Hard Tissue Changes Research Articles

Influence on alveolar resorption of the buccal bony plate width in the edentulous ridge expansion (E.R.E.) – an experimental study in the dog

To compare the hard tissue changes at implants installed applying edentulous ridge expansion (E.R.E.) at sites with a buccal bony wall thickness of 1 or 2 mm. In six Labrador dogs, the first and second maxillary incisors were extracted, and the buccal alveolar bony plates and septa were removed. After 3 months of healing, partial-thickness flaps were dissected, and the E.R.E. was applied bilaterally. Hence, an expansion of the buccal bony crest was obtained in both sides of the maxilla with a displacement of either a 1- or a 2-mm-wide buccal bony plate at the test and control sites, respectively. After 3 months of healing, biopsies were obtained for histological analyses. A buccal vertical resorption of the alveolar crest of 2.3 ± 0.8 and 2.1 ± 1.1 mm, and a coronal level of osseointegration at the buccal aspect of 2.7 ± 0.5 and 2.9 ± 0.9 mm were found at the test (1 mm) and control (2 mm) sites, respectively. The differences did not reach statistical significance. The mean values of the mineralized bone-to-implant contact (MBIC%) ranged from 62% to 73% at the buccal and lingual sites. No statistically significant differences were found. Horizontal volume gains of 1.8 and 1.1 mm were observed at the test and control sites, respectively, and the difference being statistically significant. Implants installed using the E.R.E. technique yielded a high degree of osseointegration. It is suggested that the displacement of buccal bony plates of 1 mm thickness is preferable compared with that of wider dimensions.

Hard and soft tissue changes around implants installed in regular‐sized and reduced alveolar bony ridges. An experimental study in dogs

To study bony and soft tissue changes at implants installed in alveolar bony ridges of different widths. In 6 Labrador dogs, the mandibular premolars and first molars were extracted, and a buccal defect was created in the left side at the third and fourth premolars by removing the buccal bone and the inter-radicular and interdental septa. Three months after tooth extraction, full-thickness mucoperiosteal flaps were elevated, and implants were installed, two at the reduced (test) and two at the regular-sized ridges (control). Narrow or wide abutments were affixed to the implants. After 3 months, biopsies were harvested, and ground sections prepared for histological evaluation. A higher vertical buccal bony crest resorption was found at the test (1.5 ± 0.7 mm and 1.0 ± 0.7 mm) compared to the control implants (1.0 ± 0.5 mm and 0.7 ± 0.4 mm), for both wide and narrow abutment sites. A higher horizontal alveolar resorption was identified at the control compared to the test implants. The difference was significant for narrow abutment sites. The peri-implant mucosa was more coronally positioned at the narrow abutment, in the test sites, while for the control sites, the mucosal adaptation was more coronal at the wide abutment sites. These differences, however, did not reach statistical significance. Implants installed in regular-sized alveolar ridges had a higher horizontal, but a lower vertical buccal bony crest resorption compared to implants installed in reduced alveolar ridges. Narrow abutments in reduced ridges as well as wide abutments in regular-sized ridges yielded less soft tissue recession compared to their counterparts.

Systematic Analysis of Clinical Outcomes of Anterior Maxillary and Mandibular Subapical Osteotomy With Preoperative Modeling in the Treatment of Bimaxillary Protrusion

