Satoshi Horita

Maxillofacial Fractures in Older Patients

PURPOSE The purpose of the present study was to analyze the trends and characteristic features of maxillofacial fractures in older patients. PATIENTS AND METHODS The data from 247 patients aged 65 years old or older, who were treated for maxillofacial fractures at the Department of Oral and Maxillofacial Surgery, Nara Medical University, from October 1981 to March 2010, were retrospectively analyzed. RESULTS Of the 247 patients, 127 were men and 120 were women; 50 patients had been treated in the first third of the period, 87 in the second, and 110 in the third. Injury had most frequently occurred because of falling on a level surface (n = 126), followed by a traffic accident (n = 84). Of the fractures, 140 were in the mandible, 90 in the midface, and 17 in both. In the mandible, the fracture lines were most frequently observed at the condyle, followed by the body, exclusively in edentulous patients. In the midface, the zygoma was mostly involved. The facial injury severity scale score ranged from 1 to 10 (average 1.81). Injury at other sites of the body was found in 45 patients. Observation was most frequently chosen (n = 127), primarily for those of older age, followed by open reduction and internal fixation in 46 and maxillomandibular fixation in 41 patients. The facial injury severity scale score was greatest in patients treated by open reduction and internal fixation, followed by those treated by maxillomandibular fixation. CONCLUSION Maxillofacial fractures in older patients have been increasing and showed the characteristic features of etiology, patterns, and treatment modalities.

Maxillofacial Fractures Resulting From Falls

PURPOSE The purpose of this study was to analyze maxillofacial fractures resulting from falls in terms of the demographics, the circumstance of injury, the site and severity of fracture, and the treatment. PATIENTS AND METHODS Data of 457 patients treated for fall-related maxillofacial fractures at the Department of Oral and Maxillofacial Surgery, Nara Medical University, Nara, Japan, from 1981 to 2007 were retrospectively analyzed. RESULTS Patients were 163 males and 116 females with an average age of 51.3 years who had fallen on a level surface (simple fall), and 110 males and 68 females with an average age of 31.9 years in falls from a greater height (fall from height), respectively. Fractures of the mandible were more frequently observed than those of the midface. In the mandible, fracture lines were exclusively observed at the condyle, especially in simple falls. In the midface, the zygoma was most frequently involved. Facial Injury Severity Scale ranged from 1 to 6, with an average of 1.78 in simple falls, and from 1 to 9, with an average of 2.04 in falls from height, respectively. These were dependent on the causes and height of the fall. Fractures at the other sites of the body were found in 14 patients (5.0%) with simple falls and 38 (21.3%) with falls from height. Maxillomandibular fixation was most frequently chosen for mandibular fractures and observation for midface fractures. Open reduction and fixation was more frequently chosen in patients with falls from height than those with simple falls and in patients with a higher Facial Injury Severity Scale score. CONCLUSIONS Maxillofacial fractures resulting from falls showed characteristic features in the demographics, the circumstance of injury, and the site and severity of fracture. Treatment was chosen according to these features.

Maxillofacial fractures due to work-related accidents

One hundred and three patients with maxillofacial fractures due to work-related accidents were analysed. Ninety-nine patients (96.1%) were male and 4 (3.9%) were female. The average age was 46.8 years (range 18-75 years). The injuries were most commonly sustained during construction (42 patients, 40.8%) followed by agriculture and forestry (31 patients, 30.1%) and manufacturing (15 patients, 14.6%). Being struck by an object was the main cause of injury (43 patients, 41.7%) followed by fall from one level to another (31 patients, 30.1%). Fifty-four patients (52.4%) had fractures in the mandible, 41 (39.8%) in the midface, and 8 (7.8%) in both the mandible and the midface. The most common sites for fractures were the condyle and symphysis in the mandible and zygoma in the midface. The facial injury severity scale ranged from 1 to 6 with an average of 1.99±1.18. There was no difference in the nature of the work being undertaken or the cause of the injury. Fractures in other sites were observed in 22 patients (21.4%). Open reduction and fixation was the most frequent treatment for mandibular fractures (25 patients, 40.3%) followed by maxillomandibular fixation (19 patients, 30.6%). Observation was most commonly used for midface fractures (18 patients, 36.7%) followed by open reduction and fixation (15 patients, 30.6%) and transcutaneous reduction (8 patients, 16.3%).

