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Fulltext Understanding the dental need and care during pregnancy: a review

Ngeow WC, Chai WL

Med J Malaysia, 1999 Mar;54(1):146-50.
PMID: 10972020

This paper reviews the oral and dental lesions that are seen during pregnancy. Trimester approach should be adopted in the management of the pregnant patients. A good dental preventive programme is essential. The significance of prescribing fluoride supplements and the use of dental radiography during pregnancy is also briefly reviewed.
Ultrastructural analysis of implant-soft tissue interface on a three dimensional tissue-engineered oral mucosal model

Chai WL, Brook IM, Emanuelsson L, Palmquist A, van Noort R, Moharamzadeh K

J Biomed Mater Res A, 2012 Feb;100(2):269-77.
PMID: 22045611 DOI: 10.1002/jbm.a.33245

A three dimensional tissue-engineered human oral mucosal model (3D OMM) used in the investigation of implant-soft tissue interface was recently reported. The aim of this study was to examine the ultrastructural features of soft tissue attachment to various titanium (Ti) implant surfaces based on the 3D OMM. Two techniques, that is, focus ion beam (FIB) and electropolishing techniques were used to prepare specimens for transmission electron microscopic (TEM) analysis of the interface. The 3D OM consisting of both epithelial and connective tissue layers was constructed by co-culturing human oral keratinocytes and fibroblasts onto an acellular dermis scaffold. Four types of Ti surface topographies were tested: polished, machined (turned), sandblasted, and TiUnite. The specimens were then processed for TEM examination using FIB (Ti remained) and electropolishing (Ti removed) techniques. The FIB sections showed some artifact and lack of details of ultrastructural features. In contrast, the ultrathin sections prepared from the electropolishing technique showed a residual Ti oxide layer, which preserved the details for intact ultrastructural interface analysis. There was evidence of hemidesmosome-like structures at the interface on the four types of Ti surfaces, which suggests that the tissue-engineered oral mucosa formed epithelial attachments on the Ti surfaces.
Fulltext Tumoral calcinosis misdiagnosed

Chai WL, Phang YH, Chong HC

International e-Journal of Science, Medicine & Education, 2018;12(1):18-20.
MyJurnal

Tumoral calcinosis is an uncommon condition which has been described to exist in primary and secondary forms. A lack of awareness of this entity can lead to unnecessary procedures and incorrect management. We report a case of a patient on peritoneal dialysis who presented with multiple painful joint swellings to the orthopaedic department. An initial diagnosis of septic arthritis was made, then revised to chronic tophaceous gout and referred to the rheumatology unit.
Transient loss of power of accommodation in 1 eye following inferior alveolar nerve block: report of 2 cases

Ngeow WC, Shim CK, Chai WL

J Can Dent Assoc, 2006 Dec;72(10):927-31.
PMID: 17187708

Unintended intravascular injection from inferior alveolar nerve blocks can result in frustrating distant complications affecting such structures as the middle ear and eyes. Possible complications affecting the eyes include blurring of vision, diplopia, mydriasis, palpebral ptosis and amaurosis (temporary or permanent). In this article, we present a complication that has been reported only rarely. Two patients developed transient loss of power of accommodation of the eye resulting in blurred vision after routine inferior alveolar nerve blocks on the ipsilateral side. Clear vision returned within 10-15 minutes after completion of the blocks. The possible explanation for this phenomenon is accidental injection into the neurovascular bundle of local anesthetic agents, which were carried via the blood to the orbital region. This resulted in paralysis of a branch of cranial nerve III, the short ciliary nerves that innervate the ciliary muscle, which controls accommodation.
Transcultural oral health care and the Chinese

Chai WL

Dent Update, 2000 Dec;27(10):515.
PMID: 11218617
The clinical significance of the retromolar canal and foramen in dentistry

Ngeow WC, Chai WL

Clin Anat, 2021 May;34(4):512-521.
PMID: 32020669 DOI: 10.1002/ca.23577

The mandibular canal is nowadays acknowledged as a major trunk with multiple smaller branches running roughly parallel to it. Most of these accessory canals contain branches of the inferior alveolar neurovascular bundle that supplies the dentition, jawbone, and soft tissue around the gingiva and lower lip. This article reviews the prevalence, classification and morphometric measurements of the retromolar canal and its aperture. A retromolar canal is a bifid variation of the mandibular canal that divides from above this main canal, and travels anterosuperiorly within the bone to exit via a single foramen or multiple foramina into the retromolar fossa. This foramen, termed the retromolar foramen, allows accessory branches of the inferior alveolar neurovascular bundles to supply tissues at the retromolar trigone. Clinically, it is of the utmost importance to determine the exact location of the mandibular canal and to identify its retromolar accessory branches when surgery in the posterior mandible is to be performed.
The clinical anatomy of accessory mandibular canal in dentistry