The purpose of this study was to determine the changes in teeth and hard tissues after preoperative modeling and bimaxillary anterior subapical osteotomy for the treatment of bimaxillary protrusion. Cephalometric analysis was used to evaluate the aesthetic effects and occlusal relationships obtained. The subjects included 19 women and 1 man (aged 19-41 years; average, 29 years) with bimaxillary protrusion who underwent anterior subapical osteotomy of both the maxilla and mandible, with simultaneous genioplasty, if required. Based on a preoperative computer-aided manufacturing/design-assisted and model surgical design and an occlusal guide plate, new occlusal relationships were established for the patients. In addition, the preoperative and postoperative cephalometric radiographs were systematically analyzed. In all patients, the surgical incisions underwent primary healing, with no infection or osteonecrosis. Significant differences were observed in the preoperative and postoperative values of all hard tissue and teeth parameters, except for SGn-FH degrees and Co-MP. The most obvious significant differences were seen in L1-OP°, Id-Pog-Go°, IIA°, U1E-Apog, L1E-Apog, U1E-NA, and L1-NA° (P < 0.001). Postoperative follow-up lasted for 12 to 36 months. All patients eventually achieved normal jaw relationships, tooth arch forms, and Spee curves. No evident irregularities of teeth arrangement or abnormal occlusal relationships were observed. All patients were satisfied with their postoperative facial appearance, except for 1 patient, who underwent repeat surgery because of relapse. With the use of a precise preoperative model surgical design, orthognathic surgery, a simple and time-saving technique, can be used to correct bimaxillary protrusion with satisfactory postoperative occlusal relationship and facial aesthetic appearance and minimal postoperative complications.

Upper lip shortening combined with Lefort 1 maxillary intrusion: a novel approach to correct the long face syndrome

Lip lengthening is a common characteristic of aging caused by the weakening of the fascial attachments and decrease of lip volume. We report a comprehensive combined plastic-orthognathic surgery of a long face syndrome uncharacteristically associated with a long upper lip in a 37-year-old Caucasian woman. The deformity comprised increased lower face height, vertical maxillary excess, and increased gingival display upon smiling. The long lip (30.7 mm; norm, 20.1 + 2 mm) constituted a limitation to the routine maxillary Lefort impaction because of the expected deficient display of maxillary teeth at rest and during smile. Lip shortening (5 mm) through a crescent flap was combined with maxillary impaction (6 mm), mandibular advancement (8 mm), and genioplasty (8 mm). Post-treatment results revealed normal relations between the upper lip and both the lower facial features and the dentition, at rest and during smile. Research should explore the predictability of the observed hard and soft tissue changes in similar dysmorphologies.

Soft-Tissue Profile Changes following Early Le Fort III Distraction in Growing Children with Syndromic Craniosynostosis

The purpose of this study was to characterize soft-tissue profile changes following Le Fort III (midface) distraction in growing patients with syndromic craniosynostosis. The cohort consisted of 20 syndromic patients who underwent Le Fort III osteotomy with midface advancement using a rigid external distraction device. The mean age at surgery was 5.7 years (range, 3 to 12.5 years). Lateral cephalograms were obtained preoperatively (time 1), after distraction device removal (time 2), and 1 year after distraction (time 3). Ten skeletal hard-tissue and 11 soft-tissue profile landmarks were identified and digitized at time points 1, 2, and 3. The x and y displacement of each landmark was studied to determine the ratios for soft- to hard-tissue change. The horizontal ratio of soft- to hard-tissue change for nasal dorsum to orbitale was 0.73:1 and the soft-tissue tip of nose to the anterior nasal spine was 0.86:1. The horizontal ratio of soft-tissue A point to hard-tissue A point was 0.88:1. The horizontal ratio of the upper lip position to the labial surface of maxillary incisor was 0.88:1. The ratio for nasal tip elevation to the anterior nasal spine advancement was 0.27:1. The result of this study supported the hypothesis that there exists a linear relationship between soft- and hard-tissue changes in the horizontal direction for the midface landmarks following Le Fort III distraction. However, there was a nonlinear relationship between soft- and hard-tissue changes in the vertical direction. Therapeutic, IV.

Three-Year Follow-Up of a Single Immediate Implant Placed in an Infected Area: A New Approach for Harvesting Autogenous Symphysis Graft

Three-Year Follow-Up of a Single Immediate Implant Placed in an Infected Area: A New Approach for Harvesting Autogenous Symphysis Graft

Photometric Evaluation of Soft Tissue Changes in CLP Patients: Le Fort I Advancement Osteotomy (ALO) Versus Anterior Maxillary Distraction (AMD).