Impalement Injuries of the Oral Cavity in Children

PURPOSE The purpose of this study was to analyze impalement injuries of the oral cavity in children. PATIENTS AND METHODS Data on 144 children with impalement injuries in the oral cavity at the Department of Oral and Maxillofacial Surgery, Nara Medical University were analyzed retrospectively. RESULTS The patients were 93 boys and 51 girls (age range, 7 months to 10 years). One hundred thirty-two patients (91.7%) were younger than 5 years. Injuries occurred frequently by falling onto an object held in the mouth in 77 patients (53.5%). The impaled objects were a toothbrush in 30 patients (20.8%), a cylindrical toy in 27 (18.8%), and chopsticks in 19 (13.2%). The soft palate was frequently involved in 64 patients (44.4%), followed by the hard palate in 26 (18.1%). Computed tomographic examination was performed in 16 patients (11.1%). Observation with or without medication was most frequently chosen in 98 patients (68.1%). Surgical intervention was performed in 46 patients (31.9%), 41 under local anesthesia and 5 under general anesthesia. Admission was required in 12 patients (8.3%). No complications, such as deep infection or neurologic sequelae, were observed. CONCLUSIONS Most impalement injuries in the oral cavity in children heal spontaneously or with minimal intervention. These children can be followed on an outpatient basis with instructions to their parents about possible complications, except for a few selected cases.

Maxillofacial fractures sustained in bicycle accidents.

PURPOSE The purpose of this study was to analyze maxillofacial fractures sustained in bicycle accidents by demographics, cause of injury, site and severity of fractures, injuries to other sites of the body, and treatment modalities. PATIENTS AND METHODS Data on 307 patients treated for maxillofacial fractures sustained in bicycle accidents in the Department of Oral and Maxillofacial Surgery, Nara Medical University from 1981 through 2009 were analyzed retrospectively. RESULTS The patients were 166 males and 141 females (average age, 30.9 years). Causes of injury were a fall on a level surface in 169 patients, an automobile accident in 56, fall from 1 level to another in 28, and a motorcycle accident in 24. One hundred seventy-five fractures were observed in the mandible, 117 in the midface, and 15 in the mandible and midface. In the mandible, fracture lines were exclusively observed at the condyle. In the midface, the zygoma was most frequently involved. The Facial Injury Severity Scale ranged from 1 to 7 (average, 1.88). Injuries at other sites of the body were found in 47 patients and were frequently found in automobile and motorcycle accidents. Maxillomandibular fixation was most frequently chosen in 81 patients, followed by observation in 76 and open reduction and internal fixation in 71. The Facial Injury Severity Scale was highest in patients treated by open reduction and internal fixation, followed by those treated by maxillomandibular fixation. CONCLUSIONS Maxillofacial fractures sustained in a bicycle accident frequently occurred by falling on a level surface and were not so serious in most cases; however, in accidents with motor vehicles, injuries to other sites of the body were observed at a higher rate.

Influence of bone parameters on peri-implant bone strain distribution in the posterior mandible

Objectives: The success rate of dental implants depends on the type of bone at the implant site. The purpose of the present study was to investigate the effects of the bone parameters at the implant-placement site on peri-implant bone strain distributions. Study Design: The morphologies and bone densities of seventy-five potential implant sites in the posterior mandible were measured using computed tomography (CT). Based on the CT data, we defined bone parameters (low and high in terms of cancellous-bone density and crestal-cortical bone density, and thin and thick in terms of crestal-cortical bone thickness), and we constructed finite-element models simulating the various bone types. A buccolingual oblique load of 200 N was applied to the top of the abutment. The von Mises equivalent (EQV) strains in the crestal-cortical bone and in the cancellous bone around the implant were calculated. Results: Cancellous-bone density greatly affected the maximum EQV strain regardless of the density and thickness of the crestal cortical-bone. The maximum EQV strains in the crestal cortical-bone and the cancellous bone in the low-density cancellous-bone models (of 150 Hounsfield units (HU) were 1.56 to 2.62-fold and 3.49 to 5.31-fold higher than those in the high-density cancellous-bone models (of 850 HU), respectively. The crestal cortical-bone density affected the maximum EQV strains in the crestal cortical-bone and in the cancellous bone in the low-density cancellous-bone models. The crestal cortical-bone thickness affected the maximum EQV strains in the cancellous bone and in the crestal cortical-bone in the low-density cancellous-bone models. Conclusions: Our results confirm the importance of bone types for the peri-implant bone strain distribution. Cancellous-bone density may be a critical factor for peri-implant bone strain. Key words:Dental implant, bone density, finite-element analysis.

Maxillofacial fractures in children.