Ngeow WC, Chai WL

Clin Anat, 2020 Nov;33(8):1214-1227.
PMID: 31943382 DOI: 10.1002/ca.23567

The mandibular canal is a conduit that allows the inferior alveolar neurovascular bundle to transverse the mandible to supply the dentition, jawbone and soft tissue around the gingiva and the lower lip. It is not a single canal but an anatomical structure with multiple branches and variations. The branches are termed accessory, bifid or trifid canals depending on their number and configuration. A bifid mandibular canal is an anatomical variation reported more commonly than the trifid variant. Because of these variations, it is of the utmost importance to determine the exact location of the mandibular canal and to identify any branches arising from it prior to performing surgery in the mandible. This article reviews the prevalence, classification and morphometric measurements of these accessory mandibular canals, emphasizing their clinical significance.
Fulltext The biological seal of the implant-soft tissue interface evaluated in a tissue-engineered oral mucosal model

Chai WL, Brook IM, Palmquist A, van Noort R, Moharamzadeh K

J R Soc Interface, 2012 Dec 7;9(77):3528-38.
PMID: 22915635 DOI: 10.1098/rsif.2012.0507

For dental implants, it is vital that an initial soft tissue seal is achieved as this helps to stabilize and preserve the peri-implant tissues during the restorative stages following placement. The study of the implant-soft tissue interface is usually undertaken in animal models. We have developed an in vitro three-dimensional tissue-engineered oral mucosal model (3D OMM), which lends itself to the study of the implant-soft tissue interface as it has been shown that cells from the three-dimensional OMM attach onto titanium (Ti) surfaces forming a biological seal (BS). This study compares the quality of the BS achieved using the three-dimensional OMM for four types of Ti surfaces: polished, machined, sandblasted and anodized (TiUnite). The BS was evaluated quantitatively by permeability and cell attachment tests. Tritiated water (HTO) was used as the tracing agent for the permeability test. At the end of the permeability test, the Ti discs were removed from the three-dimensional OMM and an Alamar Blue assay was used for the measurement of residual cells attached to the Ti discs. The penetration of the HTO through the BS for the four types of Ti surfaces was not significantly different, and there was no significant difference in the viability of residual cells that attached to the Ti surfaces. The BS of the tissue-engineered oral mucosa around the four types of Ti surface topographies was not significantly different.
The Management of Persistent Pain From a Branch of the Trifid Mandibular Canal due to Implant Impingement

Aljunid S, AlSiweedi S, Nambiar P, Chai WL, Ngeow WC

J Oral Implantol, 2016 Aug;42(4):349-52.
PMID: 27078072 DOI: 10.1563/aaid-joi-D-16-00011

The mandibular canal is a conduit that allows the inferior alveolar neurovascular bundle to transverse the mandible to supply the dentition, jawbone, and soft tissue around the lower lip. It is now acknowledged that the mandibular canal is not a single canal but an anatomical structure with multiple branches and variations. Iatrogenic injury to branches of the mandibular canal that carry a neurovascular bundle has been reported to cause injury to the main canal as severe as if the main canal itself is traumatized. These injuries include bleeding, neurosensory disturbance, or the formation of traumatic neuroma, and so far, they have involved cases with the bifid mandibular canal. This current report presents a case of neurosensory disturbance that resulted from the impingement of a branch of a trifid mandibular canal during implant insertion. Its management included analgesics, reexamination, and reinserting a shorter implant.
Susceptibility of Enterococcus faecalis biofilm to antibiotics and calcium hydroxide

Chai WL, Hamimah H, Cheng SC, Sallam AA, Abdullah M

J Oral Sci, 2007 Jun;49(2):161-6.
PMID: 17634730

The purpose of this study was to investigate the antimicrobial efficacy of six groups of antibiotics and calcium hydroxide against Enterococcus faecalis biofilm in a membrane filter model. Two-day-old E. faecalis (ATCC 29212) biofilm was exposed to ampicillin, co-trimoxazole, erythr omycin, oxytetracycline, vancomycin, vancomycin followed by gentamicin, Ca(OH)(2), and phosphate-buffered saline (control). After 1 h of exposure, the antimicrobial activity was neutralized by washing each disc five times in PBS, and then the colony-forming units of the remaining viable bacteria on each disc were counted. The results revealed that only erythromycin, oxytetracycline and Ca(OH)2 showed 100% biofilm kill. An ANOVA with a Bonferroni post hoc test (P < 0.05) detected significant differences among the test agents, except in the ampicillin group versus the co-trimoxazole group. It is concluded that erythromycin, oxytetracycline and Ca(OH)2 are 100% effective in eliminating E. faecalis biofilm, whereas ampicillin, co-trimoxazole, vancomycin, and vancomycin followed by gentamicin are ineffective.
Fulltext Root and canal anatomy of mandibular first molars using micro-computed tomography: a systematic review