This paper is a comparative photometric evaluation of soft tissue changes in patients with CLP associated with maxillary deficiency treated with conventional Le Fort I advancement osteotomy (ALO) and anterior maxillary distraction (AMD). Twenty patients with maxillary hypoplasia associated with cleft lip and palate who had undergone either LeFort I osteotomy or distraction osteogenesis with maxillary advancement were included in this study. Frontal and profile photographs were used to ascertain the changes post-surgically. Photographs were obtained before treatment and 1year after surgical correction in both groups. Vertical as well as horizontal changes in pronasale was well observed in both groups. A substantial increase in nasal parameters was noted in case of AMD group in comparison to ALO group. Though maxillary advancement was quite evident in AMD and ALO groups, a significant and consistent change was observed in AMD group. Significant vertical and horizontal changes were seen with respect to subnasale and labrale superius in AMD group. The hard and soft tissue changes produced by AMD by intra oral distractors were being evaluated so far. The results of the above studies have proved the excellence of AMD over conventional osteotomies. The present study goes hand in hand with the research outcomes till date.

Evaluation of Minimal Versus Conventional Presurgical Orthodontics in Skeletal Class III Patients Treated With Two-Jaw Surgery

The purpose of this study was to compare changes in hard and soft tissues and the treatment efficacy of 2-jaw surgery combined with nonextraction treatment for skeletal Class III malocclusion in patients who received minimal presurgical orthodontics (MPO) versus those who received conventional presurgical orthodontics (CPO). Thirty-two patients (16 in each group) with skeletal Class III malocclusion who underwent 2-jaw surgery were included in the study. Serial lateral cephalometric films were traced at 4 stages: before treatment (T0), before surgery (T1), 1 month after surgery (T2), and at debonding (T3). Cephalometric measurements and treatment duration were compared using independent t test and Mann-Whitney U test. After the presurgical treatment phase, the angle between the lower incisor axis and mandibular plane, overjet, and soft tissue pogonion to the vertical reference line showed larger changes (P < 0.01) in the CPO group, whereas the pogonion to the horizontal reference line showed larger changes (P < .05) in the MPO group. In the postsurgical phase (T2 to T3), there were no significant differences between the 2 groups. Total treatment duration was significantly shorter in the MPO group. There were no significant differences between the MPO and CPO groups in the hard and soft tissue cephalometric variables. The MPO group had a shorter total treatment time. It is therefore recommended that clinicians consider these results when selecting MPO as a treatment option for accurate diagnosis and treatment planning of Class III surgical patients.

Three-dimensional soft-tissue and hard-tissue changes in the treatment of bimaxillary protrusion

Facial convexity related to bimaxillary protrusion is prevalent in many populations. Underlyingskeletal protrusion combined with increased dentoalveolar protrusion contributes to facial muscle imbalance and lip incompetence, which is undesirable for many patients. In this study, we evaluated the relationship between soft-tissue and hard-tissue changes in an orthodontically treated Asian population. Twenty-four consecutive adult Asian patients (mean age, 24 years), diagnosed with severe bimaxillary dentoalveolar protrusion, were evaluated using pretreatment and posttreatment cone-beam computed tomography. The patients were treated with 4 first premolar extractions followed by anterior retraction with either skeletal or intraoral anchorage. Serial cone-beam computed tomography radiographs were registered on the entire cranial base and fossa. Soft-tissue and hard-tissue changes were determined through landmark displacement and color mapping. Upper lip retraction was concentrated between the nasolabial folds and commissures. Lower lip retraction was accompanied by significant redistribution of soft tissues at pogonion. Soft-tissue changes correlated well with regional facial muscle activity. Significant retractions (2-4 mm) of the soft tissues occurred beyond the midsagittal region. Use of skeletal anchorage resulted in 1.5 mm greater lower lip retraction than intraoral anchorage, with greater retraction of the maxillary and mandibular incisor root apices. Profound soft-tissue changes accompanied retraction of the anterior dentition with both treatment modalities.

