There are two anatomical structures in the human body that share the same name, which is the coronoid process. The first one is located in the mandible, which is the jaw bone, while the second one is located in the ulna, a long bone in the forearm. Both places have a triangular configuration. The coronoid process of the mandible is a slender and triangular prominence that is horizontally flattened and exhibits variations in both shape and size. The coronoid process exhibits three distinct morphological variations: rounded, triangular, and hook-shaped [1]. This process ascends vertically and modestly advances in the forward direction. The object possesses a convex upper border and a concave lower section. The temporalis muscle is attached to both its edges and its medial surface. The different shapes of the coronoid process of the mandible can be attributed to either functional or genetic factors and are closely related to how the temporalis muscle is attached. The many forms of the coronoid process serve as an indicator of evolution and are highly valuable in anthropological and forensic research. The coronoid process holds significant clinical importance for maxillofacial surgeons in the field of reconstructive procedures [2]. Autogenous bone grafts can be harvested from the ilium, rib, or calvarias; however, these locations have their own inherent morbidity. Therefore, we can acquire a regional bone transplant from the coronoid process of the mandible, which can be conveniently collected with minimal negative impact on the patient's health and reduced duration of both the surgical procedure and hospital stay. During this treatment, there is no scarring on the skin because the bone is taken from inside the mouth. A coronoid process graft can be utilised for different procedures such as mending a fractured mandible that hasn't healed properly, repairing the orbital floor, fixing flaws in the alveolar region, and also for augmenting the maxillary area [3]. The coronoid process can potentially serve as a donor location for sinus augmentation [4]. Consequently, we are examining the prevalence of various shapes of the coronoid process in the mandible among the population of Bihar and comparing it to the results of previous studies.

This study was a cross-sectional study conducted on 50 fully ossified adult human mandibles (100 sides). The mandibles were obtained from first-year MBBS students from the Department of Anatomy and Forensic Medicine, Nalanda Medical College, Patna, Bihar, and also from different medical colleges in the Bihar state of India. The age of the bones utilized in the investigation was not pre-established. The study only included mandibles that were fully ossified, dried, macerated, and carefully cleaned. These mandibles had to be complete in all aspects to ensure accurate observations. Any mandibles with deformities or pathology were not included in the study. The shapes of the coronoid process on both sides of the mandibles were studied and compared to identify any discrepancies between the two sides. Photographs were captured using a digital mobile camera. GraphPad Prism version 4.03 is a software utilized for conducting statistical analysis of data. Continuous variables are quantified using measures such as mean and standard deviation, whereas categorical variables are quantified using percentages

In the present study, we identified three different shapes of the coronoid process based on the descriptions by Isaac B. and Holla S. J. [5]: (A) Triangular, (B) Hook, and (C) Rounded. [Figures 1 and 2]

• The triangular-shaped coronoid process was observed in 63 (63%) cases. Of these, 56 (56%) mandibles had bilateral triangular processes, while seven (7%) had unilateral triangular processes (two on the right side and five on the left).
• The hook-shaped coronoid process was found in 24 (24%) cases. Of these, 19 (19%) mandibles had bilateral hook processes, while five (5%) had unilateral hook processes (two on the right side and three on the left).
• The round-shaped coronoid process was the least common, observed in only 13 (13%) cases. Of these, nine (9%) mandibles had bilateral round processes, while four (4%) had unilateral round processes (two on the right side and two on the left).

Overall, the triangular-shaped coronoid process was the most common in our study, while the round shape was the least common. Bilateral occurrences of all three shapes were more frequent than unilateral occurrences.

Table 1:  Prevalence of various shapes of the coronoid process and its percentage

 Figure 1: Distribution of different shapes of coronoid process

Figure 2: Showing different types of the coronoid process (A) Triangular-shaped coronoid process (B) Hook-shaped coronoid process, and (C) Round-shaped coronoid process

Various researchers from around the world have conducted several studies on different races and population groups about the coronoid process. We have compared their findings with our data and observations.

Table 3: Comparison of Incidences of different shapes of the coronoid process in various studies.

After comparing and assessing the findings of the current study with those acquired by previous researchers, significant distinctions as well as resemblances were identified. The most prevalent shape of the coronoid process is triangular, whereas a round shape is the least prevalent. This finding aligns with the studies conducted by Issac B et al [5], Khan TA et al [6], Prajapati VP et al [3], Nirmale et al [8], Desai VC et al [9], Sanmugam K. [11], and Kadam SD et al [12]. Hossain SMA [7] and Mouna S et al [10] reported that a hook-shaped coronoid process was the most frequently observed. The triangular-shaped coronoid process was recognized as the second most prevalent kind. In our study, we observed a triangular-shaped coronoid process in 63% of instances, which closely aligns with the findings of Khan TA et al [6], who found a triangular-shaped coronoid process in 67% of cases. In our study, we observed a round-shaped coronoid process in 13% of instances, which is the least common occurrence. This finding closely aligns with the results of Mouna S et al [10], who reported a round-shaped coronoid process in 12.5% of cases. We did not analyze the distribution of various coronoid process variations in the mandibles of males and females. According to Kadam SD et al [12], the triangular shape was more prevalent in both males and females. Among the 204 cases with the triangular coronoid process, there were 105 cases in men and 99 cases in females. The study revealed nearly the same occurrence of the hook type in both male and female mandibles, namely 34 cases in males and 32 cases in females out of a total of 66 cases with a hook form. In addition, the researchers assessed the intercoronoid distance in mandibles and determined that the results were not statistically significant for both male and female mandibles. The researchers discovered that the average intercoronoid distance was 9.3 cm in male mandibles and 9.2 cm in female mandibles. Anatomical differences in the form of the coronoid process can cause the vestibular space to become narrower due to the proximity of the medial portion of the coronoid process to the distal molar teeth. This can lead to impingement, which can create a limitation in the opening of the mouth and reduced movement of the lower jaw [11].  The coronoid process is a highly suitable site for obtaining grafts in the restoration of orbital floor abnormalities [13]. Clauser et al [14] documented the utilization of a temporalis myofascial flap, either as a standalone flap or in conjunction with cranial bone, in their study.  The arteries that provide blood to the coronoid process typically originate from vessels that also supply the muscles linked to these processes. Typically, it does not originate from the inferior alveolar artery, which mainly provides blood to the mandibular body and teeth. The coronoid process, along with the skin island, is frequently employed in many forms of reconstructive craniomaxillofacial surgery, such as temporomandibular joint ankylosis, tumors, injuries, abnormalities, and facial paralysis. No functional impairments are seen following the removal of the coronoid process.

Study limitations: The age and sex of the mandible bones were not examined because the information was not accessible. Additionally, as the results are unique to the North Indian population, more research across various ethnic groups and geographic regions is necessary to generalize the study's findings.

Understanding the different shapes of the coronoid process of the mandible is crucial for dental surgeons performing oral and maxillofacial surgeries. The coronoid process can be easily harvested as a donor bone and is well-suited for paranasal augmentation due to its size and morphology, which fit well into the paranasal region. Additionally, its availability, biocompatibility, and the reduced time required for harvesting make it highly advantageous. This knowledge also aids in determining the buccal vestibule during denture fabrication and is valuable in various anthropological studies and forensic dentistry.

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