Al-Rammahi HM, Chai WL, Nabhan MS, Ahmed HMA

BMC Oral Health, 2023 May 29;23(1):339.
PMID: 37248469 DOI: 10.1186/s12903-023-03036-5

BACKGROUND: A thorough understanding of root and canal anatomy is crucial for successful root canal treatment outcomes. This systematic review aims to explore the published micro-CT studies investigated the anatomy of root and canal system in permanent mandibular first molars.
METHOD: An electronic search was performed on Web of science, PubMed, and Scopus. Micro-CT journal studies investigated the root and canal anatomy of permanent double-rooted mandibular first molars were included. Data on study characteristics, objectives of interest, specifications of the studies, and micro-CT specifications were extracted. Risk of bias assessment (ROB) of the included studies was performed using Anatomical Quality Assessment (AQUA) tool. The extracted data were presented in tables and figures to present and synthesise the results. A meta-analysis was performed for the studies related to the prevalence of Vertucci's canal configurations, middle mesial canal (MMC) configurations, and Fan's isthmus types.
RESULTS: Amongst 1358 identified studies, thirty met the inclusion criteria. In terms of the objectives, the selected studies showed high anatomical variability in mandibular first molars. Twenty-two (73%), 25 (83%), and 12 (40%) of the studies reported the population/ethnicity, micro-CT specifications, and ethical approval, respectively. 28 (93%) studies did not disclose the method of sample size estimation. In only 6 (20%) of the studies, the authors had calibrated the assessment approaches. Mostly, a potential ROB was reported in domain 1 (objective(s) and subject characteristics) and domain 3 (methodology characterization). Whilst, low risk was reported in domains 2 (study design), 4 (descriptive anatomy), and 5 (reporting of results). The overall ROB was reported to be ''moderate'' in the vast majority of the studies (27/30). Meta-analysis results showed high levels of heterogeneity among the studies related to MMCs (I2 = 86%) and Fan's isthmus (I2 = 87%). As for the root canal configuration, pooled prevalence showed that Vertucci type IV and type I were the most prevalent in mesial and distal root canals, respectively.
CONCLUSION: Based on moderate risk of bias level of evidence, micro-CT studies have shown wide range of qualitative and quantitative data presentations of the roots and canals in mandibular first molars. Protocol and registration. The protocol of this systematic review was prospectively registered in the Open Science Framework database ( https://osf.io ) on 2022-06-20 with the registration number 10.17605/OSF.IO/EZP7K.
Fulltext Review on prophylactic antibiotics for dental patients with prosthetic joints

Chai WL, Yong CK, Ngeow WC

Ann Dent, 2003;10(1):22-26.
MyJurnal

Most prosthetic joint infections originate from wound contamination or haematogenous seeding from distant sites of infection. Bacteraemia may follow dental treatment but there is little evidence of it related to prosthetic joint infection. Nevertheless, controversy continues with regards to the effect of dental treatment in patients with prosthetic joints. This article reviews current English literature regarding the use of antibiotic prophylaxis in the dental management of patients with prosthetic joints. Routine antibiotic prophylaxis is not recommended for every patient with prosthetic joints when receiving dental treatments. However, antibiotic prophylaxis may be prescribed for high-risk groups with predisposing factors to infection when undergoing dental treatment with high risk of bacteraemia.
Red man syndrome during administration of prophylactic antibiotic against infective endocarditis

Ngeow WC, Chai WL, Moody AB

J Ir Dent Assoc, 2000;46(3):92-4.
PMID: 11323942

Red man syndrome (RMS) is the occurrence flushing, pruritus, chest pain, muscle spasm or hypotension during vancomycin infusion. It usually happens as a result of rapid infusion of the drug but may also occur after slow administration. The frequency and severity of this phenomenon diminish with repeated administration of vancomycin. A case is presented whereby RMS occurred while prophylactic antibiotic against infective endocarditis was administered.
Recurrent gigantic pyogenic granuloma disturbing speech and mastication: a case report and literature review