The effect of radiotherapy on dental hard tissue—a systematic review

Decay of teeth, erosion and disintegration of hard dental tissue are a clinically often seen side effect after radiotherapy for tumours in the head and neck region. To investigate if these side effects are due to structural changes in dental hard tissues, the current literature was searched. It can influence the quality of life gravely. A systematic PubMed (Medline) search was done and of the 374 hits, 11 articles were included. During the reading of these articles, 10 additional useful references to other articles were retrieved. An extra search was done on "A.M. Kielbassa", a key writer in many articles on this subject. Four extra articles were found. So in total, 25 articles were analysed in this systematic review. Tooth destruction occurs often and soon after irradiation. There is no difference between decay in irradiated and non-irradiated teeth. The locations and the progressiveness of the destruction are different in irradiated then in non-irradiated teeth. Several studies show changes in the structure and micro hardness of enamel, the dentinoenamel junction (DEJ) and dentin. The biomechanical properties are dramatically decreased. The odds of moderate/severe tooth damage increased with the irradiation dose. In conclusion the results of this systematic review show a great amount of changes and damages at all levels of the hard dental tissues, enamel, DEJ and dentin. These findings substantiate the idea that the formation of recurrent and atypical patterns of dental caries in irradiated teeth is, not only due to loss of saliva but a combination of both hyposalivation and the direct effects on hard dental tissue. The formation of atypical caries is furthermore increased due to poor oral hygiene, the increase of soft and carbohydrate-rich substance and changes of the bacterial micro flora and proteins. This article is written to understand more about the cause of destruction of teeth after radiotherapy. This way, a more adequate preventive and restorative treatment plan can be drawn up for an individual patient.

Soft and hard tissue changes in skeletal Class III patients treated with double-jaw orthognathic surgery—maxillary advancement and mandibular setback

The soft tissues of the facial profile may change after skeletal movement in orthognathic surgery. The aim of this study was to evaluate and compare the differences and correlation between hard and soft tissues after double-jaw surgery in skeletal Class III subjects. Radiographs from the following time points were assessed using Dolphin Imaging software: preoperative (T0), 2–4 months postoperative (T1), and 6–12 months postoperative (T2). Eleven hard and soft tissue points of the facial profile were evaluated. The Student's t-test was used to assess the significance of differences between the time intervals; Pearson's correlation coefficient was used to assess the significance of correlation existing between these points; significance was set at P<0.05. In the sample of 58 subjects, the correlation between hard and soft tissues in the mandible was greater than in the maxilla. Similarly, the correlations only between hard tissues and only between soft tissues presented a greater correlation in the mandible. The results are similar to those found in studies on single-jaw surgery for both the maxilla and the mandible. The influence of movements in hard tissues was restricted to the soft tissues of the same jaw, although there were exceptions.

Does Skeletal Surgery for Asymmetric Mandibular Prognathism Influence the Soft Tissue Contour and Thickness?

The purpose of the present study was to investigate whether asymmetric mandibular prognathism accompanies a fundamental difference in soft tissue thickness and whether asymmetric mandibular setback surgery would influence the contour and thickness of the soft tissue of the chin. The present retrospective study included skeletal class III patients with significant mandibular chin deviation greater than 6 mm at the pogonion, who had undergone cone-beam computed tomography before and 6 months after surgery during a 2-year period. The predictor variables were timing (pre- and postoperatively) and side (asymmetric vs contralateral). The outcome measures were the hard and soft tissue contours and soft tissue thickness of the chin at the infradentale, B-point, and pogonion level evaluated with reformatted computed tomography images. The study variables were statistically compared using regression model and correlation analysis. The present study consisted of 20 patients (10 males and 10 females; average age 20.2 years; range, 18 to 25). Preoperatively, the chin deviation side showed a more prominent hard and soft tissue outline but had a thinner soft tissue thickness, which camouflaged the hard tissue asymmetry. After surgery, the hard and soft tissue outline was greatly improved, and the soft tissue thickness had become nearly symmetric. Most of the soft tissue thickness changes correlated negatively with the hard tissue changes. Asymmetric mandibular prognathism accompanied the 3-dimensional soft tissue contour and thickness asymmetry. Because the soft tissue responds favorably after skeletal surgery, the correction of 3-dimensional asymmetry of bone should be emphasized in patients with asymmetric mandibular prognathism.

