RSUSSH 2020

IN20-118 Prevalence and morphometric analysis of mandibular lingual concavity in alveolar ridge with adequate dimensions for standard implant placement

Presenter: Kavisara Sukumalchitkul
Mahidol university, Thailand

Abstract

          Objectives: Posterior mandibular lingual concavities are considered to be a predisposing factor for the lingual plate perforation during the implant installation. This rupture can create various complications ranging from hemorrhage to upper airway obstruction. The aim of this study is to determine the prevalence of ridge morphology and the dimension of the lingual concavity in the posterior mandibular region in Thai population and to find the relation between the dimension of undercut with other factors such as age and gender. Methodology: This study evaluated 102 cross sectional images of the mandibular second premolar and the first molar both in dentate and edentulous conditions. The alveolar ridges were classified into 3 types which were U-type, C-type and P-type. Then, the U-type ridges were further determined by measuring the dimensional parameters. Result and discussion: The distribution of U-type, P-type, C-type ridge in the posterior mandibular area was found to be 45.1%, 37.3%, 17.6% respectively on dentate ridge and 37.3%, 21.6%, 41.2% respectively on edentulous ridge. The relationships between the dimensional parameters and other factors, including age, gender, dental status and tooth type, were analyzed. However, there is the only negative correlation that existed between age and the depth of the lingual concavity (P<0.05). Conclusion: Lingual concavity is a common anatomy of the posterior mandible. However, even the ridge has adequate dimension, taking the CBCT image prior the implant surgery is recommended.

Keywords: Mandibular lingual concavity; Lingual undercut; Ridge morphology; Ridge prevalence; Concavity parameter

Citation format:

Sukumalchitkul, K., & Kretapirom, K.. (2020). Prevalence and morphometric analysis of mandibular lingual concavity in alveolar ridge with adequate dimensions for standard implant placement. Proceeding in RSU International Research Conference, May 1, 2020. Pathum Thani, Thailand.

QUESTIONS & ANSWERS

ผศ.ทพ.ปภาตพงศ์ ศิริคุรุรัตน์ (Chairperson)

1.What is the statistical analysis performed in this study?

2.What is the reason of being used 102 CBCT images for the population size? How did you enroll these subjects?

Sapatpon (Visitor)

1.How many times did you measure the dimension of mandibular concavity in each case? In addition of CT interpretation, if you cut the CT in different angles, the results would be presented in diffrent dimensions. 

2.In edentoulous case which you used the imaginary line, if the tooth which you use as a reference was malposed, the dimension of CT image could be distorted. How would you solve this problem? Did you use a radiographic stent as a reference in these edentulous cases?

Regards,

Sapatpon

Kavisara Sukumalchitkul (Presenter)

Dear Papardpong,

Thanks for your questions

1. We used chi-square test to evaluate the difference of prevalence among ridge morphology. To analyze the relation with concavity parameter (V,D,angle) , Pearson correlation was used with age and 2-sample T test was used with gender, tooth type and dental status 

2. The number of CBCT images used in this study was calculated from statistic formula which we used the percentage of undercut ridge type that can be found in previous studies as a reference, because this group of ridge types was the one that we most concerned. The subjects which passed the inclusion criteria were selected from the CBCT database at the Oral and Maxillofacial Radiology Clinic, Faculty of Dentistry, Mahidol university.

Kavisara Sukumalchitkul (Presenter)

Dear Sapatpon,

Thanks for your questions

1.  In the part of measuring the concavity parameters, we randomly chose 30 images and reexamined with 4-week intervals. The intraexaminer agreement was calculated with Pearson correlation test and the result showed the similar direction of the different 2 times of measurement with statistical significance. This could be described as the high level of reliability.

2. In our study, we did not use the surgical stent as a reference. To avoid the problems as you previously mentioned, we indicate clearly in the inclusion criteria that the adjacent teeth next to the selected edentulous ridge had to present and were in normal position ( the imaginary line connecting the cusp tip of canine, central groove of premolars and molars was generally smooth). Then we can measure in the middle area between those two adjacent teeth.

Regards,

Kavisara

 

Supranee Benjasupattananan, DDS (Chairperson)

1. Regarding to the vertical distance from crest to the deepest point of lingual concavity, if we plan to place dental implant length 10 mm, will the ridge morphology be affected our plan?

2. Why the prevalence of ridge morphology in dentate is different fromedentulous area ?

Kavisara Sukumalchitkul (Presenter)

Dear Supranee,

Thanks for your questions

1. From our study, in the undercut ridge type, the mean vertical distance from the top of the crest to the deepest point of the lingual concavity was around 15-16mm which exceeded the length of standard implant (10mm). The influence of the ridge morphology to the length of implant could be low, however; It possibly affect the treatment plan in some cases which the deep point of concavity extended along the height of the alveolar ridge.

2.It could be resulted from the different rate and process of ridge resorption between dentate and edentulous ridge.

Regards,

Kavisara