Ong MA, Chai WL, Ngeow WC

Ann Acad Med Singap, 1998 Mar;27(2):258-61.
PMID: 9663321

A case of gigantic pyogenic granuloma with three recurrences in the lower anterior gingiva is presented. Surgical wide excision of the lesion is the treatment of choice. The tumour must be excised down to the periosteum and the irritants around it removed to avoid recurrence. A contributing factor to the gigantic lesion is hormonal changes during pregnancy. Long-term review for 18 months after the third surgery showed no evidence of recurrence at the surgical site.
Fulltext Quantification of the dental morphology of orangutans

Nambiar P, John J, Al-Amery SM, Purmal K, Chai WL, Ngeow WC, et al.

ScientificWorldJournal, 2013;2013:213757.
PMID: 24348143 DOI: 10.1155/2013/213757

Orangutans are believed to have close biological affinities to humans. Teeth being the hardest tissue provide useful information on primate evolution. Furthermore, knowledge of the pulp chamber and root canal morphology is important for dental treatment. A female Bornean orangutan and a Sumatran male orangutan skull were available for this study. Both of their dentitions, comprising 50 teeth, were scanned employing the cone-beam computed tomography for both metrical and nonmetrical analyses. Measurements included tooth and crown length, root length, enamel covered crown height, root canal length (posterior teeth), length of pulpal space (anterior teeth), and root canal width. Nonmetrical parameters included number of canals per root, number of foramina in each root, and root canal morphology according to Vertucci's classification. It was found that the enamel covered crown height was the longest in the upper central incisors although the canine was the longest amongst the anterior teeth. Both the upper premolars were three-rooted while the lower second premolar of the Sumatran orangutan was two-rooted, with two foramina. The mandibular lateral incisors of the Bornean orangutan were longer than the central incisors, a feature similar to humans. In addition, secondary dentine deposition was noticed, a feature consistent with aged humans.
Fulltext Profiling lysophosphatidic acid levels in plasma from head and neck cancer patients

Abdul Rahman M, Mohamad Haron DE, Hollows RJ, Abdul Ghani ZDF, Ali Mohd M, Chai WL, et al.

PeerJ, 2020;8:e9304.
PMID: 32547888 DOI: 10.7717/peerj.9304

Head and neck squamous cell carcinoma (HNSCC) represents a significant world health problem, with approximately 600,000 new cases being diagnosed annually. The prognosis for patients with HNSCC is poor and, therefore, the identification of biomarkers for screening, diagnosis and prognostication would be clinically beneficial. A limited number of studies have used lipidomics to profile lipid species in the plasma of cancer patients. However, the profile and levels of lysophosphatidic acid (LPA) species have not been examined in HNSCC. In this study, a targeted lipidomics approach using liquid chromatography triple quadrupole mass spectrometry (LCMS/MS) was used to analyse the concentration of LPA (16:0 LPA, 18:0 LPA, 18:1 LPA, 18:2 LPA and 20:4 LPA) in the plasma of patients with oral squamous cell carcinoma (OSCC) and nasopharyngeal carcinoma (NPC), together with healthy controls. The levels of three LPA species (18:1 LPA, 18:2 LPA and 20:4 LPA) were significantly lower in the plasma of OSCC patients, whilst the concentrations of all five LPA species tested were significantly lower in plasma from NPC patients. Furthermore, the order of abundance of LPA species in plasma was different between the control and cancer groups, with 16:0 LPA, 18:0 LPA levels being more abundant in OSCC and NPC patients. Medium to strong correlations were observed using all pairs of LPA species and a clear separation of the normal and tumour groups was observed using PCA analysis. In summary, the results of this study showed that the levels of several LPA species in the plasma of patients with OSCC and NPC were lower than those from healthy individuals. Understanding these variations may provide novel insights into the role of LPA in these cancers.
Numbness of the ear following inferior alveolar nerve block: the forgotten complication

Ngeow WC, Chai WL

Br Dent J, 2009 Jul 11;207(1):19-21.
PMID: 19590550 DOI: 10.1038/sj.bdj.2009.559

This article presents a distant complication in the auricle following the administration of a standard inferior alveolar nerve block. The patient experienced profound numbness of the auricle on the ipsilateral side of the injection that lasted for about an hour following unintended injection to the auriculotemporal nerve.
Modified silk fibroin scaffolds with collagen/decellularized pulp for bone tissue engineering in cleft palate: Morphological structures and biofunctionalities

Sangkert S, Meesane J, Kamonmattayakul S, Chai WL

Mater Sci Eng C Mater Biol Appl, 2016 Jan 1;58:1138-49.
PMID: 26478414 DOI: 10.1016/j.msec.2015.09.031