The accuracy of three-dimensional prediction planning for the surgical correction of facial deformities using Maxilim

The motivation for orthognathic surgery is to improve facial appearance and quality of life. This study aimed to validate a three-dimensional (3D) orthognathic planning programme (Maxilim) for predicting soft tissue changes following Le Fort I advancements. Cone beam computed tomography (CBCT) scans were taken before surgery (T1) and at 6–12 months after surgery (T2) for 13 patients. For each patient the 3D hard tissue changes between T1 and T2 were determined by CBCT superimposition on the cranial vault. Using Maxilim, each patient's skeletal movements were used to generate a 3D soft tissue prediction. The actual soft tissue mesh at T2 was compared to the predicted mesh. The face was divided into areas: nose, right and left nares, right and left paranasal regions, upper and lower lip, and chin. The absolute distance between meshes for each region was calculated. A one-sample t-test showed the distances between the meshes for all of the areas were within 3mm (P<0.05), except for the upper lip which was greater than 3mm (P=0.577). Using Maxilim, 3D soft tissue predictions for Le Fort I advancements were clinically satisfactory in the regions assessed, but associated with marked errors around the region of the upper lip.

Soft Tissue Changes in Cleft Lip and Palate Patients: Anterior Maxillary Distraction versus Conventional Le-Fort I Osteotomy

The purpose of the study was to compare the soft tissue changes after maxillary advancement in patients with maxillary deficiency associated with cleft lip and palate (CLP) by two approaches-anterior maxillary distraction (AMD) and advancement LeFort I osteotomy (ALO). Twenty patients with maxillary hypoplasia associated with cleft lip and palate who had undergone either LeFort I osteotomy or distraction osteogenesis with maxillary advancement were included in this study. Lateral cephalogram taken at various intervals of time were used to evaluate soft tissue and hard tissue changes over time. In both groups, vertical as well as horizontal changes in pronasale was well observed. A substantial increase in nasal parameters was noted in case of AMD group in comparison to ALO. Though maxillary advancement was evident in both the groups, a significant and consistent change was observed in AMD. Significant vertical and horizontal changes were seen with respect to subnasale and labrale superius in AMD group. Soft tissue as well as hard tissue relapse was greater in ALO group than AMD group. Significant soft tissue and hard tissue changes were clearly observed in both the groups, but the treatment results were more consistent in cases treated with AMD. Hence AMD could be considered as a better treatment of choice in cases of maxillary hypoplasia associated with cleft lip and palate.

Three-dimensional Planning in Orthognathic Surgery using Cone-beam Computed Tomography and Computer Software

The orthognathic surgery is the standard treatment for the correction of dentofacial deformities, in order to get a stable dental occlusion and facial harmony. The advancement of technology and the evolution of the concepts involved in the diagnosis and treatment plan in this area have been immeasurable, leading to the development of new methods, such as computer-aided jaw surgery system by a three-dimensional (3D) virtual surgical planning. The advent of the cone-beam computed tomography (CBCT) allows the acquisition of 3D images of the patient’s craniofacial complex and eliminates the ambiguity that can occur with two-dimensional (2D) images. Surgical simulation in 3D may benefit patients by providing a more accurate treatment plan and streamlined surgery, especially for patients with complex dentofacial deformities. The breakthrough of software tools for the diagnosis and treatment planning allows the construction of 3D surface models, dynamic cephalometry, semi-automatic mirroring in cases of asymmetry, interactive cutting of bone, bony segment repositioning, 3D splint manufacturing, bone reconstruction and visualization and prediction of the changes in hard and soft tissues of the face. The aim of this study was to report a case where the computed-assisted surgical planning predicts the possibility in achieving balance between aesthetic and function. Alterations in the virtual planning allow overcoming obstacles in actual surgery. Considering all possible details, the process provides greater predictability, practicality and precision in surgical planning.