Abstract Maxillofacial fractures in Japanese children were retrospectively analyzed. The subjects were 287 patients aged 15 years and younger seeking treatment for maxillofacial fractures in the Department of Oral and Maxillofacial Surgery, Nara Medical University. The patients were 186 males and 101 females. Injuries most frequently occurred as a result of traffic accidents in 125 patients, 92 of which were bicycle-related accidents. Injuries by falling from one level to another were found in 49, primarily in younger children. One hundred seventy-nine fractures occurred in the mandible, 100 in the midface, and 8 in both. In the mandible, fractures most frequently occurred in condyle followed by symphysis. In the midface, alveolus was mostly involved. The facial injury severity scale ranged from 1 to 9 with an average of 1.83 and was higher in traffic accidents. Injury to other sites of the body was found in 33 patients, 28 of which occurred in traffic accidents. Observation was most frequently chosen in 84 patients. Intramaxillary fixation was chosen in 79, primarily for alveolar fractures and in younger children. Maxillomandibular fixation was chosen in 62 for mandibular fractures in older children. Open reduction and internal fixation was performed in 40, primarily in older children. The facial injury severity scale was higher in patients treated by open reduction and internal fixation and maxillomandibular fixation. Maxillofacial fractures in Japanese children showed characteristic features primarily depending on their age in terms of etiology, patterns, and treatment modalities.

The effects of bone density and crestal cortical bone thickness on micromotion and peri-implant bone strain distribution in an immediately loaded implant: a nonlinear finite element analysis.

Purpose This study investigated the effects of bone density and crestal cortical bone thickness at the implant-placement site on micromotion (relative displacement between the implant and bone) and the peri-implant bone strain distribution under immediate-loading conditions. Methods A three-dimensional finite element model of the posterior mandible with an implant was constructed. Various bone parameters were simulated, including low or high cancellous bone density, low or high crestal cortical bone density, and crestal cortical bone thicknesses ranging from 0.5 to 2.5 mm. Delayed- and immediate-loading conditions were simulated. A buccolingual oblique load of 200 N was applied to the top of the abutment. Results The maximum extent of micromotion was approximately 100 μm in the low-density cancellous bone models, whereas it was under 30 μm in the high-density cancellous bone models. Crestal cortical bone thickness significantly affected the maximum micromotion in the low-density cancellous bone models. The minimum principal strain in the peri-implant cortical bone was affected by the density of the crestal cortical bone and cancellous bone to the same degree for both delayed and immediate loading. In the low-density cancellous bone models under immediate loading, the minimum principal strain in the peri-implant cortical bone decreased with an increase in crestal cortical bone thickness. Conclusions Cancellous bone density may be a critical factor for avoiding excessive micromotion in immediately loaded implants. Crestal cortical bone thickness significantly affected the maximum extent of micromotion and peri-implant bone strain in simulations of low-density cancellous bone under immediate loading.

Clinical Analysis of Midfacial Fractures

Purpose: To analyze the features of midfacial fractures. Methods: Data of 320 patients treated for midfacial fractures during the past 10 years were retrospectively analyzed. Results: Patients were 192 male and 128 female. Their age ranged from 1 to 96 years old with the average of 42.1. Injury most frequently occurred by traffic accidents in 168 patients, followed by falls in 78, assaults in 31 and sports in 25. Pattern of the fractures was classified into zygoma in 159 patients, alveolus in 60, multiple sites in 54, maxilla in 45 and nasal bone in 2. Facial injury severity scale ranged from 1 to 12 with the average of 1.52. Injuries to other sites of the body were found in 90 patients. Fractures of multiple sites showed higher facial injury severity scale and were associated with injuries to other sites of the body at a higher rate. Observation was most frequently chosen in 153 patients, followed by open reduction and internal fixation in 72, intramaxillary fixation in 43 and transcutaneous reduction in 26. Conclusions: Midfacial fractures showed a variety of features in terms of the site and severity and associated injuries. Understanding these features is important to manage these patients properly.

Fate of developing tooth buds located in relation to mandibular fractures in three infancy cases

The fate of developing tooth buds located in relation to mandibular fractures was investigated in three infancy cases. Three infants, 2 girls and a boy, aged from 1 year and 5-months old to 2 years and 6-months old, were treated for dislocated mandibular fracture in the symphyseal region by manual reduction and fixation with a thermoforming splint and circumferential wiring under general anesthesia. Fracture healing was uneventful in all cases. A few years later, no obvious deformity of the jaw or malocclusion was observed; however, malformation of the crown was found in one of the permanent teeth on the fracture line in the first case. In the second case, no abnormality was observed in one of the permanent teeth on the fracture line, but the effect on the other tooth could not be evaluated due to abnormality of the tooth probably not related to the injury. In the third case, root formation was arrested in one of the permanent teeth on the fracture line and the tooth was lost early after eruption. The development of tooth buds on the fracture line is not predictable and therefore, should be monitored by regular follow up.