Cleft palate is a congenital malformation that generates a maxillofacial bone defect around the mouth area. The creation of performance scaffolds for bone tissue engineering in cleft palate is an issue that was proposed in this research. Because of its good biocompatibility, high stability, and non-toxicity, silk fibroin was selected as the scaffold of choice in this research. Silk fibroin scaffolds were prepared by freeze-drying before immerging in a solution of collagen, decellularized pulp, and collagen/decellularized pulp. Then, the immersed scaffolds were freeze-dried. Structural organization in solution was observed by Atomic Force Microscope (AFM). The molecular organization of the solutions and crystal structure of the scaffolds were characterized by Fourier transform infrared (FT-IR) and X-ray diffraction (XRD), respectively. The weight increase of the modified scaffolds and the pore size were determined. The morphology was observed by a scanning electron microscope (SEM). Mechanical properties were tested. Biofunctionalities were considered by seeding osteoblasts in silk fibroin scaffolds before analysis of the cell proliferation, viability, total protein assay, and histological analysis. The results demonstrated that dendrite structure of the fibrils occurred in those solutions. Molecular organization of the components in solution arranged themselves into an irregular structure. The fibrils were deposited in the pores of the modified silk fibroin scaffolds. The modified scaffolds showed a beta-sheet structure. The morphological structure affected the mechanical properties of the silk fibroin scaffolds with and without modification. Following assessment of the biofunctionalities, the modified silk fibroin scaffolds could induce cell proliferation, viability, and total protein particularly in modified silk fibroin with collagen/decellularized pulp. Furthermore, the histological analysis indicated that the cells could adhere in modified silk fibroin scaffolds. Finally, it can be deduced that modified silk fibroin scaffolds with collagen/decellularized pulp had the performance for bone tissue engineering and a promise for cleft palate treatment.
Modified porous scaffolds of silk fibroin with mimicked microenvironment based on decellularized pulp/fibronectin for designed performance biomaterials in maxillofacial bone defect

Sangkert S, Kamonmattayakul S, Chai WL, Meesane J

J Biomed Mater Res A, 2017 Jun;105(6):1624-1636.
PMID: 28000362 DOI: 10.1002/jbm.a.35983

Maxillofacial bone defect is a critical problem for many patients. In severe cases, the patients need an operation using a biomaterial replacement. Therefore, to design performance biomaterials is a challenge for materials scientists and maxillofacial surgeons. In this research, porous silk fibroin scaffolds with mimicked microenvironment based on decellularized pulp and fibronectin were created as for bone regeneration. Silk fibroin scaffolds were fabricated by freeze-drying before modification with three different components: decellularized pulp, fibronectin, and decellularized pulp/fibronectin. The morphologies of the modified scaffolds were observed by scanning electron microscopy. Existence of the modifying components in the scaffolds was proved by the increase in weights and from the pore size measurements of the scaffolds. The modified scaffolds were seeded with MG-63 osteoblasts and cultured. Testing of the biofunctionalities included cell viability, cell proliferation, calcium content, alkaline phosphatase activity (ALP), mineralization and histological analysis. The results demonstrated that the modifying components organized themselves into aggregations of a globular structure. They were arranged themselves into clusters of aggregations with a fibril structure in the porous walls of the scaffolds. The results showed that modified scaffolds with a mimicked microenvironment of decellularized pulp/fibronectin were suitable for cell viability since the cells could attach and spread into most of the pores of the scaffold. Furthermore, the scaffolds could induce calcium synthesis, mineralization, and ALP activity. The results indicated that modified silk fibroin scaffolds with a mimicked microenvironment of decellularized pulp/fibronectin hold promise for use in tissue engineering in maxillofacial bone defects. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1624-1636, 2017.
Managing complications of radiation therapy in head and neck cancer patients: Part VI. Management of opportunistic infections

Ngeow WC, Chai WL, Ramli R, Rahman RA

Singapore Dent J, 2006 Dec;28(1):19-21.
PMID: 17378338

Head and neck cancer is becoming a more recognizable pathology to the general population and dentists. The modes of treatment include surgery and/or radiation therapy. Where possible, pretreatment dental assessment shall be provided for these patients before they undergo radiation therapy. There are occasions, however, whereby head and neck cancer patients are not prepared optimally for radiation therapy. Because of this, they succumb to complicated oral adverse effects after radiation therapy. The last part of this series reviews the opportunistic infections that can occur to the perioral structure. Their management is briefly discussed.

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