A Rhinocerotid Skull Cooked-to-Death in a 9.2 Ma-Old Ignimbrite Flow of Turkey

BackgroundPreservation of fossil vertebrates in volcanic rocks is extremely rare. An articulated skull (cranium and mandible) of a rhinoceros was found in a 9.2±0.1 Ma-old ignimbrite of Cappadocia, Central Turkey. The unusual aspect of the preserved hard tissues of the skull (rough bone surface and brittle dentine) allows suspecting a peri-mortem exposure to a heating source.Methodology/Principal FindingsHere we describe and identify the skull as belonging to the large two-horned rhinocerotine Ceratotherium neumayri, well-known in the late Miocene of the Eastern Mediterranean Province. Gross structural features and microscopic changes of hard tissues (bones and teeth) are then monitored and compared to the results of forensic and archaeological studies and experiments focusing on heating effects, in order to reconstruct the hypothetical peri-mortem conditions. Macroscopic and microscopic structural changes on compact bones (canaliculi and lamellae vanished), as well as partial dentine/cementum disintegration, drastic enamel-dentine disjunctions or microscopic cracks affecting all hard dental tissues (enamel, cementum, and dentine) point to continued exposures to temperatures around 400–450°C. Comparison to other cases of preservation of fossil vertebrates within volcanic rocks points unambiguously to some similarity with the 79 AD Plinian eruption of the Vesuvius, in Italy.Conclusions/SignificanceA 9.2±0.1 Ma-old pyroclastic density current, sourced from the Çardak caldera, likely provoked the instant death of the Karacaşar rhino, before the body of the latter experienced severe dehydration (leading to the wide and sustainable opening of the mouth), was then dismembered within the pyroclastic flow of subaerial origin, the skull being separated from the remnant body and baked under a temperature approximating 400°C, then transported northward, rolled, and trapped in disarray into that pyroclastic flow forming the pinkish Kavak-4 ignimbrite ∼30 km North from the upper Miocene vent.

Bimaxillary surgery in Class III malocclusion: Soft and hard tissue changes

The aim of this study was to quantify anteroposterior facial soft tissue changes with respect to underlying skeletal movements after Le Fort I maxillary advancement and mandibular setback surgery with sagittal split osteotomy in Class III skeletal deformity by using lateral cephalograms taken before and after the operation.The material consisted of 31 patient (15 female, 16 male cases, mean age was 26.7 ± 2.5 years) with Class III skeletal deformity. All patients were treated by Le Fort I maxillary advancement and mandibular setback surgery with sagittal split osteotomy. Lateral cephalograms were taken before and 1.4 ± 0.3 years after surgery. Wilcoxon test was used to compare the pre- and post-surgical measurements. Pearson correlation test was used to compare the relationships between the skeletal, dental and facial soft tissue changes.In the maxilla, the APOINTAP (the anteroposterior position of A point) and ITIPAP (the anteroposterior position of upper incisor) showed significant protractions (−3.19 ± 3.63, and −3.19 ± 4.52, p < 0.01). In the mandible, the L1TIPAP (the anteroposterior position of lower incisor, −3.20 ± 5.83, p < 0.01), L1TIPSI (the superoinferior position of lower incisor, −2.43 ± 10.31, p < 0.05), BPOINTSP (the superoinferior position of B point, −2.28 ± 12.51, p < 0.05) and BPOINTAP (the anteroposterior position of B point, −3.19 ± 9.31, p < 0.01) showed significant retractions and upper positions after bimaxillary surgery. The insignificant decrease in soft tissue Pog–Vert distance was correlated the significant upper position of B point and lower incisor (r: 0.851, p < 0.001 and r: 0.842, p < 0.001).

