSS / PC + software version 20.0, SPSS, Chicago, IL. Anova tests of a factor for analysis of variance and chi-square tests of pearson were performed considering statistical significance when p <0 .05.="" p="">
RESULTS:
70 subjects with 140 hemimaxyles with an average age of 40.6 years ± 8.9 (range 21 to 61 years) were analyzed. Fifty patients were female (71.4%) and 20 subjects were male (28.6%). The patient's sex did not show significant influence on the maxillary bone height or the superior-inferior distance of the maxillary sinus (p> 0.05).
In the 140 units of analysis, 26 (18.6%) subjects maintained their second molar (2M), first molar (1M), second premolar (2PM) and first premolar (1PM), 37 (26.4%) subjects they had lost 1 tooth of the aforementioned, 48 subjects had lost 2 teeth (34.3%), 23 had 3 teeth absent in each sector (16.4%) and 6 (4.3%) hemimaxilas did not present the 4 teeth later. In terms of bone height, variable averages were observed where the dental presence in the 2M and 1M sectors was approximately 2 mm higher than when they were absent. In the case of 1PM and 2PM, no significant differences were observed in cases of presence or dental absence.
In this sense, the absence of 1PM was not significantly associated with the decrease in bone height and the loss of 2PM was not associated with the absence of bone height (p = 0.204). The presence of 1M was not significantly associated with the bone height of the 1M sector (p = 0.479) but was able to significantly influence the bone height of 2M (p = 0.000); on the other hand, the presence of 2M was also not statistically associated with the bone height of the sector (p = 0,150).
DISCUSSION:
The results of this investigation should be analyzed with caution. It is recognized that maxilla and jaw are metabolically active bones when they are in function and with teeth present (Olate et al., 2008), so that the absence or limitation of function can generate bone atrophy (Burkhardt et al., 1987) determining the loss or alteration of anatomical characteristics of the sector. Even so, the sinus membrane and its cellular content have been linked to bone neoformation, which allows rapid repair against exodontics or other types of aggressions or surgeries (Graziano et al., 2012).
It is feasible to think that dental absence determines a decrease in bone volume (Olate et al., 2008); However, only a few teeth, the 2 more posterior, showed significant variations in bone height which were not significantly associated with the level of the same. It is possible that mid-lateral measurements could present significant variations in bone loss (De Moraes et al.), Which was not evaluated in this investigation. On the other hand, the fact that the study population is a cross-sectional cohort without estimating the date of dental loss also limits the discussion of the results.
Even so, the data that shows the greatest bone loss later (1M and 2M) are interesting, probably because it is an area that requires more bone volume to keep the molars in position due to their larger size (De Moraes et al.) and because it is an area of greater spongy tissue (Burkhardt et al.) and greater trabecular space (Bianco et al., 2001), which could generate a greater volume of bone loss since the exodontics of 2M and / or 1M exist.
The 1PM area showed higher levels of bone height; the 2PM with less height, I also present a height level over 13 mm probably because in that sector the maxillary sinus is making its previous completion next to the ascent curve which would allow greater bone volume in the sector and also maintain a bone more corticalized, close to the canine area (De Moraes et al.).
The presence of the 4 maxilla posterior teeth allow bone heights of 10 and 11 mm in 1M and 2M teeth and more than 13 mm in 1PM and 2PM. The absence of the 4 molars generates a significant height decrease, close to half the height in the totally dentate zone and when there are losses of 2 or 3 teeth, varied heights are presented, generally with 25% of the height in the dentate area. On the other hand, the increase in the size of the maxillary sinus has also been linked to dental loss (Olate et al., 2012), which was verified in this investigation. Even so, no significant differences in maxillary distances (vertical or horizontal) were observed when compared to missing teeth.
Panoramic radiography is one of the most used imaging examinations in surgical planning so that it is the first to indicate bone pathologies or alterations; Even so, volumetric studies are important to study each surgical case (Neves et al., 2013). The installation of implants requires minimum heights of 10 mm in this sector (De Moraes et al.) And in light of these results some reconstructive or adaptive procedures are necessary in the installation of the implant in the posterior sector of 1M and 2M.
Finally, it can be concluded that bone absence in the dental loss sector is more important in the area of 1M and 2M when compared with 1PM and 2PM; The 1M and 2M sector can be linked to reconstructive processes more frequently than premolar teeth of the same hemimaxilla.
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Dentistry