Short‐term soft‐ and hard‐tissue changes following Class III treatment using a removable mandibular retractor: a randomized controlled trial

To evaluate the effects of a Class III functional appliance [the removable mandibular retractor (RMR)] in the early treatment of skeletal Class III deformities. SET-UP: Randomized controlled trial. Orthodontic Department, University of Al-Baath Dental School, Hamah, Syria. Sixty-seven skeletal Class III patients were recruited, distributed randomly into two groups: 1) treatment group (T) with the RMR: 33 patients (17 males and 16 females) with a mean age of 7.5 ± 1.33 years, 2) control group (C): 34 patients (15 males and 19 females) with a mean age of 7.3 ± 1.58 years. Lateral cephalograms were taken at the start of treatment (T1-T) or at the start of the observation period (T1-C) and after 14.5 ± 0.1 months (both groups). Soft- and hard-tissue changes in both groups were evaluated. The main significant findings in the treatment group were 1) anterior morphogenetic rotation of the mandible as a result of upward and forward condylar growth; 2) significant increase in maxillary length; 3) significant increase in maxillary dentoalveolar protrusion; 4) significant decrease in mandibular dentoalveolar protrusion; 5) significant protrusion of the upper lip; 6) significant retrusion of the lower lip; and 7) significant reduction in nasolabial angle. The RMR is an effective appliance in the treatment of skeletal Class III patients in the early mixed dentition in the short term.

Soft tissue response after Class III bimaxillary surgery

To analyze the impact of surgical change in anterior face height and skeletal relapse on the long-term soft tissue profile. Cephalometric radiographs of 81 patients taken before surgery and at five time points during a 3-year follow-up period were analyzed. All patients had Le Fort I and bilateral sagittal split osteotomies. The patients were divided into three subgroups according to the change in anterior face height during surgery. Calculations of soft to hard tissue ratios were based on the long-term soft tissue response relative to the surgical repositioning. The horizontal surgical repositioning varied considerably, depending on whether anterior face height was increased or decreased. For upper lip prominence, the pattern of long-term change was the same irrespective of change in face height. In all groups, upper lip thickness decreased in both the short term and the long term, particularly in patients with surgical increase in face height. Lower lip thickness increased in the short term but decreased during the follow-up period. There were significant associations between horizontal soft tissue and corresponding hard tissue changes, except for soft tissue A-point and upper lip, when face height was increased. The ratios were higher for mandibular variables than for maxillary variables, particularly for B-point and pogonion when anterior face height had decreased. A change in facial height influences the soft tissue response. The mandibular soft tissues closely follow skeletal relapse beyond 2 months postsurgery. The findings have clinical implications for the relative maxillary and mandibular repositioning when planning surgery.

Post-operative soft tissue changes in patients with mandibular prognathism after bimaxillary surgery

The objective of this study was to evaluate the three-dimensional soft tissue changes observed over time after bimaxillary surgery for mandibular prognathism using cone-beam computed tomography (CBCT) superimposed imaging. CBCT scans were obtained for 25 patients before bimaxillary surgery (T0), at 2 months after surgery (T1) and at 6 months after surgery (T2). Cephalometric variables from the reoriented volumetric images were measured and compared at T0, T1, and T2. The quantitative surface displacement in the middle and the lower third of the facial soft tissue using CMF tools was assessed by superimposing the T0 and T1 or T0 and T2 3D images. The soft tissue in middle third of face moved forward at T1 and significantly moved backward from T1 to T2 (Ch-Al, p < 0.001; Al, p < 0.05; Pn, p < 0.05). Most of the soft tissue changes from T1 to T2 were not correlated with the hard tissue changes (p > 0.05), while the cheeks were positively correlated with the soft tissue around them (Exo-Al, p < 0.01; Ch-Al, p < 0.01). Post-operative soft tissue changes occurred in the middle third of the face and are considered to be more complex than the changes in the lower third of face. Therefore, soft tissue assessment at least 6 months after surgery is desirable.